Direct Seeding Southern Pines:

History and Status of a Technique 

Developed for Restoring Cutover Forests 

James P. Barnett

United States Department of Agriculture

Forest Service

Research & Development

Southern Research Station

General Technical Report SRS-187
Cover:  Harold J. Derr, research forester for the Southern Forest Experiment Station,

Pineville, LA, sowing longleaf pine seeds with a cyclone seeder in 1954. Derr was a

leader in the development of direct seeding technology.

Photo credits:  Unless otherwise noted, the photographs are from collections of the

U.S. Forest Service. Many of the photographs were taken by contract photographers,

Elmore Morgan and Tommy Kohara.

Product Disclaimer

The use of trade or firm names in this publication is for reader information and does not

imply endorsement by the U.S. Department of Agriculture of any product or service.

Pesticide Precautionary Statement

This publication reports research involving pesticides. It does not contain

recommendations for their use, nor does it imply that the uses discussed here have been

registered. All uses of pesticides must be registered by appropriate State and/or Federal

agencies before they can be recommended. CAUTION: Pesticides can be injurious

to humans, domestic animals, desirable plants, and fish or other wildlife—if they are

not handled or applied properly. Use all pesticides selectively and carefully. Follow

recommended practices for the disposal of surplus pesticides and pesticide containers.

Conversions

1 acre=0.40 hectare 1 fluid ounce=29.6 milliliters

1 foot=30.5 centimeters 1 pound=0.45 kilograms

1 inch=2.54 centimeters 1 tablespoon=14.8 milliliters

1 bushel=0.035 cubic meters 1 gallon=3.78 liters

January 2014

Southern Research Station

200 W.T. Weaver Blvd.

Ashevile, NC 28804

www.srs.fs.usda.gov

The Author:

James P. Barnett, retired Chief Silviculturist

and Emeritus Scientist, U.S. Department of

Agriculture Forest Service, Southern Research

Station, Pineville, LA 71360.
Direct Seeding Southern Pines: 

History and Status of a 

Technique Developed for 

Restoring Cutover Forests

James P. Barnett
ii

PREFACE

For centuries, foresters throughout the World have been intrigued by the idea of

establishing forest stands by sowing limited quantities of seeds at the right time on a

suitable seedbed. Following the harvest of southern pine forests during the late 19th and

early 20th centuries, the great need for reforestation in the South called for innovative

ideas. Millions of acres of cutover forests lay decimated with no residual source of seed

that could provide natural regeneration.

Pioneers in reforestation of southern pines conducted numerous trials of seeding, and

although there were occasional successes, failures greatly outnumbered them. These early

attempts did show, however, that the biggest obstacle to seeding was seed predation by

birds and rodents.

Research on direct seeding began in 1947 by scientists of the Southern Forest Experiment

Station located at Alexandria, LA. The objective of this research was to find a practical

method of protecting seeds from birds, since resident and migratory species are numerous

on these cutover areas when pine seeds were sown. Led by efforts of Harold J. Derr

and William F. Mann, Jr., a breakthrough was found in 1953 when anthraquinone and

an imported commercial repellent containing anthraquinone were found to be effective,

nontoxic bird repellents.

A formulation of the fungicide thiram was found to be equally effective in protecting

seeds from birds. By the end of l957, a seed coating was tested that included thiram

and endrin which repelled birds, rodents, and many insects. Pilot trials were undertaken

immediately by industrial landowners, mostly in Louisiana where the research was

conducted. The early operations were so successful that the technique soon was applied

around the region, and within 10 years almost 1 million acres were directly seeded with

southern pines.

The practice proved applicable in all parts of the South, and an intensive supporting

research program began to provide the additional quantities of seed needed to control the

many species of undesired, low-quality hardwoods that occupied many pine sites, and to

determine the extent that site preparation practices were needed for successful seeding.

Direct seeding was highly effective in restoring southern pines to millions of acres of

cutover forest land throughout the South. However, as much of the open forest land was

regenerated by planting and seeding efforts, the need for direct seeding declined. Use

of seeding is most appropriate on these large, open areas. Also, loss of the availability

of endrin, an effective rodent repellent, further limited the application of seeding. The

replacement rodent repellent, concentrated hot sauce or capsicum, is less effective than

was endrin.

Although direct seeding is inexpensive compared to planting of bareroot nursery stock,

it is frequently less successful and may require precommercial thinning of resulting

overstocked stands. It is now used primarily to regenerate large forested areas destroyed

by wildfire. It did, however, serve as a valuable application in response to the huge

reforestation problem resulting from the deforestation of the South’s pine lands during the

late 19th and early 20th centuries.

James P. Barnett
iii

PREFACE........................................................................................................................................................................... ii

THE NEED FOR DIRECT SEEDING TECHNOLOGY .............................................................................................. 1

EARLY SEEDING ATTEMPTS....................................................................................................................................... 2

INITIATION OF A SEEDING RESEARCH PROGRAM ............................................................................................. 2

DEVELOPMENT OF REPELLANTS............................................................................................................................. 3

Bird Repellents ............................................................................................................................................................ 4

Rodent Repellents........................................................................................................................................................ 4

Chemicals to Aid Coating Applications....................................................................................................................... 5

Seed Coating Techniques ............................................................................................................................................ 6

SEED QUALITY AND QUANTITY................................................................................................................................. 6

Procurement ................................................................................................................................................................. 6

Collection and Processing............................................................................................................................................ 7

Seed Storage and Testing ............................................................................................................................................. 9

Storing Repellent-Treated Seeds................................................................................................................................ 10

Stratification............................................................................................................................................................... 10

WHERE AND WHAT TO SEED.................................................................................................................................... 10

Where to Seed............................................................................................................................................................ 10

What Species to Seed................................................................................................................................................. 11

SITES AND SEEDBED PREPARATION .................................................................................................................... 11

Prescribed Fire ........................................................................................................................................................... 11

Disking....................................................................................................................................................................... 12

Amelioration .............................................................................................................................................................. 12

Control of Competing Vegetation .............................................................................................................................. 13

TIMING AND SOWING RATES.................................................................................................................................... 14

SEED DISTRIBUTION................................................................................................................................................... 14

Ground Methods ........................................................................................................................................................ 15

Aerial Methods........................................................................................................................................................... 15

Calibrating Seeding Equipment ................................................................................................................................ 16

APPRAISALS.................................................................................................................................................................. 17

Estimating Predator Activity...................................................................................................................................... 17

Identifying Causes of Seed and Seedling Losses....................................................................................................... 18

Seedling Inventories................................................................................................................................................... 18

STAND PROTECTION AND MANAGEMENT........................................................................................................... 19

Use of Prescribed Fire................................................................................................................................................ 19

Precommercial Thinning............................................................................................................................................ 20

CONTENTS
iv

ADVANTAGES OF DIRECT SEEDING ...................................................................................................................... 21

Lower Initial Cost ..................................................................................................................................................... 21

Flexibility................................................................................................................................................................... 21

Hard to Plant Species and Low-Quality Sites............................................................................................................ 22

Natural Root Systems ................................................................................................................................................ 22

DISADVANTAGES OF DIRECT SEEDING................................................................................................................ 22

Poor Control of Spacing and Stocking....................................................................................................................... 22

High Mortality on Droughty Soils............................................................................................................................. 22

Limited Use of Genetically Improved Seed Sources................................................................................................. 22

Limited Availability of Large, Open Sites................................................................................................................. 23

Less Effective Repellent Seed Coating...................................................................................................................... 23

Limited Availability of Personnel .............................................................................................................................. 23

ROLE OF SEEDING IN THE REFORESTATION OF THE SOUTH....................................................................... 23

Extent of Seeding Southern Pines.............................................................................................................................. 23

Evaluation of Seeded Stands...................................................................................................................................... 24

CURRENT APPLICATION OF DIRECT SEEDING TECHNOLOGY..................................................................... 24

Where Should Direct Seeding Be Used? ................................................................................................................... 24

What Species Are Best Suited For Direct Seeding? .................................................................................................. 25

What are Weather Constraints?.................................................................................................................................. 26

What Does Site Preparation Need To Accomplish?................................................................................................... 26

What Seed Treatments Are Needed?.......................................................................................................................... 26

When Should Seeds Be Sown? .................................................................................................................................. 27

How Are Seeds Distributed?...................................................................................................................................... 28

How Is Direct Seeding Success Determined?............................................................................................................ 28

CONCLUSIONS.............................................................................................................................................................. 28

ACKNOWLEDGMENTS................................................................................................................................................ 30

LITERATURE CITED ..................................................................................................................................................... 31
Abstract

Early in the 20th century the deforestation resulting from the “goldenage of lumbering” left millions of acres of forest land in the need for

reforestation. The challenge was so extreme that foresters of the early

1930s estimated that it would take 900 to 1,000 years at the then rate

of planting to reforest the denuded forest land that occurred throughout

the Nation. Forests of the West Gulf region were especially decimated

due to the development and use of steam-powered logging equipment

that left little capability for natural regeneration. Faced with this need,

scientists of the Southern Forest Experiment Station began an effort

to develop direct seeding with the hope of quickly seeding large open

areas of the South with southern pines. Protecting seeds from bird and

rodent predation was key to successful direct seeding, and in the mid1950s certain chemicals were found that made seeding an effective tool.

Additional components of a successful direct seeding operation were

increasing the availability of quality pine seeds, finding methods of

eliminating hardwood brush competition, and developing site preparation

treatments that favored seeding. This supporting research was essential

for the resulting successful restoration of millions of acres of southern

pine forests. Today, direct seeding is infrequently used, primarily due to

lack of large, open areas needing reforestation. But back then, seeding

met a significant need, and millions of acres of forest land were put back

into production.

Keywords: Chemical hardwood control, competition control,

precommercial thinning, reforestation, seed repellents, seed research, site

preparation, southern pines, stand stocking

THE NEED FOR DIRECT SEEDING 

TECHNOLOGY 

Much of the up to 90 million acres of longleaf pine (Pinus

palustris) occurring throughout the Coastal Plain of the

South were harvested by aggressive logging in the late

1800s and early 1900s. The longleaf forests of the Western

Gulf Coast region were particularly devastated by use of

steam-powered logging equipment that was developed

as the harvest of the forests of this region began. Railroads

extending into the flat land of the upland pine forests

brought log skidding and loading equipment that were

very efficient, but destroyed nearly all non-merchantable

trees as well as those harvested. This resulted in millions of

acres of cutover forests without the seed sources needed for

reforestation.

In 1954, Philip C. Wakeley, a scientist with the Forest

Service, U.S. Department of Agriculture estimated that

13 million acres across the South were currently in need

of reforestation (Wakeley 1954). When the Alexandria

Research Center (ARC) was established following World

War II, the territory served by ARC covered over 7 million

acres in central and southwestern Louisiana and east Texas.

Almost 80 percent was commercial forest land and nearly

half of that once supported magnificent stands of virgin

longleaf pine. Over 20 percent (1,250,000 acres) was barren

of pines, and another 3 million acres were much below full

potential of the land because it was largely covered by scrub

oaks and other low-value hardwoods (Cassidy and Mann

1954).

It was estimated that if the treeless longleaf pine land in

Louisiana and Texas was reforested by planting nursery

grown seedlings, the job would take 50 or more years at

the rate feasible with the then current nursery capability

(Cassidy and Mann 1954). There was a significant need

to develop additional technology to meet this awesome

reforestation project. Although expanding bareroot

Direct Seeding Southern Pines: 

History and Status of a Technique 

Developed for Restoring Cutover Forests

James P. Barnett

Steam-powered skidders manufactured by the Clyde Ironworks in

Duluth, MN, greatly increased logging capability in the early 1900s.
2

nursery capacity was an obvious goal, another option was

development of a direct seeding capability.

EARLY SEEDING ATTEMPTS

Direct seeding had been considered for generations as a

potential forest regeneration technique. The sowing of

tree seeds on prepared forest soils was often considered and

tried—and sometimes the trials met with success. Barnett

(2011) describes Great Southern Lumber Company’s hand

seeding in 1920 of slash pine (P. elliottii) on furrows plowed

by teams of mules. An 800-acre tract was successfully

regenerated and is considered the first successful

commercial direct seeding in the United States.

Great Southern Lumber Company’s head ranger, F.O.

“Red” Bateman, was responsible for this seeding operation.

Other seeding trials were not successful, however, and

Bateman was quoted as describing to young research

foresters his evaluation of the potential of direct seeding:

When we went out to start seeding, there was

a pheelock [field lark or meadowlark] sittin’

on a fence, he whistled, and up come fifty more

feellocks. We went down the furrows, dropping

longleaf seeds every six feet. The pheelock 

follered us down the furrows, and, gentlemen,

when we got to the end of the furrows, there

wasn’t a damn thing left in the furrows but birdsh-t! (Wakeley 1976).

INITIATION OF A SEEDING 

RESEARCH PROGRAM 

In 1946, the Southern Forest Experiment Station

established the ARC in central Louisiana. The mission

of the ARC was to develop improved methods of

reforestation and management to guide landowners in

the task of attaining optimum production and income from

their forest land. When established, five areas of research

were selected in consultation with the Center’s Research

Advisory Committee:

Top: Old-growth longleaf pine stands like this occupied about 90

million acres across the South’s Coastal Plain when settlers arrived.

Bottom: This area became a part of the Palustris Experimental

Forest and represented millions of acres of cutover forests across

the South. 

Top: In 1920, the Great Southern Lumber Company reforestation

efforts began with this direct seeding of slash pine on sites created

by plowing furrows. Bottom: This is the 800-acre slash pine

plantation 5 years following direct seeding into furrows plowed by

mules.
3

(1) Reforesting the cutover lands.

(2) Managing pine plantations for optimum returns.

(3) Controlling low-value hardwoods with 

chemicals.

(4) Improving management of livestock and forage 

on forest ranges.

(5) Determining costs and returns of good forest 

management.

Of these, the highest priority was in developing and

improving techniques to reforest cutover pine lands

(Cassidy and Mann 1954).

Derr (1958) justified the direct seeding effort based on

four rationales. First, direct seeding was seen as fast and

required minimum labor. He reasoned that one man with a

planting tool could plant, if his back held out, 1 acre of pine

seedlings per day. With a planting machine, he could plant

5 to 6 acres per day. But, with aerial seeding, a pilot could

seed 1,000 acres in 1 day.

The second reason for seeding was that it was cheaper.

While the cost fluctuated with cost of seed, it did not

exceed $10 per acre. Planting seedlings cost at least

twice that amount.

Third, seeding provided for denser stands—a result that

was better for longleaf pine—than did planting of bareroot

seedlings. While this later turned out to be an undesirable

outcome, originally dense stands of longleaf seedlings

were desired to overcome seedling losses during the

grass stage of the species. Most longleaf pine sites to be

reforested had a serious infestation of brown-spot needle

blight (Mycosphaerella dearnessii, previously Scirrhia

acicola) that remained from the earlier stands and resulted

in significant seedling mortality. Direct seeding was seen as

a significant new method for reforesting longleaf pine. In

the early 1950s, <100 acres of longleaf pine seedlings were

planted each year (Mann 1956).

Finally, direct seeding could be expanded quickly to take

advantage of bumper seed crops. At that time, storage of

longleaf pine seeds was problematic.

Because direct seeding promised to be cheaper, faster, and

more efficient than planting, it became a major research

project of the ARC. By 1954, about 3,000 acres in direct

seeding experiments were conducted using longleaf, slash,

and loblolly (P. taeda) pines. No successful method of

application had been found, but the major causes of failure

had been identified (Cassidy and Mann 1954).

Seed-eating birds, chiefly eastern meadowlarks (Sturnella

magna) and field sparrows (Spizella pusilla) were the

greatest problem. The vast areas of cutover forests provided

the ideal habitat for large flocks of these birds (Burleigh

1938). Research indicated that coating the seeds with a

chemical repellent was a promising technique. Rodents, too,

were predatory, but for fall-sown longleaf pine the menace

was less than from the birds.

The direct seeding research initiative was led by Harold

J. Derr and William F. Mann, Jr. Derr was the scientist

assigned to the project, and Mann, who was the Center

Leader, supervised and participated in the effort. 

DEVELOPMENT OF REPELLANTS

Early in the evaluations of direct seeding, predator control

by men patrolling with shot guns was the only practical

method of reducing losses of seeds to birds—mostly large

flocks of migrant species. A minimum of a one-man shotgun

patrol was assigned to each 200 acres of seeding for at least

8 hours per day during the 5-week germination period. Even

this expensive measure was not always effective (Mann

1956, Mann and Derr 1955).

Bird Repellents 

In 1953 and 1954, tests began with a chemical bird

repellent called Morkit® which was used to coat the seed

(Mann and Derr 1955). Morkit® was manufactured in

Germany and consisted of a mixture of anthraquinone

and inert ingredients.

A cooperative effort between scientists of the ARC and

U.S. Fish and Wildlife Service evaluated Morkit® and

related anthraquinone compounds. Anthraquinone is

The cutover forests provided ideal habitat for flocks of eastern

meadowlarks which ate huge quantities of seeds.
4

environmentally safe and is used in numerous compounds

such as dyes, laxatives, and cosmetic products. Previous

tests evaluated other compounds and colored seed

coatings, none of which were effective repellents for

southern pine seeds.

Tests showed that seeds treated with Morkit® yielded 4,500

seedlings per acre, and untreated seeds only 195 (Mann

and Derr 1955). In 1954, a large-scaled test of Morkit® and

anthraquinone compounds showed them equally effective;

each yielded about 3,000 seedlings per acre. Untreated

seeds produced only about 250 seedlings per acre. Birds

consumed 90 percent of the untreated seeds in 11 days.

Morkit® was withdrawn from the United States market

in 1955 and additional tests with U.S. Fish and Wildlife

Service scientists found that Arasan Seed Disinfectant and

Protectant® (50 percent tetramethyl thiuram disulphide),

now marketed as thiram, was equally effective as

anthraquinone compounds in repelling birds (Meanley and

others 1957). Caged tests determined that birds did not eat

seeds treated with these chemicals and that the treatments

stopped predation. Also, Mann and others (1956) noted that

thiram had some rodent-repellent qualities. Because of the

rodent repellency aspect of Arasan® (thiram), it replaced

anthraquinone as the preferred seed treatment. It did,

however, have some problems—it irritated the eyes,

nose, and throat. It also had a negative effect on seed

germination when laboratory tests were conducted in

closed germination dishes.

Thiram 42-S®, a liquid formulation, later became the

preferred formulation to use in direct seeding because it

provided a durable, dust-free coating that was superior

to any previous formulation (Mann 1970). It is also an

effective, registered fungicide formulation frequently used

as a seed treatment to control seedborne microorganisms

and continues to be registered as a tree seed treatment for

bird repellency.

Rodent Repellents

Although early studies found that birds were the primary

predators of pine seeds, these tests were conducted with

longleaf pine seeds sown in the fall (November and early

December) on sites with a light grass rough (Derr 1958,

Mann 1956). Longleaf seeds lack dormancy and germinate

soon after natural dispersal in the fall. When more dormant

seeds of pine species that require stratification were sown

in the spring, they were found to be subject to heavy rodent

predation because rodent populations increase during the

winter and early spring.

As early as 1956, Mann (1956) found that seeds sown in

late December and early spring needed protection from

rodents. Cooperative studies with scientists of the U.S.

Fish and Wildlife Service were conducted to find chemicals

that would reduce the losses from rodents. Even though

Arasan® provided some protection from rodents, adding

the chemical endrin to the seed coating greatly improved

seeding success when seeds were sown later in the winter

(Derr and Mann 1959).

Endrin 50W®, sold mainly as an insecticide, was a potent

chlorinated hydrocarbon poison and presented a hazard to

the environment and animal life. All who used the chemical

were required to wear a respirator and rubber gloves and

change and wash their clothes daily. Although incorporating

endrin into the repellent coating significantly increased

seeding success, it caused concern because of its extreme

toxicity. It typically was added to the other chemicals at

a rate of 1 pound (0.5 pound active ingredient) per 100

pounds of seeds (Derr and Mann 1959, Mann 1958).

There was some question whether endrin was truly a

repellent or if it killed the rodents that ate the seeds.

Evaluations seemed to confirm the hypothesis that rodents

ate some of the treated seeds, became sick, and then avoided

continued predation. In the early 1970s, however, public

concern about the use of many extremely toxic chemicals

Top: Harold J. Derr standing beside slash pine saplings established

by direct seeding. Bottom: Longleaf pine seeds treated with repellent

coatings consisting of Arasan 75®, latex, and aluminum flakes.
5

in agriculture caused the Environmental Protection Agency

(EPA) and the U.S. Department of Agriculture (USDA)

to begin a program to review the registration of such

chemicals. Endrin was high on the list of chemicals to be

reviewed and James P. Barnett of the ARC was selected to

lead the multi-agency USDA team to conduct a benefit/risk

assessment of the chemical.

The assessment recommended (Barnett and others

1977)—and the EPA accepted—continued use of endrin in

forestry direct seeding primarily due to the small amount

distributed to any acre of land during seeding. Other uses,

which accounted for most of the market for the chemical,

were generally not approved. As the result, although still

registered by the EPA for the direct seeding application, the

product was removed from the market in the United States

by the manufacturer.

When availability of endrin ended, the use of direct seeding

began to decline—large, open sites where its use was

best suited were generally not available. So, although the

need for a rodent repellent lessened, an effort was made to

find a chemical with rodent repellency that could replace

endrin. Campbell (1981a) and Barnett (1995) evaluated

several possible chemicals, but none were found that were

environmentally safe as well as effective.

More recently, field tests have shown that the substance

oleoresin capsicum has promise as a rodent repellent

(Barnett 1998). Capsicum is obtained from dried cayenne

peppers (Capsicum frutescens) and is standardized with

olive oil. The chemical in capsicum that can produce a

burning sensation in the mouth is capsaicin. Its strength is

measured in parts per million (ppm). The ppm are converted

to Scoville Units (SV), the industry standard for measuring

the heat of peppers (American Spice Trade Association

1960, Hoffman and Lego 1983). One ppm is equivalent to

15 SV. The material in this study had an SV of 500,000.

Although capsicum is a natural and nontoxic chemical

derived from pepper plants and is used in many foodstuffs

to increase their pungency, it is an irritant to the skin and

eyes. Protective gloves and eyewear are recommended

when using concentrated forms of this product.

Nolte and Barnett (2000) evaluated the efficacy of thiramcapsicum treatments to house (Mus musculus) and deer

(Peromyscus maniculatus) mice that cause damage to

longleaf pine seeds. The combination of thiram and

capsicum was found to protect seeds from deer mice and

is a potential repellent to protect pine seeds from rodent

predation when used in direct seeding. 

Chemicals to Aid Coating Applications

Another aspect of the collaboration with the U.S. Fish

and Wildlife Service was to identify chemicals that could

be used as a sticker for coating repellents on seeds. Early

on, Flintkote C-13-HPC®, an asphalt emulsion, was found

to effectively bind the coating material to seeds (Mann

1958). Additional studies found that Dow Latex 512-R®

was equally effective (Mann 1959). The latex product

soon became the one used routinely in repellent treatments

because it could be more easily applied to seeds.

James P. “Jim” Barnett led

the cooperative effort to

maintain the registration of

endrin.

A germinated longleaf pine seed coated with the

thiram-endrin repellent.
6

Fifteen tablespoons of aluminum powder is typically

applied to the repellent mixture for 100 pounds of seeds

to increase the flow of the seeds through seed-sowing

equipment (Derr and Mann 1959).

Seed Coating Techniques 

Repellent treatments evolved over time. Early in the

development of repellents, anthraquinone and Arasan®

became effective treatments. These were applied as a

powder formulation and at the rate of 15 percent by weight

(15 pounds per 100 pounds of seeds); when Arasan-75®

became available it could be used at 10 percent because of

its higher concentration of active ingredients (Derr 1958).

All of these treatments were applied as an overcoating after

the seeds were immersed in an adhesive solution of either

asphalt emulsion or latex in water.

The asphalt adhesive Flintkote C-13-HPC® was diluted in

water with a ratio of 1:3, whereas Dow Latex 512-R® was

mixed with water in the ratio of 1:9.

Repellents were evaluated over time and modified to

take advantage of improved formulations. They were

standardized using a water suspension of thiram marketed

as Arasan-42S®, Dow Latex 512-R®, and Endrin-50W®

(Derr and Mann 1971). The repellent mixture consists of

1 gallon of thiram, 5 fluid ounces of latex, and 1⁄2 pound

of endrin. This mixture usually treats about 50 pounds of

seeds, but the amount treated will vary by pine species.

About 8 tablespoons of aluminum powder are typically

added to ensure the flow of seeds through sowing

equipment.

Once the seeds are treated they are spread on polyethylene

sheeting to dry for about 30 minutes.

SEED QUALITY AND QUANTITY

A significant problem in the development of direct

seeding as a forest regeneration technique was access to

large quantities of pine seeds. This was particularly true

for sowing longleaf pine seeds since there was lack of

information on successfully collecting, processing, treating,

and storing these seeds. Initially, longleaf pine seeds were

thought to be viable only if freshly collected, so, availability

of seeds was limited by the size of the annual cone crop.

Since research was needed to provide guidelines for

seed production and storage, in 1957, Bobbie F. “Mac”

B.F. McLemore was hired to begin a research program in

seed science that would support direct seeding and nursery

research efforts.

Forestry technician, Tommy Rhame, demonstrating seed treatment

used early in the development of direct seeding.

Tommy Melder mixing latex into an Arasan-42S® repellent

formulation.
7

McLemore was recruited to begin a research program in

seed science. In 1961, James P. “Jim” Barnett was added to

the staff to assist in the seed research program.

Procurement

Amounts of southern pine seeds were insufficient to

meet increasing needs for direct seeding; therefore, many

landowners began to collect cones for processing. As seed

dealers became established, cone and seed processing was

typically contracted.

Various questions related to cone collecting times, cone

handling, and seed processing were addressed. Procurement

of local sources of seeds was generally recommended, but

with the infrequency of cone crops, seed zones began to

be developed to provide guidance on appropriate locations

for collection (Wells 1969). Studies that followed have

provided collection guidelines for all major southern

pines (Schmidtling 2001).

Establishment of forest seed dealers, such as the pioneering

American Forest Seed Company (AFSC), provided a

needed resource in meeting the needs for direct seeding.

Howell Cobb of the AFSC developed early commercial

collection, processing, treating, and storing services (Barnett

2011). The leadership of Derwood Delaney, the operations

manager of the AFSC, later led to the development of the

Louisiana Forest Seed Company, a premier forest seed

provider (Barnett and Burns 2011). 

Collection and Processing

The dilemma of inadequate amounts of quality longleaf pine

seed, as well as for other southern pine species, resulted

in creation of a seed research program of wide scope. The

timing and location of cone collections and cone handling

and processing techniques needed to maintain high seed

quality were important issues to be resolved. Although

Wakeley (1954) had developed some cone maturity

guidelines, the demand for huge quantities of seeds resulting

from direct seeding required better data on timing of cone

collection—both its initiation and length.

Estimating cone and seed production—Direct seeding

and increasing nursery production required the production

of large quantities of high quality seeds. Seed collectors

needed methods to determine where and when to collect

cones. A number of studies provided guidelines on how

to provide early estimates of annual cone production.

Techniques for such estimation were based on counting

numbers of female flowers or strobili in the spring about 18

months before cone maturity (Croker 1971, Fatzinger and

others 1988) and binocular counts of cones a few months

before cone ripening (Wasser and Dierauf 1979, Webb and

Hunt 1965, Wenger 1953). The counting of strobili provided

less accurate predictions of cone production than estimates

based on binocular counts of cones (Shoulders 1968).

Although knowing the size of the cone crop is important,

equally significant is information on the seed yields per

bushel of cones collected (Bramlett and Hutchinson 1964).

This information allows collectors and buyers to estimate

cone requirements before collection starts and concentrate

picking in areas where seed yields are highest.

Derwood Delaney (center) with sons John (left) and Gary (right)

provide a full range of forest seed capabilities through their

Louisiana Forest Seed Company.

A sliced longleaf pine cone showing exposed seeds that become the

basis for predicting the seed yields of southern pines.
8

The idea of cutting sample cones and counting exposed

seeds as an index of seed yields had been suggested for

many years (Hopkins 1956, Syverson 1960). McLemore

(1961a) used the cone-cutting procedure to develop

relationships between the numbers of seeds exposed by

slicing and the total number of sound seeds per cone. With

the additional information on the number of seeds per

pound and number of cones per bushel, McLemore (1962)

published methods for projecting seed yields per bushel of

collected cones for longleaf, slash, and loblolly pine.

McLemore’s techniques, summarized later by Barnett

(1999), became widely used by seed dealers in determining

where and when to make cone collections.

Cone specific gravity measurement—Specific gravity

(SG), computed by dividing cone weight by the weight of

water the cone displaces, is the most reliable method of

determining cone maturity in southern pines. For decades,

Wakeley’s (1954) method of floating cones in SAE 20

motor oil (SG of 0.88) simplified cone specific gravity

determinations. When cones floated in the oil, they had

reached the point where their scales would open when

collected and dried. Extension of the collection period

became possible with lengthening cone storage times, but

the need for a simple technique to measure SG was needed.

Barnett (1979a) published a simplified flotation procedure

developed by B.F. McLemore for determining cone SG in

the field. Graduated cylinders of a size to accommodate

species differences in cone size are filled to a convenient

level with water and the level noted. When a cone is added

to the cylinder, the difference between the water levels

provides a measurement of cone weight. If the cone sinks

the SG is greater than 1.0 and cannot be measured. The

water level of floating cones submerged by a wire or small

stick is noted. The difference between this and the initial

level provides a measurement of cone volume. The division

of cone weight by cone volume provides SG.

Cone/seed maturity relationships—Until seeds disperse

from cones on trees, germination of longleaf pine seeds

increases as cone specific gravity decreases (McLemore

1959). Once collected, longleaf seeds do not continue to

mature in cone storage, and cone storage decreases seed

viability unless collections are delayed until natural cone

opening is imminent (Barnett 1976a). Even though seed

yields increase with cone storage, storing cones more than

30 days reduces storability of the seeds (McLemore 1961b).

In contrast, viability of slash pine seeds continues to

increase during storage of harvested cones if the cones are

fully mature when picked. Loblolly pine seeds mature (will

germinate) before seed yields indicate cones are ripe, and

more than 95 percent of loblolly seeds are viable before

they can be extracted. In order to obtain both optimum seed

yield and seed quality, efforts to determine the relationship

between indices of cone maturity and seed maturity were

evaluated (Barnett 1976a, 1979b). These studies evaluating

the relation of cone ripening and seed maturity provided the

information needed to lengthen the cone collection period,

and it was extended for all the major southern pine species.

Overcoming processing problems—Longleaf pine seeds

are the most difficult of the southern pines to collect,

process, store, and treat successfully. Because the seeds

are large, have thin seedcoats, and are usually moist

when extracted from cones, collecting and processing

them without adversely affecting quality requires special

handling procedures.

Ripening immature or holding mature longleaf cones before

extraction may or may not improve seed viability (Barnett

1976a, Bonner 1987, McLemore 1975), but some cone

storage is needed to improve seed yields (Barnett 1996).

During the processing stage, dewinging of longleaf seeds

may adversely affect the quality of seeds extracted from

mature cones. The possible causes of dewinging damage

are lack of seed drying, inappropriate dewinging equipment,

and large-sized seeds. Drying seed prior to dewinging

results in more brittle wings that are quickly and easily

reduced to stubs (Barnett 1996). However, excessive drying

at high temperatures may also reduce seed quality.

Longleaf pine seeds require dewinging equipment designed

for more sensitive seeds. Many tests have shown that the

harshness and length of dewinging must be minimized.

Equipment used for dewinging loblolly or slash pine

Early cone collections were made by climbing trees and dislodging

cones with a hooked pole.
9

is usually inappropriate for longleaf pine (Barnett and

Pesacreta 1993).

Once dewinged and dried, longleaf seedlots often have

significant quantities of empty or partially filled seeds.

Density-gravity tables offer the best option for removing

empty seeds from large-sized seedlots. With smaller lots

typically used in research projects, flotation in the chemical

pentane is very effective (McLemore 1965).

In addition to longleaf seeds being large, they also have

seedcoats that are fibrous and can carry significant

populations of pathogenic fungi (Barnett and Pesacreta

1993, Pawuk 1978). Germination of less vigorous seeds

may be improved by treating with a sterilant, such as

hydrogen peroxide (Barnett 1976c), or applying a fungicidal

drench that reduces Fusarium and Pythium populations

(Barnett and Pesacreta 1993). 

As technology for producing and handling longleaf pine

seeds advanced, research on other pine species began so

they could be handled equally well. In most situations, seeds

of the other southern pines were more easily collected,

processed, and stored than for longleaf pine.

Seed Storage and Testing

Storing longleaf pine seeds was a significant problem

and subject to numerous studies. Early in the program,

guidelines for successfully storing longleaf seeds were

developed—drying to 8–10 percent moisture content

and holding at subfreezing temperatures of 25 oF (-4 oC)

or lower (Barnett 1969, Barnett and McLemore 1970,

McLemore 1961c).

Longleaf pine seeds of good quality can be stored without

significant losses in viability for at least 20 years, if held

under the recommended conditions of low-seed moisture

contents and storage temperatures (Barnett 1969, Barnett

and Jones 1993). Other species can be held for longer

periods. Slash and shortleaf (P. echinata) pine seeds have

remained viable for up to 50 years when held under less

than ideal conditions (Barnett and Vozzo 1985, Wakeley

and Barnett 1968).

To evaluate if seeds stored for 7 years would perform well

when direct seeded, Barnett (1964) conducted a series of

studies and determined that stored seeds performed equally

well as freshly collected seeds.

Testing is critical when using stored seeds. Although seeds

can be tested at an organization’s facility, the Eastern Tree

Seed Laboratory at Dry Branch, GA, was established by

the Forest Service in the early 1950s to provide this service.

Now expanded to be the National Tree Seed Laboratory

(NTSL), it provides for standardized and internationally

recognized seed testing capability for forest tree and

understory plant seeds. This service is particularly important

as a third-party evaluation to meet the need for international

sales and to resolve potential conflicts of interest.

Testing should be done soon after collecting and processing

to determine initial seed quality. Also, seeds in storage

should be tested periodically to determine if seeds are

losing viability or vigor. Especially, stored seeds should be

evaluated prior to use to establish appropriate sowing rates

based on the quality of the seeds. The NTSL will provide

these tests for a reasonable fee.

Longleaf pine cones collected and held in crates,

awaiting processing.

Testing southern pine seeds for germination potential.

(Photo courtesy of Weyerhaeuser Company)
10

Storing Repellent-Treated Seeds

Seeding operations should be carefully scheduled to

minimize time between seed treating and sowing.

Sometimes delays are unavoidable, especially when seeds

must be shipped or there are interruptions in time of sowing.

Seeds treated with repellents can be held for several weeks

in a well-ventilated, unheated space or in a cold room at any

temperature down to 0 oF (-18 oC). If seeds must be kept

until the following year, they should be dried to 10 percent

moisture content and stored between 0 oF (-18 oC) and 25 oF

(-4 oC). The repellent coating will not lose its effectiveness

even after 1 year of storage (Barnett and McLemore 1966,

McLemore and Barnett 1966).

Stratification

In nature, longleaf pine seeds germinate in the fall soon

after release from cones and are generally considered

nondormant and do not require stratification or prechilling

treatments (Mann 1970). However, some evaluations

indicate an increase in speed of germination as a result

of such treatment (Karrfalt 1988). Other studies show a

potential reduction in total germination as a result of just 14

days of stratification (Barnett and Pesacreta 1993).

So, stratification is not generally recommended for

longleaf pine.

Other southern pine species exhibit some level of dormancy.

Studies to determine the nature of dormancy in these seeds

indicate that the proportion of the weight of the seed coat

to total seed weight is closely related to level of dormancy

(Barnett 1972). Seeds of loblolly pine are the most dormant

of southern pine species and seeds from more northern and

eastern sources exhibit the deepest dormancy

(Barnett 1976b, 1991).

McLemore began a series of studies to develop

recommendations for preparing loblolly pine seeds for

sowing. Early evaluations indicated that a minimum of 30

days of stratification were needed to ensure prompt and

complete germination when seeds are sown in the early

spring (McLemore and Czabator 1961).

Aerated soaks are an approach to hastening germination of

dormant seeds when time is lacking for lengthy stratification

procedures. While not as effective as stratification, speed

of germination can be significantly improved by using

aerated soaks (Barnett 1971).

Information on the current knowledge on how to collect,

process, treat, and store longleaf pine seeds has been

summarized by Barnett and McGilvary (2002).

WHERE AND WHAT TO SEED

Where to Seed

Direct seeding was developed for use on forest lands that

generally fall into two categories: (1) open lands, or (2)

those partially or wholly occupied by brush and low-value

hardwoods (Derr and Mann 1971).

Open areas typically have a grass sod cover, and these

areas were often seeded with longleaf, loblolly, or slash

pines. Such sites are relatively inexpensive to plant with

bareroot seedlings, but seeding large acreages was faster

and prompted many such operations. Seeding of longleaf

pine, which is difficult to successfully plant with bareroot

stock, was found to be an effective means of regenerating

this species.

Direct seeding was also found to be useful in restocking

stands destroyed by wildfire and wind storms. Salvage

cutting of resulting dead timber typically scarifies the soil,

creating an excellent seedbed.

In the 1950s, many pine sites were occupied by brush and

hardwoods. Although such sites were ideal for reforestation,

the low-value hardwoods needed to be destroyed by either

mechanical or chemical treatments (Wheeler and Cassady

1956). Once the hardwoods were killed, the areas could be

seeded without removal of the dead debris.

An industrial forester for T.L. James Company evaluating a cutover

site for its potential for direct seeding. 
11

Other sites where seeding was effectively used included

mountainous soils that are often rocky, spoil banks left after

strip mining, and heavy clay soils that are difficult to plant.

Some soil or terrain conditions are unsuitable for direct

seeding or may require special treatment. These areas

include tracts of deep upland sandy soils or areas in the

extreme western portion of the pine range where the soil

surface dries so rapidly that moisture is inadequate to

sustain germination of broadcast-sown seed (Derr and

Mann 1971). On such sites, the seeds must be covered

with 1⁄2 to 3⁄4 inch of soil to obtain germination and sustain

seedling growth (Hodges and Scheer 1962, Jones 1963,

Shipman 1963).

Sowing should not be attempted on poorly drained sites

where seed or seedlings will be under water for more than 1

or 2 weeks (McReynolds 1960, Miller 1957).

In summary, sites suitable for seeding include most of

those available for commercial pine production in the

South. Among these sites are wide variations in soils and

conditions. Usually, some site preparation is needed, but it

may vary from intensive treatments that are essential for

survival and growth to simple methods used primarily for

increasing initial stocking levels (Derr and Mann 1971).

What Species to Seed

The need for regenerating large areas of cutover longleaf

pine forests was the driving force for developing direct

seeding technology. It is not surprising then that longleaf

was the desired species for regenerating many sites across

the South. However, lack of seed availability limited its

use for years. Some landowners, too, preferred using other

species because of the slow initiation of height growth of

longleaf pine.

Loblolly pine, then, became widely used in seeding

operations in the upper Coastal Plain (Mann and Derr

1961), and slash pine was generally used in the coastal

flatwoods (Mann and Derr 1964). Wells (1969) and

Shoulders and Tiarks (1980) did much to establish

guidelines for species selection on specific soil types.

Basic direct-seeding procedures do not vary greatly from

species to species. The same repellent formulation can be

used and sowing methods are essentially alike. There are,

however, species differences in fruiting habits, seed size,

seed dormancy, and site requirements that affect sowing

procedures. These and other relevant species characteristics

that affect seeding are discussed by Derr and Mann (1971).

SITES AND SEEDBED PREPARATION

Selecting sites to be seeded to pines and choosing

presowing treatments are closely related tasks. Methods

vary in cost and intensity, but in most cases conditions on

the site determine the methods to be used.

Site preparation for direct seeding has two objectives: (1)

to expose the mineral soil that seeds need for germination,

and (2) to control competing vegetation that will interfere

with the survival and growth of the new stands (Boggs and

Wittwer 1993, Derr and Mann 1971).

Fire is the simplest and least expensive method of site

preparation, and on open sites it is often sufficient. On areas

with hardwood brush and trees, it typically is combined

with mechanical or chemical treatments. Whatever means

are chosen, fairly complete removal of competing hardwood

trees is usually needed and the likelihood of sprout growth

must be considered. To control trees large enough to be

treated individually, chemical application methods, such

as tree injectors and basal sprays, were developed (Peevy

1960, 1961). Dense stands of small stems were usually

eliminated by mechanical treatments or in some instances

by chemical spraying treatments (Peevy and Burns 1959).

Prescribed Fire

Prescribed or controlled burns are an option on most sites

and may be the only treatment needed for open, grassy sites.

The light grass rough that develops several months after the

fire provides a better germination environment for longleaf

pine than does newly burned sites (Derr and Mann 1959).

Successful seeding of loblolly pine on a mine spoil bank in north

Alabama.
12

Exposure of mineral soil is a desired effect from a

presowing burn, but for longleaf pine there are additional

benefits. For example, fire removes foliage infected with

brown-spot needle disease, which can develop on sites

where grass-stage seedlings from previous stands exist.

A single burn will reduce competition, but will not provide

sufficient control of small hardwoods and brush.

Sprouting regrowth is often rapid and may require

additional treatment.

Disking

Disking became a more intensive treatment for seeding

open, grassy sites and where palmetto (Sabal adans) and

gallberry (Ilex coriacea) were abundant. In such open

sites, disking confined to strips, separated by 6- to 7-foot

undisked areas, was a very effective treatment.

Several studies with longleaf, slash, and loblolly pine

demonstrated that disking markedly improved survival

in dry years (Derr and Mann 1971, Lohrey 1974). Early

seedling growth of loblolly and slash pine was also

improved by disking. After 10 years, however, this initial

growth advantage was lost (Haywood 1983).

Disking elevated seed beds, or mounding, became a

common practice on flatwood sites where water tables are

high. Seeding on these areas resulted in improved seedling

survival and early height growth as a result of removal of

competing vegetation (Russell and Rhame 1961),

but frequently there was no long-term benefit (Mann

and Derr 1970).

Simple broadcast sowing is effective on disked ground,

but more cost-effective treatments can be achieved with

machines that drop seeds in rows and have packing wheels

that put them into firm contact with the soil.

Amelioration

Direct seeding techniques were extended to sites that

required modification for optimum growth of pines. These

treatments, sometimes referred to as site amelioration,

include drainage, high bedding, and creation of artificial

tussocks. These were developed to improve seeding

performance in low coastal areas and other places where

drainage is slow and water tables are high during much of

the year (Jarvis and Beers 1965).

Drainage was shown to result in a striking growth

response on water-logged sites. High bedding, or

mounding, is an intensive disking treatment done with

equipment that elevates the seedbed by 5 or 6 inches. Top: Prescribed burning became a primary practice for reducing

vegetative competition prior to seeding. Bottom: Row seeding with

a tractor-drawn disk seeder and packing wheel developed by the T.L.

James Company.
13

Bedding became a popular method of removing excess

water from the rooting zone and improving soil aeration.

Growth response to bedding was found to vary significantly

(Derr and Mann 1977, Mann and Derr 1970), largely

because of differences in the amount of well-aerated soil

bedding provides during the wet winter period (McKee and

Shoulders 1970, 1974).

For 8-year-old slash pine, beds that raised the rooting zone

18 inches or more above the water table during January

and February were effective in promoting tree growth,

whereas beds that raised the soil <18 inches resulted in less

aboveground biomass (Shoulders and McKee 1973).

Site preparation treatments, such as disking and mounding,

typically improve seeding and planting success and early

growth primarily by reducing competition from herbaceous

vegetation (Tiarks and Haywood 1981).

Control of Competing Vegetation

Even before the development of direct seeding, the need for

chemical treatments for controlling undesired, low-grade

hardwoods became a research focus (Cassady and Mann

1954). Much of the forest land in the West Gulf region

not completely devoid of trees was covered with nonmerchantable scrub hardwoods, and removal of this material

was critical for restoring productive pine forests.

Fred A. Peevy, first employee of the ARC in 1946, was

responsible for developing chemical control techniques

for these low-quality trees—primarily blackjack oak

(Quercus marilandica), post oak (Q. stellata), red oak

(Q. falcata), sweetgum (Liquidamber styraciflua), and

hickory (Carya spp.).

Ammate® was an early chemical that Peevy (1947)

developed methodologies for use in forestry. Soon,

Ammate® was replaced by the agricultural chemicals

2,4-D® and 2,4,5T®. These became the mainstay forestry

treatments for a number of years (Peevy 1960, 1961).

As environmental problems became evident with these

chemicals, Peevy began to evaluate a number of newer and

safer products and developed recommendations for using

them for control of a range of upland hardwood species.

Peevy’s pioneering research was applied quickly into the

direct seeding programs. Seeding of sites converted from

low-quality hardwoods was accomplished by sowing seeds

as the hardwoods were killed by chemical treatments.

Use of direct seeding was a particularly effective method

of converting these sites to pines because the deadened

standing hardwood timber did not have to be removed. Top: High bedding or mounding became a common practice to

prepare wet sites for seeding or planting. Bottom: Fred A. Peevy

applying a chemical basal spray to a blackjack oak.
14

TIMING AND SOWING RATES

There are two distinct sowing seasons—spring and fall.

Fall sowing is generally recommended for longleaf pine.

Seeds of the other major southern pines that exhibit some

dormancy—loblolly, slash, and shortleaf—are best sown in

the spring after stratification.

The best time for fall sowing of longleaf pine is at an early

date after natural seedfall when the soil has been recharged

by 2 to 4 inches of rain (Derr and Mann 1971). If rains

are delayed, longleaf can be sown well into December.

Longleaf will germinate throughout winter, but cold weather

slows the process and lowers seedling yields.

For species sown in the spring, timing is defined as

the transition period between winter dormancy and

appearance of new foliage—about the time first blooms

appear on red bud (Cercis canadensis) and red maple

(Acer rubrum) trees (Derr and Mann 1971). Stratified

seeds sown in mid-February usually complete germination

by mid-April. Delays in sowing may adversely affect results

(Hatchell 1966).

Sowing rates vary considerably, even within a species, by

quality of the seeds, method of sowing, and stocking desired

by the landowner.

General recommendations for broadcast seeding are about 3

pounds of seed per acre for longleaf pine, 1 pound for slash

and loblolly, and 0.5 pound for shortleaf (table 1). These

provide rates between 12,000 and 20,000 viable seeds per

acre and result in initial stands ranging between 2,000 and

5,000 seedlings per acre. For sowing rows or spots, the rates

should be much less (table 1).

A difficulty in broadcast seeding is the frequent

overstocking of the resulting stands. The stocking levels

vary considerably by environmental conditions and

degree of site preparation, as well as seed quality and

preconditioning. If there is experience in seeding similar

areas to those proposed, the sowing rate may be adjusted

downward. The frequent need for precommercial thinning

resulted in techniques developed to reduce overstocking by

sowing disked strips, rows, and for small landowners, spots

(Lohrey 1970, Mann and Burns 1965). 

SEED DISTRIBUTION

Sowing pine seeds can be accomplished by a number of

methods depending on the size of the area to be seeded and

the availability of specialized sowing equipment. Seeds of

different species vary considerably in flow characteristics

through seeding equipment. The shape of pine seeds affect

flow and dewinged longleaf seeds are particularly difficult

due to the adherence of the wing to the seed coat; it is

broken off during processing, and a wing stub results. In an

attempt to improve the flow, aluminum flakes were added to

the repellent seed treatment (Derr 1964).

Pelleting of pine seeds was evaluated in an attempt to

improve flow characteristics for use in seeding equipment.

The results of these trials indicated that the pelleting

material had an adverse effect on germination due to

the amount of material needed to obtain round pelleted

seeds and the epigeal nature of pine seed germination (the

germinating seed is raised by the root radicle growing into

the soil).

Table 1—Average number of seeds per pound and suggested sowing rates per acre

Species

Seeds 

per

pounda

Weight of dry seeds per acre for seeding

Broadcast Rowsb Spotsc

No. Lbs. No. Lbs. No. Lbs. 

Longleaf pine 4,700 15,000 3.24 2,900 0.63 4,350 0.94

Slash pine 14,500 14,000 1.11 2,900 0.23 4,350 0.35

Loblolly pine 18,400 12,000 0.75 2,150 0.14 3,650 0.23

Shortleaf pine 48,000 20,000 0.48 4,350 0.10 5,800 0.14

aDry, untreated seed, with viability of 95 to 100 percent: averages from Wakeley (1954).

b Rows 10 feet apart for all species. Spacing within rows: 1.5 feet for longleaf and slash, 2.0 feet for loblolly, 

and 1.0 feet for shortleaf. 

c Spots spaced 6 x 10 feet, 6 seeds per spot for longleaf and slash, 5 per spot for loblolly, and 8 per spot 

for shortleaf. 

 Source: Campbell (1982b).
15

Ground Methods

Hand sowing—This is the oldest form of direct seeding.

But, as seeding technology improved and areas to be

seeded increased, mechanized ground-sowing equipment

was developed. The simplest of such equipment are handoperated cyclone seeders. These can be very efficient for

seeding small areas.

Hand-cranked seeders have a simple metering device and

have an effective swath of about 16 feet. Daily production

of about 15 acres per individual is common (Derr and

Mann 1971). Organization of crews is straightforward and

flexible; crew members walking about 16 feet apart can

effectively seed sites up to 100 acres in size.

Another hand-sowing technique for small acreages is spot

sowing. It was developed specifically for small landowners

where vehicle operation and other seedbed treatments such

as fire are impractical. A spot is raked, hoed, or kicked free

of vegetation and litter, and 5 to 8 seeds are dropped and

pressed into mineral soil with the foot (Lohrey and Jones

1983). Several hand tools have been developed to facilitate

the task (Burns 1961, Mann 1962).

Spot seeding is better adapted to areas with a ground cover

of hardwood litter than sites with a grass sod. Prepared

sites should be at least 1 foot in diameter and the cleared

material scattered to prevent blowback onto the site. At the

recommended rate of 1,000 spots per acre, 2 to 4 acres can

be seeded per man-day (Campbell 1982a).

Tractor seeding—While hand seeding is possible on small

areas, most ground seeding has been done with row-seeding

machines. Many types of row seeders have been developed.

Some simply drop seeds on previously prepared ground,

but many plow a furrow or disk a narrow strip and meter

out seeds and press them into mineral soil with packing

wheels. Many of these types of seeders are described by

Derr and Mann (1971).

Disk seeders have two main drawbacks. First, they leave

rough beds on which considerable soil is lost by silting.

Second, disking in cool, wet weather fails to control grass

adequately (Derr and Mann 1971).

This seeding equipment typically uses modified agricultural

seed-dispensing devices that are inaccurate on rough forest

sites. A seeder that employs a vacuum system to move

seeds from a hopper and drop them at precise intervals was

developed to improve seed distribution (Richardson 1965).

Aerial Methods

About 75 percent of the total acreage seeded has been from

the air, either with small fixed wing aircraft or helicopters

(Derr and Mann 1971). On operations exceeding 500 acres,

Longleaf pine seed showing epigeal type of germination.

Preparing a spot for hand seeding with the use of a fire rake.
16

aerial seeding is comparable to the cost of most ground

methods of broadcast seeding. It is fast and frequently

the only practical means of sowing inaccessible terrain

or debris-covered areas. When properly calibrated, aerial

seeding is an accurate seeding method, giving complete

coverage regardless of topography, brush, or debris.

Effectiveness of seeding differs little whether applied by

planes or helicopters. Both types require constant checking

of equipment and precision flying for best results. The main

distinction between the two types of aircraft is in the width

of the flight strip; helicopters can seed a strip 100 feet wide,

while small planes are limited to about 65 feet wide. The

primary advantage of helicopters is in the time for loading

seeds; helicopters can land on or near the site, while planes

usually operate from a landing strip miles away.

Accurate aerial seeding requires good ground control, which

is often difficult on rolling topography or where there is a

canopy of hardwoods. Preparation needed in most cases

includes a large-scale map of the area to be seeded, location

of the flagman’s position for each flight line, and marking of

tract boundaries. Detailed discussion of the development of

the field layout for aerial seeding is provided by Derr

and Mann (1971).

Calibrating Seeding Equipment 

Proper calibration—adjustment of the seed release

mechanism to the desired sowing rate—is important in all

operations. For best results the rate of seed flow should

be checked frequently during the seeding operation and

adjusted as necessary.

Thomas C. Croker demonstrating a row seeder which elevates a low

ridge in a plowed furrow and drops seeds that will be pressed into

the soil.

An example map of a site to be aerially seeded showing flight lines and acreages for each. Source: Derr and Mann (1971).
17

Calibration procedures for both ground and aerial

equipment are described in depth by Derr and Mann (1971).

Readers are referred to this publication for specific details.

APPRAISALS

Seed losses begin on the day of seeding and continue

throughout the germination period. Once germination

occurs, attrition of the resulting seedlings begins. A

successful seeding is one where losses are minimized so

that adequate first-year stocking is achieved using the

least amount of seeds. The landowner must have a reliable

estimate of controllable losses, achievable stand density, and

losses from uncontrollable factors such as drought.

Two or three estimates are normally needed during the

establishment period. They are to determine predator

activity, initial stocking, and stocking at the end of the first

year. Direct seeding often has been done without adequate

appraisals, and well-stocked stands have been “discovered”

several years after a cursory examination categorized them

as failures. Even worse, perhaps, are those stands carried on

the record as stocked when they initially failed.

Estimating Predator Activity

Finding the cause of failures of seeding is often a difficult

task. Although birds have been the principal problem in

southern pine seeding, other biological agents will cause

problems in certain areas. Observation stations, where

repeated examinations can be made, are essential for

evaluating predator activity and determining cause(s) of

failures in seeding trials.

An effective observation station consists of an identification

stake and two small, cleared spots containing 25 treated

seeds each located near the stake. An additional screened

spot with at least 10 seeds is usually added to provide an

estimate of field germination (Derr and Mann 1971).

The number of stations needed varies with the acreage of

the seeding and variety of cover conditions. Fifty welldispersed stations are usually adequate for areas of 500 to

1,000 acres in size. More may be needed on larger areas or

where there are wide differences in site or cover conditions.

For small areas, the number can be scaled down, but 15 are

about the minimum needed to achieve meaningful data. 

Frequency of examination of the stations may range from

daily to weekly. The number of seeds destroyed or missing

should be recorded and notes taken on evidence left by

predators. Germinated seeds should be marked with pins

because seedlings are often destroyed with little evidence

of cause.

Observation stations simply provide a quick means of

detecting damage. When damage does occur, further

checking is needed to determine the nature of the losses

and to evaluate the seed treatments. If rodents seem to

be a significant problem and only thiram was used as the

Aerial seeding being used with a fixed-wing plane with seed

distribution controlled by a flagman on the ground.

Observation station with center stake, two spots with 25 treated

seeds each, and a screened spot with 10 seeds to evaluate

germination potential.
18

repellent, the addition of the rodent repellent capsicum into

the formulation may be needed to achieve better seeding

success (Nolte and Barnett 2000).

Identifying Causes of Seed and Seedling Losses

Despite the general effectiveness of repellent coatings,

local losses due to various agents will occur. Checking of

the observation stations at least weekly during the progress

of germination will provide information on the number of

intact seeds and hulled seeds, type of damage to the seed

and seedlings, insect activity, and condition of the repellent

coating. Marking germinated seeds with small pins provides

a method of detecting losses that occur during advanced

stages of germination.

Typically, birds consume seeds either by swallowing them

whole or by shattering the seed coat and removing the

endosperm. So, sometimes no remnants are left for potential

identification of the predator.

However, many predators leave characteristic seed hull

and fragments behind. Some rodents carry seeds a few

yards to a protective cover and leave a neat pile of seed

hulls where they have been feeding. Derr and Mann (1959)

provide descriptive damage to seed remains that are caused

by a number of predators. This information is helpful in

determining local seed predators. 

Loss of established seedlings immediately after germination

is a problem, particularly with fall-sown longleaf pine

seeds. Clipping of the germinated seedlings is the most

frequent type of damage. These seedlings provide green

and succulent vegetation at a time in the year when there is

little green-plant material available to sustain small animals.

Rabbits are a frequent cause of this type of clipping. If

rabbit populations are known to be large, seeding winter

grass near the seeded area may draw rabbits from the seeded

area and limit the extent of the damage.

Although losses from predators typically occur following

seeding operations, climatic conditions or poor seed quality

may also be responsible for some failures. It is important,

then, to install observation stations, or plots, to detect any

unusual damage to seeds and seedlings.

Seedling Inventories

Survival of established seedlings during the first year is

critical for all southern pines. Mortality may vary greatly by

climate, soil type, and cover conditions. Summer droughts

are a frequent problem throughout the South.

Characteristic damage to untreated longleaf seeds by seed predators in central Louisiana. These hull fragments were obtained from caged

predators. (Photo by Brooke Meanley, U.S. Fish and Wildlife Service)
19

To establish causes of early seedling losses, two seedling

inventories are generally advised—one at the beginning

of the summer when germination is completed, the other

at the end of the first growing season when mortality from

summer drought is past. The earlier inventory indicates the

efficiency of the repellents. The second provides an estimate

of overall seeding success. If drought or other adverse

conditions occur during the second or third year, additional

investigations may be important in determining long-term

success of seeding operations. 

Seeding success of broadcast-seeded areas can be

determined by estimating the number of seedlings per acre

and the distribution of these seedlings—these two values are

closely related. Tree percent, the ratio of seedlings to seed,

is often calculated. It should be about 25 percent in early

summer (that is, 1 seedling for 4 seeds); if it is lower than

this something unusual likely occurred.

Stocking, a measure of seedling distribution, is normally

expressed as the percentage of milacre (1/1,000 acre)

sample plots that have one or more seedlings. Land

managers judge success frequently by the stocking percent

after the first growing season. Usually a minimum stocking

percentage of 55 is needed as a judgment of success (Derr

and Mann 1971). Adequate distribution is rarely obtained

with less than 750 seedlings per acre.

Number of seedlings per acre and stocking can be

determined by installation of sampling plots. Circular

milacre plots with a radius of 44.7 inches are ideal for

sampling broadcast seedlings as only a sweep of the plot

radius using a stiff wire or stick from a central point is

needed to establish plot boundaries. Twenty-five is the

minimum number of plots for any seeded area. On large

areas, one plot per acre has been used successfully

(Ezell 2012).

Appraisals of seedling success on broadcast-sown disked

strips, and row- and spot-seeding require modification of the

evaluation techniques. These modifications are described in

detail by Derr and Mann (1971).

STAND PROTECTION AND MANAGEMENT

After the first growing season, mortality from drought

usually is not a major problem and aggressive height growth

begins for most southern pine species. Seedlings usually

outgrow competing vegetation and the primary cause of

mortality is fire. So, protection from wildfire for the first

few years is necessary for most southern pine species.

Use of Prescribed Fire

Unlike most southern pine species, longleaf pine seedlings

do not immediately begin height growth and may remain in

a grass stage for several years unless the stands are properly

managed. While in the grass stage, a number of problems

may contribute to slow initiation of height growth. Unless

site preparation treatments are effective enough to delay

growth of competing vegetation, prescribed fire may be

needed to release longleaf seedlings from overtopping

vegetation and reduce amounts of diseased foliage resulting

from brown-spot needle blight. Longleaf seedlings tolerate

fire during the grass stage, and burning results in increased

availability to light that stimulates seedling growth. Such

use of prescribed fire usually takes place in the second or

third year following seeding.

Seedling infection with brown-spot disease was a significant

problem when direct seeding was being developed. Stands

of old-growth longleaf pines may have occurred many years

earlier, but longleaf seedlings in the grass stage persisted on

many of these sites. These seedlings were typically infected

with brown-spot needle blight and provided a source for the

disease spores to be sustained and to infect newly seeded or

planted longleaf pines.

There was, then, the need for the use of prescribed fire to

burn the disease-infected foliage and present an opportunity

for seedling growth to occur before the infection again

became severe enough to limit growth. However, if a

site does not have longleaf seedlings in the grass stage

Seedling inventories are needed to determine seeding success. H.J.

Derr and B.F. McLemore, above, are filmed making an inventory for

an early 1960s Forest Service movie on direct seeding.
20

and seeded trees begin height growth promptly, brownspot needle disease will not be a major problem. Limited

populations of brown-spot spores occur on land not

previously occupied by longleaf pine.

Even if brown-spot disease is not a problem, use of fire is an

important aspect of longleaf pine management. Prescribed

burning studies were originally installed to evaluate ways to

improve forage production and quality (Barnett and others

2011). But in these studies, Grelen (1975, 1983) established

that burning of longleaf pine stands in May was more

effective than in the dormant winter season for controlling

competing woody vegetation. This schedule of burning

increased survival and growth of longleaf pine seedlings.

These findings that prescribed burning in the spring

increases longleaf performance has become an important

aspect of longleaf pine management.

Precommercial Thinning

One of the problems facing landowners seeding their land

has been overstocking of trees that frequently require

precommercial thinning. Seeding rates were developed in

anticipation of losses of seeds to predators and reduced

germination affected by less than ideal weather conditions.

Also, mortality of seedlings to drought and other adverse

factors are expected during the first year after seeding.

When conditions following seeding are more favorable than

anticipated, numbers of seedlings per acre at the end of the

first year may reach 5,000 or more. 

Maintaining low stand densities can increase diameter

growth, reduce rotations, shorten times to first thinning,

and lesson potential fire mortality. High levels of stocking

may negate these positive effects. Numerous studies

were installed to address the overstocking problem that

sometimes results from direct seeding.

Slash and loblolly pine stands were established by direct

seeding with the intent of obtaining high stocking levels

(Lohrey 1972, 1973b). These studies resulted in over

5,000 seedlings per acre. When the stands were 3 years

old, precommercial thinning—consisting of both selective

Unthinned 11-year-old slash pine with initial stocking of 5,000

stems per acre.

Eleven-year-old slash pine thinned by hand to 750 stems per acre

at age 3 years.

Longleaf pine seedlings following a prescribed burn to reduce

competition and brown-spot infected foliage.
21

hand and mechanical treatments—were installed. When

the stands were 11 years old, results from the thinning

treatments were evaluated.

These and other studies indicate that stands with levels of

stocking of over 2,000 per acre should be precommercially

thinned. To minimize costs, stands should be thinned when

they are 3 or 4 years old. Reducing stocking to 500 and

750 stems per acre will result in optimum diameter growth

without reducing volume production. Thinning by cutting

swaths mechanically was found as effective as selecting

individual stems to be cut. Removing swaths about 10 to

12 feet wide will provide access for protection and stand

management. Thinning can be done with rotary mowers

or rolling drum choppers (Lohrey 1977, Mann and Lohrey

1974), or by chemical treatments (Williams and others

2008). If thinned with mechanical equipment, operations

carried out in late summer are more effective in limiting

sprouting of cut shortleaf, slash, and loblolly pine seedlings

than operations earlier in the year (Campbell 1985b). 

An analysis of the economics of precommercial thinning

shows that it is a financially attractive investment (Fox and

others 1976, Williams and others 2008). Stands in excess

of 2,000 seedlings per acre should receive precommercial

thinning with the goal to reduce the number of seedlings

down to 400 to 800 trees per acre. Thinning can be most

easily done at the age 3 or 4 years, but additional gains in

tree growth can be achieved by treatments applied as late

as age 10.

ADVANTAGES OF DIRECT SEEDING

Direct seeding can be an effective practice for regenerating

the southern pines. On many sites, direct seeding may be

more economical than planting nursery-grown seedlings or

waiting for natural regeneration. Seeding may be the best

choice on sites where access, terrain, or drainage conditions

make planting difficult, although the process requires

considerable technical skill and knowledge.

The choice of seeding depends on the landowner’s goals

and economic situation, as well as the condition of the site

and the capability of the land manager. Advantages of direct

seeding are discussed further.

Lower Initial Cost 

The most notable advantage of direct seeding is lower initial

cost when compared to planting nursery stock (Ezell 2012).

The cost of seeding is usually less than one-half that of the

cost of planting seedlings. The reasons for the reduced costs

are: seeds are usually less expensive than seedlings; labor,

equipment, and facility costs are lower; and site preparation

costs are normally less expensive.

It is important to remember that these cost savings are for

the initial seedling establishment. Because of the lower

costs, however, seeding should be an attractive alternative

for small private landowners.

Flexibility

Another advantage is that direct seeding is easier to

accomplish in remote or inaccessible areas. Although much

of the Coastal Plain in the South is accessible, seeding has

advantages in mountainous areas with rocky soils.

Top: Precommercial thinning of a young loblolly pine stand by

rotary mower mounted on a farm tractor. Bottom: Seeded longleaf

seedlings are beginning height growth on a previously harvested

longleaf pine site.
22

Seeding allows landowners to quickly respond to large

areas affected by wildfires or other natural disasters. Seeds

from storage can be retrieved, treated, and sown within

relatively short periods, whereas, nursery stock may require

a year or more before large quantities of seedlings are

available for planting.

Direct seeding, as does planting, provides an opportunity to

change the species or genetic composition of a forest area.

This is important where forests have been highly degraded.

It presents an option to restore a desired pine species to land

on which high-quality forests previously flourished.

Hard to Plant Species and Low-Quality Sites

Some species, notably longleaf pine, are difficult

to regenerate by planting of bareroot nursery stock.

These problems were the primary reason for the initial

development of direct seeding.

Direct seeding is also a good alternative for regenerating

low-quality sites. Cost of planting such sites may bring

into question the economy of planting such areas. So,

lower initial seeding costs provide a good opportunity for

regenerating sites of low productivity.

Natural Root Systems

The root systems of trees that develop from direct seeding

are considered natural. Planted seedlings may have

distorted roots that end up in an “L-shape” or “J-shape”

if the planting hole is not deep enough. As much as 30

percent of planted shortleaf pine in Arkansas lacked a

taproot compared to only 15 percent of seeded seedlings

(Harrington and others 1986). A distorted root system

may reduce growth, and shallow planting does reduce the

survival of planted stock (Brissette and Barnett 1989).

DISADVANTAGES OF DIRECT SEEDING

The use of direct seeding has declined from its widespread

use in the 1960s and 1970s. There are a number of reasons

for this situation. Disadvantages of seeding are discussed in

the following sections.

Poor Control of Spacing and Stocking

One of the most notable problems with direct seeding is

poor control of tree spacing and stocking (number of trees

per acre). The number of seeds sown is based on assumption

of acceptable rates of survival. If environmental conditions

are ideal, it is possible that too many trees will survive,

resulting in an overstocked situation that will require

precommercial thinning to correct. Maintaining stands

with over 2,000 seedlings per acre will result in reduced

growth and financial return (Williams and others 2008). The

opposite situation is also frequent; establishment may not be

adequate to fully stock the area. This situation is even more

costly to the landowner because additional site preparation

and planting may be needed.

High Mortality on Droughty Soils

Another disadvantage of seeding is high mortality on

droughty soils. During the first month after germination, the

root system is still near the soil surface (Ezell 2012). If the

landowner needs to maximize profits, seeding may result

in poor stocking and be less desirable than planting in areas

with droughty soils.

Seeded stands do, however, provide attractive yields and

profits to landowners. Seeded loblolly pine stands at age

22 yielded only slightly lower yields than adjacent planted

stands (Campbell 1975).

Limited Use of Genetically Improved 

Seed Sources

Seeding normally does not take advantage of the

opportunity to use seeds from genetically improved sources

due to less availability and higher cost. In recent years

genetically improved material of some species is available.

However, these seeds are still generally more expensive

and large quantities are needed, especially for broadcast

Longleaf pine seed with dewinged seed coats—seed coat wing stubs

remain. Genetically improved seeds have seldom been used for

direct seeding.
23

seeding where tree percent (ratio of seeds sown to seedlings

obtained) is significantly less than for planting.

Limited Availability of Large, Open Sites

Seeding is best suited for use on large, open tracts of forest

land. Such open areas are now seldom available. This is one

of the major reasons for the decline in use of direct seeding.

Planting offers better control of spacing and stocking than

seeding on highly productive forest land.

Less Effective Repellent Seed Coating

The removal of the rodent repellent, endrin, from the market

reduced the efficacy of seeding on areas where rodents are

major seed predators. Although no replacement chemical

as effective as endrin has been found, capsicum—in

combination with thiram—has been shown recently to

significantly reduce rodent damage to seeds (Barnett 1998,

Nolte and Barnett 2000). So, these repellents result in direct

seeding remaining a viable option for reforestation.

Limited Availability of Personnel

An additional problem limiting successful application of

seeding is the availability of specialists with a high degree

of technical skill, knowledge, and experience with seeding

(Williston and others 1998).

ROLE OF SEEDING IN THE 

REFORESTATION OF THE SOUTH

In the late 1940s and early 1950s, foresters in the South

faced a huge reforestation problem—millions of acres of

forest land clearcut in the early 1900s remained desolate

and non-productive. Much of this land was previously

occupied by mature stands of longleaf pines; however, the

harvest was so complete that no seed source remained to

allow for natural reproduction. Planting of longleaf pine

was unreliable at that time.

The potential of direct seeding longleaf pine was especially

appealing, and seeding studies began in the early 1950s.

These evaluations determined that failures of seeding were

primarily caused by bird and rodent predation. Key to the

success of seeding was the development of repellents to

limit predation. Finding effective repellents led to the

need for supporting research programs that provided

necessary seed production capacity, methods of

eliminating competing undesired and low-quality

hardwoods, and clarification of site-preparation needs.

These supporting research programs were critical for

the implementation of large-scale seeding operations (Mann

1968, 1969; Mann and Burkhalter 1961). 

The largest application of seeding remained in the West

Gulf Coast region due to the huge areas of open land

needing to be reforested and seeding was found to be well

suited to such areas. However, seeding technology was

quickly adapted and applied to meet reforestation needs

throughout the United States and other locations across the

World where coniferous species are grown (Mann 1965,

Rietveld and Heidmann 1976, Vietmeyer 1981, Walters and

Whitesell 1971).

Extent of Seeding Southern Pines

Although direct seeding was initially developed for

reforesting longleaf pine, seeding technology was rapidly

adapted to other southern pine species. Because of the

rapidity in which reforestation could be achieved, the use of

seeding quickly spread across the South.

Direct seeding was never meant to replace planting as a

regeneration tool, but it was used over a 25-year period to

aggressively reforest over 1,725,000 acres of forest land in

the South (Campbell 1982b). Its greatest use has been in

regenerating vast acreages of cutover forests that remained

without a seed source needed for natural regeneration.

Forest industry and public land managers quickly accepted

and applied the technology to restore these deforested lands

to productive use (Mann 1968, Mann and Burkhalter 1961).

Seeding was largely applied to reforest open areas of

clearcut forests; however, many landowners began to see it

as an inexpensive tool for reforesting small tracts (Campbell

1981b, Mann and Burns 1965). Currently, direct seeding

is seen as a viable option for restoring sites of small land

ownerships, and guidelines for the technology for this use

Growth of direct seeding in Louisiana as seeding technology

developed. The chart was developed in 1960 to illustrate the

expansion of direct seeding within Louisiana.
24

are readily available (Duryea 1992, Ezell 2012, Gwaze and

others 2005, Williston and others 1998).

Evaluation of Seeded Stands

The growth of direct seeded pines has been evaluated in

a number of studies. At age 9, planted loblolly and slash

pines were taller than seeded pines (Lohrey 1973a). For

both species, the height difference was equivalent to about

1 year’s growth. When the 1-year age difference between

planted and seeded trees is considered, most of the seeding

treatments compare favorably with planting.

Evaluations of the site preparation treatments showed that

mechanical site-preparation treatments for direct seeding

were generally not effective in boosting growth (Campbell

1981c). The treatments included planting, broadcast

and swath seeding on a burned rough and on disked and

mounded strips, and furrow seeding. Results showed that

disking and furrowing enhanced first-year survival in a dry

year, and mounding promoted growth on excessively wet

sites. The early positive response to mechanical treatments

seemed to result primarily from reduction in vegetative

competition.

When growth of the Lohrey (1973a) study was measured

at age 20 years (Campbell 1985a), planted loblolly pine

yielded volumes that were not significantly higher than

volumes on 3 of the 6 direct-seeding treatments. However,

planted trees were fewer in number, larger in diameter, and

more uniformly spaced than seeded trees. Slash

pine volumes were not significantly different by

regeneration method. 

In an effort to evaluate if growth projections of slash pine

planted and seeded stands differed markedly, Lohrey (1984)

developed equations for estimating total green or dry weight

of stems or crowns and the ratio of merchantable stem to

total stem weight. There were significant differences based

on the size of trees that reflected development in response to

variable tree spacing and 1-year difference in initial height.

In a more recent study, Haywood and Barnett (1994) found

that 15 years after planting bareroot and container seedlings

and seeding loblolly and slash pines in a comparative study

that growth of seeded seedlings was slightly less than that

of planted stock. This primarily reflects the age advantage

of planted seedlings. The results do show that direct seeding

can be a viable regeneration alternative, especially when

regeneration costs are a limiting factor.

Lohrey (1987) developed site index curves for direct-seeded

slash pine in Louisiana. The models that resulted were close

to the existing ones for natural regenerated slash pine. In an

expansion of this effort, site index curves for direct-seeded

loblolly and longleaf pines were prepared (Cao and others

1997). These site index models provide short-term height

projections for direct-seeded pines of these species in the

mid-South.

CURRENT APPLICATION OF DIRECT 

SEEDING TECHNOLOGY

Today, use of direct seeding is limited. Traditional forest

regeneration by natural seeding or planting of genetically

improved nursery stock is the prevalent means of

reforestation on highly productive sites.

Where Should Direct Seeding Be Used?

Basically, any site that can be planted with seedlings can

be direct seeded. The primary exceptions are excessively

droughty areas previously discussed. However, there

are four areas where seeding has the greatest current

application: (1) large areas requiring reforestation resulting

from wildfires or other natural disasters, (2) remote or

inaccessible areas, (3) low-productive sites where growth

of trees would not make the cost of planting operations

economically feasible, and (4) any area where a minimal

investment is absolutely essential (Ezell 2012). The

last category is important because many small private

landowners cannot afford the cost of intensive site

Site index curves, base age 25 years, for slash pine stands preparation and planting. It is better to direct seed these

established by direct seeding. Source: Lohrey (1987)
25

areas rather than to allow them to grow up with undesirable

species and brush. 

What Species Are Best Suited 

For Direct Seeding?

Problems with the regeneration of longleaf pine were a

primary reason for the development of direct seeding, and

seeding remains an option for its regeneration. However,

the development of container planting of longleaf is now

a reliable and preferred method for its reforestation (Barnett

and McGilvray 1997). Container seedlings are costly,

but cost-share programs will lower the expense to the

landowner.

Species selection will be affected by goals of ownership,

but putting a species on the sites where it grows best and

with less danger of loss results in the most successful

direct seeding. Also, seed availability and treatments

must be considered.

Sand pine (P. clausa) is a species ideally suited for direct

seeding. It occurs on sandy, infertile soils in the Florida

sandhills where low tree quality and productivity require

limited reforestation investments. McReynolds and Burns

(1973) reported that direct seeding was a better alternative

to planting and natural regeneration for this species. 

In a comparison of sand, slash, and longleaf pine—planted

and seeded—Outcalt (1985) found that nursery seedlings

grew faster, but by age 8 years, growth of sand pine was

similar on both planted and seeded areas. Planted slash

and longleaf trees were still significantly larger than

direct seeded trees due to the advantage gained initially.

Comparisons among species found that on these sandhill

sites, sand pine had the best rate of growth and was the only

species successfully established by direct seeding.

To minimize costs and control spacing and stocking of

seeded sand pine, Outcalt (1990) evaluated a tractor-drawn

scarifier-seeder for regeneration of sand pine. Called the

Bracke® seeder, this device distributes seeds along small,

machine-created ridges which were about 3 inches high.

This equipment has been operationally used in the sand-pine

scrub ecosystem and results in successful seeded stands that

are cost appropriate for the slow growth and productivity

of these sites.

Shortleaf pine is another species that grows on soils of low

productivity—these are mountainous and rocky, but well

suited for direct seeding. Gwaze and others (2005) and

Seidel and Rogers (1965) built the case for restoration of

shortleaf pine which once occupied 6.6 million acres, but

now is found on <400,000 acres. Much of this land is in

small land ownerships and suited for relatively inexpensive

Seeding with cyclone seeders is a viable regeneration option for land managers who have small tracts to reforest. Longleaf pine seeds are

being distributed by men in this photo.
26

direct seeding. Gwaze and others (2005) also provide

guidelines for direct seeding shortleaf pine in Missouri. The

authors suggest that direct seeding is a potentially viable

and cost-effective method of restoring shortleaf pine.

With exception of large areas where extensive forests were

destroyed by wildfire or other natural disasters, selection

of species suited for direct seeding are those that typically

grow on infertile soils or inaccessible sites and that may be

economically reforested by direct seeding.

What are Weather Constraints?

Many have noted that arid soils or periods of low rainfall

may reduce the success of direct seeding. During the late

1950s and early 1960s when seeding trials were conducted

and operational seeding techniques were largely applied, the

South was in a period of rainfall that favored direct seeding.

In more recent years, rainfall has fallen below the averages

of the 1950s and 1960s.

To evaluate current rainfall patterns to that of the period

of successful direct seeding, weather data was analyzed

by the Palmer Drought Severity Index (PDSI). The PDSI

is the most commonly used drought index in the United

States and was developed to measure intensity, duration,

and spatial extent of drought. PDSI values are derived

from measurements of precipitation, air temperature,

and local soil moisture, along with prior values of these

measures. Values range from -6.0 (extreme drought) to +6.0

(extreme wet conditions), and have been standardized to

facilitate comparisons from region to region (Palmer 1965,

Thornthwaite 1948).

Based on the average monthly PDSI for the fall and winter

months (October through March), the period from late

1956 through early 1962 was less droughty than for the

30-year period from late 1932 through early 1962, with

the exception of February that was similarly droughty in

both periods (table 2). The relatively moist era from fall

1956 through winter 1962 was when direct seeding was

most widely used in central Louisiana. In addition, the

period between late 1956 through early 1962 was also less

droughty than from late 2006 through early 2012. In fact,

the 6-year period from late 2007 through early 2012 was

drier than the 30-year period from late 1982 through early

2012. This suggests that direct seeding might not have been

as successful in recent years as in the past because of the

sensitivity of germinating pine seeds to droughty conditions.

These data indicate that land managers and owners thinking

of using direct seeding as a regeneration tool should

consider the severity of soil moisture regime for the area

planned for seeding. PDSI data are readily available from

the NOAA National Climate Data Center Web site www.

ncdc.noaa.gov/oa/climate/research/prelim/drought/palmer.

html.

What Does Site Preparation 

Need To Accomplish?

Site preparation for direct seeding should accomplish

two purposes (Ezell 2012). First, mineral soil must be

exposed. This can be done by burning or disking the area

if it is an old field, or the area can be disked and burned

if this is the better treatment to achieve the needed result.

Second, some degree of competition control is desirable.

The site treatments must result in enough competition

control to get a stand established and begin height growth.

If economically feasible, an application of herbicides may

be beneficial in areas where competing vegetation is well

established and hard to control. 

What Seed Treatments Are Needed?

Seed availability must be considered. Since most

landowners do not have the capability to collect and process

seeds, they routinely purchase from commercial seed

Sand pine growing on infertile sandhill sites in northwest Florida.

This sand pine scrub ecosystem is common on these deep,

sandy sites.
27

dealers. Seeds should have viability of at least 85 percent

and a minimum of 95 percent sound seeds.

Two types of seed treatments may be required for successful

direct seeding. The first depends on the amount of seed

dormancy that may require stratification or prechilling to

assure prompt germination after seeding. Most forest seed

companies have the knowledge and resources to provide

appropriate seed stratification treatments.

The second seed treatment is to protect the seeds from

bird and rodent predation after seeding and through the

germination process. Thiram is the most common bird

repellent. It also provides a limited amount of rodent

repellency. However, if the area to be seeded is relatively

small, rodent predation can be a serious problem because

animals can be drawn from surrounding areas. The best

replacement for endrin is capsicum, which in combination

with thiram, provides good seed protection. Effective rates

for this repellent coating per pound of seed are: 76 ml

thiram (Gustafson 42-S®), 3 ml latex, and 1 ml capsicum

(concentration of 500,000 Soville Units).

Most forest seed companies can provide the seeds of the

species needed along with necessary stratification and

repellent treatments.

When Should Seeds Be Sown?

Longleaf and sand pine seeds are typically sown in the fall

when soil moisture is fully recharged. Seeds of both species

germinate promptly without stratification. Seed predation is

normally low in the fall as rodent populations increase later

in the fall and winter. 

Species such as loblolly, shortleaf, and slash pine have more

dormant seeds and are stratified before sowing in the early

spring, about when the first redbud and red maple blooms

appear. Stratified seeds sown in mid-February usually

complete germination by mid-April.

Table 2—Average Palmer Drought Severity Index values from fall 1956 through winter 

1962, fall 2006 through winter 2012, and the preceding 30-year averages for both periods 

in central Louisiana (positive numbers mean wetter and negative numbers mean drier 

than normal)a

Month

Fall 1956

through

winter 1962

30-year

average

for

fall 1932–

winter 1962

Fall 2006

through

winter 2012

30-year 

average

for

fall 1982–

winter 2012

October 0.60 -1.93 -2.58 2.14

November 0.78 -1.54 -3.76 2.77

December 1.43 -1.91 -2.80 1.13

January 0.80 -1.00 -3.09 0.67

February -1.46 -1.21 -3.54 0.72

March 2.39 -0.15 -3.84 -0.66

a

Average Palmer Drought Severity Index values for the 6-month periods were calculated by James D. 

 Haywood, U.S. Department of Agriculture Forest Service, Southern Research Station, Pineville, LA 71360.

Disking an area with grass sod allows seeds to become in contact

with mineral soil and reduces vegetative competition after

germination.
28

How Are Seeds Distributed?

There are many methods of sowing seeds. Large tracts of

land (over 500 acres) are often broadcast sown by airplanes

or helicopters. This method is fast and provides accurate

and complete coverage. Another method for large tracts

of land uses row-seeding machines, which plow or disk a

narrow furrow or strip, meter out specific amounts of seeds,

and pack the seed into the soil.

Small tracts of land can be sown with hand-sowing or spotsowing techniques. Hand-cranked cyclone seeders with

metering devices are the most efficient. One person can sow

15 acres per day. Seeds can also be sown on hand-raked

spots, approximately 2 feet in diameter and spaced about 8

by 8 feet (Duryea 1992). Five to 8 seeds should be pressed

into the soil at each spot and 2 to 4 acres can be sown in 1

day using this method.

How Is Direct Seeding Success Determined?

Since many variables affect the success of direct seeding,

careful inventories are needed to evaluate the results. At

least one inventory is essential at the end of the growing

season following seeding.

Sample plots should be of milacre (1/1000 of an acre) size

for broadcast-seeded areas. These are circular plots with a

radius 3 feet 8.7 inches. The plots can be measured using

a stiff wire or stick of that length for scanning the plot area

from a central point. The number of seedlings found in each

plot is recorded.

Twenty-five is the minimum number of plots for any seeded

area (Ezell 2012). On large areas, one plot per acre may be

sufficient. To obtain the number of seedlings per acre, the

following procedure is used: (1) divide the total number of

counted seedlings on all plots by the number of plots, and

(2) multiply the average number of seedlings by 1,000. To

determine the stocking percentage, multiply the number of

plots with 1 or more seedlings by 100.

A successful seeding is one that results in over 1,000

seedlings per acre with 55 percent stocking. If the inventory

indicates fewer than 1,000 seedlings per acre or <55 percent

stocking, make another inventory at the end of the second

growing season before a decision is made on whether to

reseed or plant. Areas with more than 2,000 seedlings

per acre at the end of the first growing season should

be resampled at the end of the third year to determine if

precommercial thinning is needed.

Row seeding and spot seeding will require a different

sampling approach for best accuracy, but the milacre

method may be used with confidence if enough samples are

taken (Mann and Derr 1964). 

CONCLUSIONS

Millions of acres of cutover pine forests resulting from

the “golden-age of lumbering” early in the 20th century

provided a challenge to foresters. Forests in the West Gulf

region were particularly decimated due to the use of steampowered logging equipment as aggressive harvesting moved

into this region. Wakeley (1930) estimated that based on

the then rate of planting, it would take 900 or 1,000 years

to reforest the denuded forest land that occurred throughout

the Nation. 

With this understanding of the need for reforestation

capability, the Southern Forest Experiment Station

established a research center at Alexandria, LA in 1946,

with reforestation research as a priority. At the time, the

capacity of tree nurseries to provide needed amounts of

planting stock was limited. The idea, then, of direct

seeding large acreages quickly was intriguing and became

a research priority.

Early studies determined that a major limitation in

successful seeding was bird and rodent predation. With

collaboration of the U.S. Fish and Wildlife Service,

scientists found effective repellents, and direct seeding

became a possible reforestation option. Anthraquinone

and thiram were found to effectively repel birds from

eating pine seed and were environmentally safe chemicals.

Endrin did a good job of limiting losses due to rodents,

Pilot loading treated pine seeds into a seed hopper mounted on a

helicopter for broadcast seeding.
29

but after numerous years of use was withdrawn from the

market due to environmental concerns. However, use of

the thiram-endrin combination resulted in successful direct

seeding and was used across the South and beyond. More

recently, endrin was replaced with capsicum, which lacks

the level of protection of endrin, but in combination with

thiram does provide a good level of seed protection.

The practice of direct seeding proved applicable

throughout the South. The dramatic development and

use of direct seeding caused the need for expanding

supporting research in seed science, in control of

undesired and low-quality hardwoods on many pine

sites, and in determination of site preparation needed for

successful seeding.

The development of direct seeding and the related research

programs at Alexandria gained national and international

recognition. In 1961, the Alexandria Research Center was

awarded the U.S. Department of Agriculture Superior

Service Award for these research accomplishments.

By the early 1970s, direct seeding had been highly

effective in restoring southern pines to almost 2 million

acres of cutover forest land throughout the South. As

much of the open forest land was reforested by planting

and seeding, the need for direct seeding declined. Use of

seeding is most efficient on large, open areas. Loss of the

availability of endrin, the effective rodent repellent, further

limited the application of seeding. Too, the lack

of stocking control with seeding often resulted in

excessively stocked stands that required precommercial

thinning. With the capacity of forest tree nurseries greatly

increasing the use of genetically improved seeds, planting

became the most attractive option on highly productive

forest land. For these reasons, use of direct seeding

continued to decline.

Currently, the use of direct seeding is primarily limited

to restoration of large forested areas destroyed by

wildfires or other natural disasters and to areas of low soil

productivity where it is not economically feasible to plant

more expensive nursery stock. Seeding is also a viable

alternative for land ownerships where small tracts need

reforestation. The economics of seeding on such areas

make direct seeding a good option.

For seeding to be a practical alternative technique, even

on favorable sites, a high degree of technical skill and

knowledge is needed. The key to success lies in obtaining

the advice and assistance of an experienced specialist.

Unfortunately, the availability of such specialists is now

Direct seeded longleaf pine seedlings that have begun height growth. Direct seeding was used to effectively reforest hundreds of thousands

of acres with longleaf pine.
30

ACKNOWLEDGMENTS

The scientists who worked to develop direct seeding technology were dedicated and determined. Their contributions

were recognized through the numerous publications that chronicled their research. This document is dedicated to those

technical support personnel who spent their careers supporting the research efforts and who contributed significantly—

without recognition—to the success of the programs.

limited, and for this reason use of direct seeding may

continue to decline.

Before direct seeding their land, land managers and

owners should consider the severity of the drought index

for the area planned for seeding. If soils are droughty,

the success of direct seeding operations may be

significantly reduced.

Regardless of future use, direct seeding was developed

and applied to meet a specific need—reforestation of

massive areas of cutover forest land. Seeding technology

was developed over a few years and was put in use

immediately. This was a remarkable accomplishment

and resulted from intensive collaboration among Forest

Service research scientists, U.S. Fish and Wildlife Service,

forest industry operational managers, and university

extension specialists. Direct seeding met a significant need

at the time—millions of acres of devastated forest land

were put into production. 

W.F. William “Bill” Mann, Jr. (left), leader of the research program,

is shown receiving the U.S. Department of Agriculture Superior

Service Award from Carl Ostrum (right) of the Forest Service’s

Washington Office. Harold D. Burkhalter (center) represents the

Louisiana Forestry Association, a major supporter of the research

program.
31

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Barnett, J.P. 2014. Direct seeding southern pines: history and status of a

technique developed for restoring cutover forests. Gen. Tech. Rep. SRS-187. 

Asheville, NC: U.S. Department of Agriculture Forest Service, Southern

Research Station. 35 p.

Early in the 20th century the deforestation resulting from the “golden-age of

lumbering” left millions of acres of forest land in the need for reforestation.

The challenge was so extreme that foresters of the early 1930s estimated that it

would take 900 to 1,000 years at the then rate of planting to reforest the denuded

forest land that occurred throughout the Nation. Forests of the West Gulf region

were especially decimated due to the development and use of steam-powered

logging equipment that left little capability for natural regeneration. Faced with

this need, scientists of the Southern Forest Experiment Station began an effort to

develop direct seeding with the hope of quickly seeding large open areas of the

South with southern pines. Protecting seeds from bird and rodent predation was

key to successful direct seeding, and in the mid-1950s certain chemicals were

found that made seeding an effective tool. Additional components of a successful

direct seeding operation were increasing the availability of quality pine seeds,

finding methods of eliminating hardwood brush competition, and developing

site preparation treatments that favored seeding. This supporting research was

essential for the resulting successful restoration of millions of acres of southern

pine forests. Today, direct seeding is infrequently used, primarily due to lack of

large, open areas needing reforestation. But back then, seeding met a significant

need, and millions of acres of forest land were put back into production.

Keywords: Chemical hardwood control, competition control, precommercial

thinning, reforestation, seed repellents, seed research, site preparation, southern

pines, stand stocking.

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