United States Department of Agriculture

Iowa Native Prairie Planting Guide

Native Prairie

establishing & managing native plantings

USDA is an equal opportunity provider, employer and lender.

This guide provides directions for establishing and 

managing native prairie plantings, including postplanting weed control, prescribed burning, mowing 

and haying.

Natural Resources Conservation Service, Des Moines, Iowa, September 2018

A native planting mowed during the first year.

Prairie grasses and wildflowers grow slowly. Weeds grow 

much faster in the first couple of years. In the first year, 

prairie plants work to establish their root systems and 

therefore grow very little on the surface. In fact, some 

forbs take several years to appear. You may see some of 

the quick establishers in the first year, such as Black-eyed 

Susan, partridge pea and sideoats grama. Have patience 

and give it time. 

The following are key management tips for the first year:

» Scout your field during the establishment period for 

weed growth and pressure. Weeds can double their 

height in a week.

» Expect to mow weeds 2 to 3 times from June 

through July. The actual mowing frequency will 

depend on rainfall, weed density, height, and weed 

species present.

» Mowing before weeds get “Knee High” is a good 

rule of thumb. Allow as much light as possible to the 

seedlings.

» Mow weeds down to approximately 6-8 inches. The 

first mowing after seeding, if done timely, can be 

mowed at 3-4 inches.

» Do not spray any broadleaf chemicals on establishing 

stands. Not only will broadleaf chemicals kill forbs, 

but they can also kill or damage seedling grasses.

» Dormant/early plantings will require mowing early 

in the season, and an additional mowing trip may be 

needed. 

» Typically, don’t mow after Aug. 1.

» Evaluate stand in early fall.

First Year (Mow Often)
Establishing & Managing Native Plantings

Second Year (Early Bloomers) Marestail grows in a second year native planting.

Prescribed burning on a southern Iowa native planting.

» Plan to mow once (6-8”), then evaluate the native 

planting to see if additional mowing will be needed. 

» Spot mowing may be needed in areas where weed 

pressure is still prevalent. Giant Ragweed can be very 

persistent. Musk thistles may still be prevalent, but 

will be out-competed by the prairie long-term.

» Do not use herbicides for spot spraying until Year 3 

of the native planting.

» Marestail (a winter annual shown at right) will often 

show up in the second year. It looks worse than it is, 

but its growth pattern still allows light through the 

canopy. Marestail will naturally decline as the prairie 

establishes.

» Mow Canada thistle patches at bud stage (late June to 

early July). The prairie will often out-compete thistles 

with timely mowing.

» By mid-July, an inspection of a new establishment 

should indicate a diverse mixture of natives, though 

the seeding will still have a weedy appearance. Forbs 

will start to bloom.

» A prairie stand is “established” when there is an 

average of 1 plant/ft2. This may take until Year 3.

» Evaluate your native planting annually from the third 

year on.

» Spot treat perennial weeds or invasives (i.e. Canada 

thistle, introduced grasses) as needed. 

» Mowing and haying (July 15-Aug. 31) are great 

tools for reducing the tall grass component and will 

invigorate forbs. (Follow program guidelines.)

» Prescribed Burning is a useful tool that is part 

of the tall grass prairie ecosystem. Burning helps 

control unwanted trees, remove duff, and stimulate 

native grasses and forbs. Refer to the Prescribed Burn 

Schedule on the next page for influence of fire on the 

plant community. 

• Consider burning every 3–5 years to promote 

a healthy prairie. Additional burning may be 

warranted for certain conditions. 

• Delaying the first prairie burn until after the third 

growing season can help with forb establishment.

• Burning can stimulate sometimes unwanted 

invasives, like sweet clover.

• When conducting burns on acres enrolled in 

conservation programs, refer to program policy.

• Utilize the Prescribed Burning Iowa Job Sheet 

when completing prescribed burn plans. 

Third Year & Beyond
Natural Resources Conservation Service

Prescribed Burn Schedule

Dates Forbs

Warm Season 

Grasses

Introduced 

Cool Season 

Grasses Trees

11/15-4/1

*4/1-4/15

4/15-5/15

7/15- 8/31

Positive Neutral Negative

*These dates vary, but it’s a time when the introduced grasses are actively growing and fire will set them back. The forbs are just 

starting, so the fire will have minimal impact.

Affect of Burn Timing on Plant Community

» In the establishment phase, limit competition from 

weeds to prevent a stand failure. Too many of the 

wrong kinds of weeds in your native plantings may 

block the sunlight and smother out establishing 

natives.

» It is okay to have some non-noxious weeds in your 

native planting. Annual weeds provide many benefits 

for wildlife, including habitat for insects, food for 

growing chicks, protection from predators and 

weather, and an overall food source for managing 

wildlife.

» Do not mow after weeds are 4-6 feet high. At that 

point you are better off not to mow. Doing so will put 

a mat of material on the new emerging seedlings. It 

may look better to the neighbors, but it will have a 

negative impact to the seeding.

» Spot mowing on established stands is preferred over 

chemical use for weed control. Using chemicals to 

spot treat noxious weeds will also kill native forbs. 

Wait until Year 3 to use herbicides for spot spraying, 

after the prairie is established.

» Mowing CRP acres is allowed until the stand is 

considered established. Once the stand is considered 

established, visit your USDA-Farm Service Agency 

office before conducting any weed control activities, 

such as mowing or spraying. 

» Prescribed burns need to be planned and executed 

in a careful and strategic manner using a prescribed 

burn plan. A burn plan is a site specific technical 

guide that details:

• firebreak locations (critical component), 

• an ignition plan, 

• equipment needed, 

• personnel needed, 

• potential fire escape areas, 

• potential damage risks (i.e. wood fence posts, 

plastic culverts or intakes) 

• May 15 to Aug. 1 is the primary nesting season. 

Conservation Reserve Program (CRP) rules do 

not allow prescribed burning or managed haying 

during this time period.

» Eastern red cedar trees can be controlled with 

prescribed fire. Green foliage must be totally burned to 

kill it.

» Varying the disturbance and the timing can be 

beneficial overall to the prairie and plant community.

Other Considerations
Establishing & Managing Native Plantings

Introduced Grass Control

It is much easier to kill introduced grasses before you 

seed a native mix than eradicating them after the seeding 

is planted.

Option 1 – Prescribed Burn

» Complete in May to setback the actively growing 

introduced cool season grasses. 

• Benefits: Warm season native grasses will thrive, 

while the introduced grasses will be stunted. 

• Negatives: Native forb population can also be 

reduced, since they are cool season. Provides only 

a short-term benefit.

Option 2 – Kurtz Method

» Mow an established native stand (after 3 growing 

seasons) in mid-October. Established forbs mowed 

at this point will not grow back that fall. Native warm 

season grasses are dormant.

» Spray glyphosate at the perennial rate (2 quarts when 

active ingredient is 41%).

• Benefits: Very effective at killing introduced 

grasses such as smooth brome grass, bluegrass, 

orchard, etc. This method is not effective at killing 

reed canary grass, which would need time to get 

fresh regrowth. 

• Negatives: There is a risk of killing some native 

forbs and native cool season grasses.

Option 3 – Prescribed Burn/Grass Herbicide

» Complete a dormant or early spring prescribed burn.

» When the cool season grasses green back up (4”-5” of 

height), spray a grass-only herbicide (i.e. Clethodim)

to stunt/kill the introduced grasses.

• Benefits: Much better at stunting/killing the 

introduced grasses than a fire burn alone.

• Negatives: Risk of stunting/killing the cool season 

native grasses (Canada Wild rye, June grass, etc.)

Canada Thistle

Canada Thistle Control

Before seeding

» Use 3 quarts of glyphosate when active ingredient is 

41%.

» Glyphosate will have no residual affect to a new 

seeding.

» Follow label for specific rates, spray adjuvants, etc. 

After seeding

• Option 1 - Mowing: Mow at bud stage (late June 

to early July) for greatest affect. Timely mowing 

will often be enough to give the prairie the edge to 

out compete.

• Option 2 – Spraying: Rely on mowing in the first 3 

growing seasons, if possible. 

* (Best) - In the third growing season, mow the 

patches where the prairie is struggling to outcompete it at bud stage (late June – early July). 

Then, come back in the fall and spot spray with 

aminopyralid (i.e. Milestone) on those areas.

Aminopyralid (i.e. Milestone) Details

» Long residual (2+ years). The residual makes it more 

effective because the rhizomes of Canada thistles are not 

all active at the same time, making it difficult to kill. 

» It is more selective than most broadleaf herbicides; some 

forbs are not susceptible to it, especially if they are well 

established. 

» Follow label for specific rates, spray adjuvants, etc.