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| ## PERENNIAL RYEGRASS {#perennial-ryegrass .Title-Header}             |
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| *Lolium perenne* L. ssp. *perenne*                                    |
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| Plant Symbol = LOPEP                                                  |
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Contributed by: USDA NRCS Idaho State Office

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height="3.8131944444444446in"}

Britton & Brown. 1913. Flora of the North States and Canada

##### Alternate Names {#alternate-names .Header-3}

None

##### Uses {#uses .Header-3}

A few farmers and ranchers are beginning to plant perennial ryegrass,
*Lolium perenne* ssp*. perenne*, on irrigated pasture in the
Intermountain West. This paper is intended to provide some technical
guidance in the establishment and management of this species for the
Intermountain West.

Perennial ryegrass is a valuable forage and soil stabilization plant.
This species is one of the predominant forage grasses in Europe. It has
been used in the United States for forage and turfgrass applications
since the late 1700s. Generally the tetraploid varieties are used for
forage and diploid varieties are used for turfgrass (lawn) and
conservation plantings. Users should double check the intended use of
available releases before buying seed to ensure they are getting the
type desired. Italian ryegrass, the annual *L. perenne* ssp.
*multiflorum*, is primarily used for quick cover in erosion control
plantings.

Why plant perennial ryegrass? There are several very good reasons to
consider perennial ryegrass when planning an irrigated pasture planting.
Perennial ryegrass establishes easier and more quickly than most of our
proven long-lived pasture grass varieties. Under ideal conditions,
perennial ryegrass is ready to graze within 60 days of planting. When
managed correctly, it can be very productive. Perennial ryegrass can
also be inter-seeded in existing weak stands of grass with fairly good
results (avoid inter-seeding healthy, productive stands). It can be
broadcast seeded followed by harrowing, packing or livestock trampling
with fairly good establishment results. Perennial ryegrass is very
nutritious having similar or higher energy and protein levels than most
proven pasture grass alternatives. This is a very important
consideration when grass fattening beef cattle or for maintaining high
milk production with dairy cows. It is also considered to be a very
palatable feed. Preliminary forage quality results from a Montana study
indicated good potential for high production of both protein and total
digestible nutrients (TDN) per acre, depending on level of inputs and
harvest management.

Because we do not have long term information on the survivability of
perennial ryegrasses, we recommend the following to farmers and ranchers
interested in planting perennial ryegrass.

-   Use perennial ryegrass only in pastures that will be intensively
    managed.

-   Plant only in areas with a good supply of irrigation water.

-   Provide high levels of fertilizer with frequent applications.
    Perennial ryegrass production increases with split applications of
    nitrogen. It is recommended that 45 pounds per acre of nitrogen
    follow each grazing cycle. If only one application is economically
    feasible, then apply 150 pounds of nitrogen per acre in the spring.

-   When planted with white clover, apply fertilizer in two
    applications, early spring and early autumn. When planted without
    clover, 3- 5 applications may be necessary.

-   Use varieties bred in Holland to provide earlier dormancy and better
    winter hardiness.

-   In cold winter areas, perennial ryegrass has excellent first season
    yields and quality; however, plants may be subject to winter-kill
    and may require reseeding and should generally be viewed as annual
    or short-lived forage crops that may require renovation each year.

##### Status {#status .Header-3}

Consult the PLANTS Web site and your State Department of Natural
Resources for this plant's current status (e.g. threatened or endangered
species, state noxious status, and wetland indicator values).

#####  {#section .Header-3}

##### Description {#description .Header-3}

*General*: Perennial ryegrass grows from 1 to 2 feet tall with a bunchy
form. It has medium longevity in mild climates. In northern
Intermountain and Rocky Mountain states it tends to be short-lived,
often no more than one growing season. Some turfgrass varieties are
longer lived. There are numerous long, narrow, stiff leaves near the
base of the plant where most of the forage is concentrated. The under
surfaces of leaves are bright, glossy, and smooth. Inflorescence stems
are nearly naked. Seedheads are spikes with spikelets growing edgewise
(at right angles) to the reproductive stem. Perennial ryegrass seeds do
not have awns (bristles), whereas annual ryegrass seeds have awns. Other
morphological characters of the two species are similar. There are
approximately 247,000 seeds per pound.

Annual and Italian ryegrass are similar to perennial ryegrass except
they are annual or biennial, depending on climate and/or length of
growing season. Italian ryegrass may grow a little taller than perennial
ryegrass: from 2 to 3 feet tall. The seed of this sub-species have awns.

*Distribution*: For current distribution, consult the Plant Profile page
for this species on the PLANTS Web site.

##### Adaptation {#adaptation .Header-3}

Perennial ryegrass has a wide range of adaptability to soils, but
thrives best on dark rich soils. It will withstand fairly wet soils with
reasonably good surface drainage. It will not tolerate standing water
for extended periods of time. It grows on soils that have a pH between 5
and 8 with best yields on soils with pH between 6 (slightly acidic) to 7
(neutral).

Perennial ryegrass should be restricted to regions having mild climates
with moderate temperature and higher moisture or irrigated regions of
the Intermountain and Rocky Mountain West. It does not withstand hot,
dry weather or severe winters. To produce high yields, perennial
ryegrass requires 30 to 50 inches of rainfall or equivalent supplemental
full irrigation annually.

##### Establishment {#establishment .Header-3}

A firm, weed-free seedbed gives the best results. Spring seedings should
occur in March to early May. Perennial ryegrass may also be seeded in
mid-August to early September under irrigated conditions. Timing for
fall seedings should ensure that at least 6 weeks are allowed for
establishment prior to killing frosts. Seeding rates will vary with
local conditions and purpose of planting. Generally, a rate of 15 pounds
per acre is used if perennial ryegrass is seeded alone. Double this rate
if seed is broadcast planted. Perennial ryegrass is also recommended for
grass-legume mixtures, but due to a strong animal preference toward
perennial ryegrass over other pasture grasses, it should not be planted
with other grasses for grazing. Reduce the full rate to the percentage
of mixture desired when planting with legumes. Because perennial
ryegrass has very strong seedling vigor, it should be planted at 7 to 8
pounds per acre in alternate row plantings with alfalfa and other
legumes. When planting in the same row, do not exceed 4 pounds per acre
of perennial ryegrass in the seed mixture with alfalfa and other
legumes.

When planting with a drill, the ideal seeding depth is ¼ inch or less.
Do not exceed ½ inch seeding depth. Results from a Utah study indicate
that broadcast seeding followed with a roller packer results in very
good stands.

Well established stands may remain productive for 3 to 4 years if not
adversely affected by cold winters. However, in most cases producers
over-seed fields with up to 5 pounds of perennial ryegrass seed per acre
each year in late fall or early spring to maintain fully productive
stands.

##### Management {#management .Header-3}

Perennial ryegrass is generally cut for hay when seed is in the
soft-dough stage. Perennial ryegrass responds well to good management,
such as intensive rotational grazing and fertilizer applications.

Perennial ryegrass performs best when used in intensively managed
pasture. It requires very accurate irrigation water management and
fertilizer management. If either irrigation or fertilility requirements
are not met, it will immediately cease growth.

Perennial ryegrass forage production can be improved with split
applications of nitrogen. It is recommended that fertilizer
recommendations be based on soil tests. However, rates approximating 45
pounds per acre of nitrogen following each grazing cycle has resulted in
excellent overall production. If only one application is economically
feasible, then apply 150 pounds of nitrogen per acre in the spring.

Perennial ryegrass is most productive and nutritious when livestock are
turned into well established pastures with six to eight inches of growth
and quickly grazed to three inches. Livestock should then be removed to
allow plants to regrow. Regrowth periods vary from about 14 to 28 days
depending on the local climate and time of year. The peak growth period
is from mid May through June. In the Intermountain West, during July and
August, when temperatures exceed 80^º^ F, perennial ryegrass production
normally declines due to high temperatures, water stress and long day
lengths. With proper fertilization and irrigation water management,
perennial ryegrass will maintain fair growth during the heat of the
summer. A second peak growth period can be expected when temperatures
cool in the fall. Perennial ryegrass can be allowed to attain twelve
inches of growth, but should not be allowed to go to seed because the
plants will not re-grow readily or maintain high nutrition and
palatability.

The disadvantage of perennial ryegrass in the Intermountain West and
Rocky Mountains is that it is not as winter hardy as other proven
irrigated pasture grasses (orchardgrass, meadow brome, intermediate
wheatgrass, pubescent wheatgrass and tall fescue). Winter hardiness data
regarding perennial ryegrass is limited, thus recommendations of
released varieties to farmers and ranchers are difficult. New Zealand
varieties of perennial ryegrass tend to produce more than meadow brome,
intermediate wheatgrass, pubescent wheatgrass and mountain brome the
first growing season. However, in the Intermountain and Rocky Mountain
regions, stands are commonly lost during the winter. In a trial near
Shelley in eastern Idaho, the Mara variety persisted for more than 5
years, but it did not producing as much as other irrigated pasture grass
species. Winter hardiness is thought to be associated with lack of
dormancy in the fall and stands have also been lost during dry periods
when adequate irrigation water was not available during growth.

##### Pests and Potential Problems {#pests-and-potential-problems .Header-3}

Perennial ryegrass contains a fungal endophyte, *Acremonium lolii,*
which is linked to the occurrence of a neurological disorder in
livestock known as ryegrass staggers. There have been reports of
ryegrass staggers in western Oregon and California, but not in the
Intermountain or Rocky Mountain West.

##### Cultivars, Improved, and Selected Materials (and area of origin) {#cultivars-improved-and-selected-materials-and-area-of-origin .Header-3}

Most forage type perennial ryegrass varieties were developed for
short-rotation pasture and green-chop. There are many releases on the
market that were bred in either New Zealand or Holland where most of the
research for highly productive and nutritious varieties has taken place.
Perennial ryegrasses are divided into diploid and tetraploid varieties.
The tetraploid varieties tend to be more upright and somewhat better
forage producers. The diploid varieties tend to be more persistent under
grazing conditions. The New Zealand varieties generally tend to grow
earlier in the spring and later into the fall. A plot of Zero Nui (a New
Zealand variety) in the Pocatello, Idaho area and pastures near Preston,
Idaho winter killed. The Holland varieties generally go dormant earlier
in the fall. Pastures and plots of Holland varieties survived well at
Pocatello and Preston.

Due to the large number of cultivars currently on the market, it is
recommended that you consult a seed supplier in your area for up-to-date
cultivars and blends. When requesting seed, ensure that you request a
forage type perennial ryegrass if forage production is your goal.

#####  {#section-1 .Header-3}

Perennial ryegrass cross-pollinates freely with annual and Italian
ryegrass, so many hybrid types of ryegrass have developed. It is
difficult to maintain perennial ryegrass genetic purity; consequently,
Italian ryegrass is marketed as common ryegrass or domestic ryegrass,
and it is often a mixture of annual and perennial species. There is no
certification of this seed since pure varieties of Italian ryegrass are
almost non-existent.

There are many varieties of perennial ryegrass available for turf
application. Newer turf-type varieties are often intentionally infected
with an endophytic fungus to improve stress-tolerance.

##### References {#references .Header-3}

Asay, Kay. 1996. *Personal Communication*. ARS, Utah studies.

Cash, Dennis and Howard Bowman. 1995. *Be Cautious With New High
Yielding Forage Grasses*. Western Beef Producer. page 8.

Engle, Scott and Dan Ogle. October 1996. *Perennial Ryegrass for
Irrigated Pasture in Southern Idaho and Northern Utah*. USDA -- NRCS,
Boise, ID. 4 p.

Gould, F.W. and R. B. Shaw. 1983. *Grass Systematics*. 2d ed. Texas A&M
Press, College Station. 397pp.

Jensen, Kevin, Howard Horton, Ron Reed and Ralph Whitesides. 2001.
*Intermountain Planting Guide*. USDA, ARS and Utah State University.
Pages 58- 59.

Kaye, John. 1995. Modern Forage Systems, Inc. booklet. 12 p.

Ogle, D., L. St. John, M. Stannard, L. Holzworth. 2008. *Grass,
Grass-Like, Forb, Legume and Woody Species for the Intermountain West.*
Natural Resources Conservation Service. Boise, Idaho. Idaho Technical
Note No. 24. 43p.

Peterson, J.S. 2002. *Perennial Ryegrass Plant Fact Sheet*. USDA, NRCS,
National Plant Data Center, Baton Rouge, LA. 2p.

Shewmaker, G. E. 2005. *Idaho Forage Handbook.* Third Addition.
University of Idaho Bulletin 547. 99p.

#####  {#section-2 .Header-3}

##### Prepared By {#prepared-by .Header-3}

Dan Ogle, USDA NRCS Idaho State Office, Boise, Idaho

Scott Engle, USDA NRCS Pocatello Field Service Center, Pocatello, Idaho

Glenn Shewmaker, University of Idaho, Twin Falls, Idaho

##### Species Coordinator {#species-coordinator .Header-3}

Dan Ogle, USDA NRCS Idaho State Office, Boise, Idaho

##### Edited: 042908 jsp; 043008 dgo; 080702 jsp {#edited-042908-jsp-043008-dgo-080702-jsp .Header-4}

For more information about this and other plants, please contact your
local NRCS field office or Conservation District, and visit the PLANTS
Web site\<[http://plants.usda.gov](http://plants.usda.gov/)\> or the
Plant Materials Program Web site
\<[http://Plant-Materials.nrcs.usda.gov](http://Plant-Materials.nrcs.usda.gov/)\>

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