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What is Perennial Ryegrass?
Perennial ryegrass is grass species commonly classified as one of the cool-season grasses (also considered winter grass) but is broadly used across the United States, though in different roles.
Unlike annual ryegrass, perennial ryegrass in the transition zone with its temperate climate is commonly mixed with Kentucky bluegrass to render rich green grass athletic fields.
In the southern U.S., ryegrasses are used as temporary turfgrass by overseeding dormant warm-season grass – especially tall fescue grasses used in golf course fairways and home lawns.
Perennial ryegrass (Lolium Perenne) is not the family of the cereal rye, but rather the Italian ryegrass, or annual ryegrass.
They readily hybridize and produce a wide range of grasses with comparable exterior features that include traits from both species, making identification and management challenges.
In addition, Festuca can also cross with these two species in natural conditions, resulting in a two- or three-species complex.
As a result, it’s better to know what you’re getting while planting ryegrass seeds.
The National Turfgrass Evaluation Programme (NTEP) is currently evaluating 114 perennial ryegrass (Lolium perenne) species, of which 50 are commercially available [1].
NTEP does evaluations at 17 sites across 14 states (CT, IA, KS, KY, MA, MD, MN, MO, NE, NJ, OR, UT, VA, and WI).
Wear resistance, effects of environmental conditions, drought resistance, and response to pests and diseases are all measured.
Common Uses of Perennial Ryegrass
Except for golf greens, golf courses make ample use of ryegrass.
Because of its fast germination and growth habit, finding grass seed blends that don’t include perennial ryegrass is becoming increasingly difficult.
Even while potential loss from cold winters remains a concern east of the Cascades, the use of this fine-textured lawn has increased substantially.
How to Care for Perennial Ryegrass
Mowing
Today’s top cultivars can withstand mowing heights ranging from 5/8 to 2.5 inches.
Ryegrass grows best between one and two inches tall, providing the best density and lawn quality.
When mowed below 5/8-inch, ryegrass loses density and cannot remain competitive in the fairway, quickly being overtaken by bluegrasses and bentgrass.
It effectively generates a temporary lawn at low mowing heights.
Today’s commercial cultivars are cut neatly with well-adjusted reel mowers and even sharp rotary mowers, though still more difficult to mow than most other grasses.
With today’s cultivars, spring stemminess is rarely an issue.
Fertilizer
Despite all of the breeding efforts, ryegrass still requires more nitrogen than most grasses.
This can be not easy since ryegrass is highly responsive to nitrogen, and high fertilizer rates encourage excessive growth.
Due to a lack of nitrogen, ryegrass is susceptible to several diseases that induce thinning, making it vulnerable to encroachment by other grasses and moss.
In creating hybrids, developing ryegrass that performs better under low fertility should be more focused.
Dense green ryegrass turf, on average, requires four to eight pounds of nitrogen per 1000 square feet per year.
Irrigation
Among all the regularly planted cool-season turfgrasses, ryegrass still produces the least amount of thatch.
It is uncommon to locate enough thatch on the soil to necessitate dethatching.
Its tendency to thin out during the winter and earthworms’ apparent love for senescing ryegrass leaf may explain the lack of thatch production.
By the end of the winter, earthworms west of the Cascades may convert ryegrass turf into a muddy mess.
When planted on sand substrates, ryegrass can create a lot of thatch.
On sporting fields, cleated traffic grinds thatch and senescing vegetation into the surface, resulting in an organic bog prevalent on mature sand-based turf.
Make sure to water perennial ryegrass to get about one inch of water per week. This is because it will support deeper root growth.
Thatch
Among all the regularly planted cool-season turfgrasses, Ryegrass still produces the least amount of thatch.
It is uncommon to locate enough thatch on the soil to necessitate dethatching.
Its tendency to thin out during the winter and earthworms’ apparent love for senescing ryegrass leaf may explain the lack of thatch production.
By the end of the winter, earthworms west of the Cascades may convert ryegrass turf into a muddy mess.
When planted on sand substrates, ryegrass can create a lot of thatch.
On sporting fields, cleated traffic grinds thatch and senescing vegetation into the surface, resulting in an organic bog prevalent on mature sand-based turf.
Diseases
Despite the efforts of breeders, ryegrass in the Pacific Northwest continues to be plagued by a slew of disease issues.
When fertility is low, red thread, pink patch, and crown rust are prone to red thread, pink patch, and crown rust.
Brown blight affects a large number of cultivars. In the United States, ryegrass and crimson thread have practically become synonymous.
Fusarium patch and leaf spot are very common in high-fertility ryegrass.
Pink and grey snow mold can potentially cause serious injury in locations where there is a lot of snow.
To treat poor fertility disorders, apply nitrogen-based fertilizers. Fungicides are usually required to control snow molds.
Insects
The importance of endophytic fungi in mitigating damage from common insect pests is a common topic.
Many ryegrasses have endophytic fungus bred into them.
There is no evidence that fungal endophytes effectively reduce European crane fly populations.
Cold Tolerance
Many enhanced ryegrass varieties are more tolerant to broader temperate climates – even cold – than early cultivars.
Newer cultivars are far hardier than older ryegrass varieties. Hence, it is commonly used as a pasture grass and home lawn.
Perennial ryegrass starts growing in early spring to late spring and into the fall, except when the hot summer becomes dormant.
This feature allows perennial ryegrass to be used for overseeding warm-season grasses or warm-season turfgrasses.
Shade tolerance
In the shadow, ryegrass has never been a terrific grass.
The best new cultivars are still thin and feeble in deep shadow, and Kentucky bluegrass quickly overtakes them.
In addition, moss frequently plagues shaded ryegrass lawns.
Ryegrass has a position in shade culture as a nurse grass for better-adapted species, and it will provide fast cover in the spring when the turf is emerging from its winter hibernation.
Don’t use perennial ryegrass as a permanent lawn in the shade.
Persistence
Ryegrass can be pretty persistent with correct fertilization and continuous maintenance, but it will permanently lose out against bentgrasses and bluegrasses if present.
Ryegrass is essentially a transition grass replaced after a few years by other better-adapted grasses.
Other types of grass to consider
If you are looking for other varieties of grass to grow in your yard, check out our other related posts:
Other types of grass to consider
If you are looking for other varieties of grass to grow in your yard, check out our other related posts:
FAQ
Does perennial ryegrass come back every year?
Perennial ryegrass, in contrast to its sister grass, Italian ryegrass, is a multi-year lawn that returns from hibernation on an annual basis during hot summers.
Does perennial ryegrass die in the summer?
Perennial ryegrass goes dormant during the summer months, but it does not die off. This is especially true during periods of extreme heat or drought. The blades of dormant ryegrass become yellow and lose their rich green color as the season progresses. Perennial ryegrass will reappear as soon as colder weather arrives, and its color will shift to its typical green throughout the winter months.
Does perennial ryegrass grow better in the sun or shade?
Perennial ryegrass performs quite badly when grown in the shadow. It is likely that if your lawn has any meadow grasses of bluegrass type, they will take over and replace the ryegrass in the shaded parts.
In Summary
Ryegrass is an excellent utility grass that works well alone and in mixtures with other species.
Its strong suit is still its rapid establishment capabilities, ability to germinate in cool weather, wear tolerance, and attractive appearance when regularly fertilized.
Breeders have consistently improved ryegrass, as evidenced by its improved texture, mowing quality, cold tolerance, and slower vertical growth rate.
Its most significant weaknesses remain in the form of high nitrogen requirement, poor shade performance, earthworm attractiveness, and poor long-term competitiveness with other grasses.
With the rapid development of new cultivars, we expect to see a steady improvement in turf quality.
References
- National Turfgrass Evaluation Program. (2020). 2016 National Perennial Ryegrass Test. URL: https://ntep.org/data/pr16/pr16_21-9/pr16_21-9.pdf/
- Cook, T. (n.d.). Perennial ryegrass – Lolium perenne L.. Oregon State University, College of Agricultural Sciences, Department of Horticulture. URL: https://agsci.oregonstate.edu/beaverturf/perennial-ryegrass-lolium-perenne-l/
- About/Mentions: Perennial ryegrass, Lawn, Gardening, Sod
Lindsey Hyland grew up in Arizona where she studied at the University of Arizona’s Controlled Environment Agriculture Center. She continued her gardening education by working on organic farms in both rural and urban settings. She started UrbanOrganicYield.com to share gardening tips and tactics. She’s happy to talk about succulents and houseplants or vegetables and herbs – or just about anything in a backyard garden or hydroponics garden.