David M. Kopec, Extension Turfgrass Specialist
The use of ryegrasses for turf has exploded in the last twenty years. There are probably over 125 varieties of perennial ryegrass for turf. These are usually sold as blends (two or more varieties of perennial ryegrass) in the homeowner market . Examples of a perennial ryegrass blend would be a three way blend of "Affinity", "Quickstart" and "Allure". All three of these are perennial ryegrasses. The scientific name of perennial ryegrass is Lolium perenne. In general, perennial ryegrass is used at the low elevations for overseeding bermudagrass in the late summer, early fall. At higher elevations (4500 ft. and above) ryegrass is usually sold as a component of a seed mixture. It is included with other compatible seed species like Kentucky bluegrass (KBG) and fine leaf fescue. In these "high elevation mixes" the KBG is about 60% of the mixture and the other 40% is split between perennial ryegrass (20%) and fine leaf fescue (20%). The advantage of perennial ryegrass is that it germinates and emerges quickly.
When used as an overseed grass at lower (desert) elevations, perennial ryegrass can be mowed at base heights ranging from 5/32" on a golf course to 3" on a home lawn. At low elevations, ryegrass should die out by mid-June. It can persist in shady areas where the bermuda is weak and soil moisture is not limiting. At high elevations it will remain for a long time. It will eventually be squeezed out by the KBG.
Annual ryegrass is Lolium multiflorum. It is a true annual, in that it will die after one season, no matter where it is grown. Annual ryegrass is used for overseeding at low elevations in the late summer, early fall. Its predominate use is for homeowner lawns (at overseeding) and not for parks, sport turf or golf courses. Annual ryegrass is much lighter in color and has much wider leaves than perennial ryegrass. The leaves are further apart on the stem. This is why annual ryegrass requires a higher base mowing height than perennial ryegrass. A base height of 2.0 inches (or higher) is satisfactory for annual ryegrass. Annual ryegrass is often sold as "Oregon Grown Grass Seed". There are varieties of annual ryegrass on the market and they are usually used for forage purposes. Left-over seed is sometimes sold for lawn purposes. A widely used annual ryegrass for pasture (and left-over for lawns) is "Gulf" annual ryegrass. A 25 or 50 lb. bag of annual ryegrass may not say what variety of seed it contains. In fact, in 90 out of 100 cases, it won't. Never mix annual ryegrass and perennial ryegrass together. They are not compatible in color, leaf width and mowing compatibility.
Hybrid or Intermediate Ryegrass:
This is a "new" grass first developed about ten years ago. Hybrid ryegrass is the result of pollinating perennial ryegrass plants with pollen from annual ryegrass. The result is plant which is 50/50 genetically of the two species. The resultant plant is called Lolium hybridum. For turf, the idea is to incorporate some of the better turf qualities of perennial ryegrass (Lolium multiflorum) into a plant which will fade away in the spring (like annual ryegrass--Lolium multiflorum). Most of the hybrid ryegrasses for turf have looked much more like the "annual" parent than anything else. There is a slight increase in turf performance over pure annual ryegrass in some of the early turf hybrids such a "Transtar" and "Froghair". A newer hybrid ryegrass (experimental number only at this time) has better looking turf and approaches the look of an old fashioned perennial ryegrass such as "Linn". In other words, this hybrid has attributes of both species and looks better than the previous hybrid ryegrasses. Remember, hybrid ryegrass is used for overseeding. It should not be selected as a permanent turf or as a component for a high elevation mixture (mixed with KBG or fine fescue).
Issued in furtherance of Cooperative Extension work, acts of May 8 and June 30, 1914, in cooperation with the U.S. Department of Agriculture, James A. Christenson, Director, Cooperative Extension, College of Agriculture & Life Sciences, The University of Arizona. The University of Arizona is an equal opportunity, affirmative action institution. The University does not discriminate on the basis of race, color, religion, sex, national origin, age, disability, veteran status, or sexual orientation in its programs and activities.