What Is Ryegrass?


Ryegrass is a bunch grass that was brought to the United States from Europe; it is not to be confused with the plant that produces the rye grain that is used to make rye bread and whiskey. Ryegrasses are known for their ability to grow in cool weather. Perennial ryegrass is used for lawns, turf, and pasture. Annual ryegrass is seeded in the spring, often over other grasses, and lives through one winter.

Annual Ryegrass

Most of the 1.2 million acres of annual ryegrass, Lolium multiflorum Lam, also called Italian ryegrass, is grown in the southeastern United States. It is planted in the fall and used for winter pasture; it dies the next summer. Annual ryegrass doesn't do well in cold winters unless there is a good snow cover.

Perennial Ryegrass

Perennial ryegrass, Lolium perenne L., grows side shoots, called tillers, more profusely than annual ryegrass but is more susceptible to slumping growth in the summer. There are perennial hybrids with two sets or four sets of chromosomes. Tetraploid cultivars, which have four sets of chromosomes, have wider leaves, tillers and seedheads. They have higher yields and resist disease better than the diploid ryegrasses, which have two sets of chromosomes.

Seedings and Growth

You can sow ryegrass by scattering it. The problem is in getting even coverage and making sure the seeds come into contact with the soil so they can germinate. Annual ryegrass is easy to sow and grows quickly; for quality pasture, the grass needs to be grazed before it produces seed head heads. Annual ryegrass does well if it is seeded during frost; it gives higher yields than other grasses through the summer and during the seeding year. Perennial ryegrass grows more slowly than annual ryegrass, and it will not form a seed head during the year it was seeded; it will develop early heads under dry conditions the year after it was seeded.

Lawns and Turf

Annual ryegrass is often used for lawns in northern states. Both annual and perennial ryegrasses are used to overseed grass that goes dormant in the winter. This provides green lawns throughout the year. Perennial ryegrass is tough and durable; its quick germination and shiny green color plus the fine texture of recent hybrids and dense sod make it well suited for athletic fields. Many golf greens are over-sown with perennial ryegrass to give winter cover for Bermudagrass Perennial ryegrass is often sown together with Kentucky bluegrass to give the bluegrass time to get established. The two species can be mowed at the same height. Ryegrass lawns need more water and fertilizer in warm areas.

Pastures and Grazing

The compact growing habit of perennial ryegrass makes it useful for pastures in areas with heavy rain. If annual ryegrass is mixed with perennial legumes in areas of with reliable snow cover in the northern United States and southern Canada, it can live up to five years. In those conditions, it is used as grazing areas for dairy cattle.

Special Uses

Quick-growing annual ryegrass is used to provide erosion control and short-term use along highway shoulders, parks and reclamation sites. Annual ryegrass is often sown ahead of crops that are a favorite of nematodes; the grass is turned under before the new crop is planted. Annual ryegrass is sometimes planted between rows of crops to keep down weeds.


Ryegrass is susceptible to crown rust. This disease can seriously defoliate the plant.

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About this Author

Richard Hoyt, the author of 26 mysteries, thrillers and other novels, is a former reporter for Honolulu dailies and writer for "Newsweek" magazine. He taught nonfiction writing and journalism at the university level for 10 years. He holds a Ph.D. in American studies.