General Info about Annual Ryegrass

Annual ryegrass (Lolium multiflorum) is a small seeded grass that can be grazed in spring or fall, hayed, used as a cover crop, plowed as green manure or used as a nurse crop for fall-seeded legumes.

Around the world, annual ryegrass has many different agricultural, horticultural, and urban uses.

Common Name: Annual ryegrass or Italian ryegrass. Annual ryegrass should not be confused with “Rye” or Cereal Rye, a completely different species.

Scientific Name: Family: Poaceae, Genus: Lolium, Species: multiflorum

Origin: Introduced to the USA from Europe

Description: Seeds are small, averaging 217,000 seeds/lb. Bushel weight: approx. 26 lb. ryegrass_drawing

Annual ryegrass is a very competitive winter annual, with good seedling vigor, fast germanation (with adequate moisture) and rapid establishment. Annual ryegrass is a bunch grass, yellowish-green at the base, with long glossy green leaves up to 12” each. The plant may reach up to four feet in height at maturity. In the context of cover crops, however, annual ryegrass is killed in the spring before it reaches seed formation stage.

Cold Tolerance: Annual ryegrass is a cool-season annual grass that – with good snow cover – possesses good cold tolerance. Not as winter hardy as cereal rye or winter wheat.

Geographic Range: While annual ryegrass can be found throughout the US, it has much greater persistence in temperate climates. It is used in the south to fill in during winter months for other grasses that thrive only in summer months. In central and northern states, annual ryegrass is a popular cover crop, wintering over well especially when snow cover can protect the plant from excessive temperature fluctuations.

Growing Requirements: Annual ryegrass grows vigorously under a wide range of soils and climates. It is tolerant of wet soils and temporary flooding, will grow in sandy soils but is better adapted to heavy clay or silty soils. It is a great nitrogen scavenger and can assimilate as much as 200 lbs N/acre/yr. Most of that N then becomes available to crops following, thus saving on fertilizer input. It also responds well to P on eroded soils. Annual ryegrass tolerates a pH range of 5-8 with the optimum between 6 and 7.

Annual ryegrass has thge greatest rate of seedling growth among cultivated cool-season grasses if soil moisture is adequate and soil temperatures are above 60 degrees F.

Seed Longevity: Under field conditions seed longevity is relatively short (3-4 years), however seed longevity when stored under dry cool conditions is long.

Flowering: May-July

Seed Production: The Willamette valley in Oregon is the primary region of annual ryegrass seed production.