Lolium multiflorum aka Annual Ryegrass

Lolium multiflorum is known as Italian or annual ryegrass. It belongs to the grass family, Poaceae. Its native range spans Macaronesia, the Sahara, and the Mediterranean. It extends east to Central Asia and the Himalaya. People now grow it widely, including across the United States. It grows in meadows, along roadsides, and beside fields. It is not native to Britain or Ireland.

This fast-growing grass forms clumps with many leaves near the base. It can live as an annual, biennial, or perennial. Plants reach about 2–3 feet (0.6–0.9 metres) tall. NC State also lists a much shorter height range. That range is 0.17–0.5 feet (0.05–0.15 metres). Its listed spread reaches 0.83 feet (0.25 metres). The narrow green leaves have sharp tips and smooth edges. Their surfaces lack hairs, and the undersides have a gloss. The RHS describes the foliage as partly evergreen.

The flowers grow in spikes with spikelets on alternate sides. These spikes measure about 0.5–0.83 feet (0.15–0.25 metres) long. NC State describes flowering from spring through fall. Its flower table also lists winter bloom and white flowers. Each fertile floret forms a long grain as it ripens. The plant grows best in mild climates with moist, rich soil. Full sun suits it, though NC State also lists partial shade. It accepts several soil types and needs good drainage. The RHS lists acid, neutral, and alkaline soils as suitable. Hardiness ratings are USDA zones 4–9 and RHS H5. NC State warns against harsh winters and hot, dry summers.

Gardeners use this grass as green manure on empty vegetable beds. They cut it down and dig it into the soil. This adds organic matter and helps improve soil structure. Farmers also grow it for cover crops and silage. It can provide short-term winter lawn cover and withstand foot traffic. NC State advises against using it for a lasting lawn. Plants may die in late spring as heat rises. Seeds can sprout within days and form a crop within weeks.

Seed production can make this grass a garden nuisance. It can invade farm land and native habitats in temperate areas. The RHS advises digging green-manure crops in before April. It reports few pests, but grey leaf spot may occur. NC State also lists wireworms, green June beetles, and grey snow mold. Plants For A Future records no known food or medicinal uses. It lists no known hazards, rather than proof of safety.