Field and controlled environment studies were conducted to evaluate the effects of certain environmental factors on the persistence of buried seed of annual ryegrass (Lolium multiflorum Lain.), a free‐volunteering species; and perennial ryegrass (Lolium perenne L.), nonpersistent species. Buried seed of annual ryegrass persisted in both nondormant and dormant condition. Buried seed of perennial ryegrass lost virtually all viability after 60 days of burial in the field. This dissipation occurred largely via in situ germination. Dormancy was induced in annual ryegrass when seeds were buried in cold, wet soils. High soil temperature associated with intermediate soil moisture level was effective in depleting viable seed through in situ germination. Loss of buried seed viability increased with soil temperature and moisture.