The Temperature Range for Winter Ryegrass

Germination

• Winter rye seed will germinate at temperatures between 34 and 75 degrees Fahrenheit, but germination is best when the soil temperature is between 40 and 60 degrees F. Soil temperature is most closely related to nighttime temperatures. Plant winter rye when minimum temperatures have been 50 degrees or lower for a few nights in a row. Water lightly two to three times a day until the seeds germinate, then water less frequently but more deeply.

Growth

• Winter ryegrass will grow at temperatures down to 33 degrees F and will stay green at 30 degrees. It can even survive and stay green under snow for short periods of time. It will go dormant when the temperature is below 30 degrees for prolonged periods, but will resume growth as the temperature rises above freezing. When the temperature is above 75 degrees, winter rye stops growing.

Seed Production

• In the spring, days with 14 hours or more of daylight will make the ryegrass stop growing and cause it to begin seed production. In lawns, the grass should die out when the temperature rises above 75 degrees, allowing the warm season grass to take over again. During a cool spring, the ryegrass may remain green and should be mowed as short as possible as the warm season grass begins to grow.

Limitations

• As an annual, winter ryegrass is not suitable for a permanent lawn or pasture, but can be used as a nurse crop with other grasses or legumes. It is more coarse-textured than most lawn grasses, and cover crops should be incorporated into the soil while the grass is still green and succulent. It is also very susceptible to disease when the temperature is above 75 degrees, especially in moist conditions.