How Tall Does Perennial Rye Grow in the Winter?

Typical Growing Season

• Autumn and spring are the two main growing periods for perennial ryegrass, while extreme temperature swings in the summer and winter create a dormancy effect. If you seed ryegrass between October and November, it takes only about two weeks to see a growth of approximately 2 inches in height. Quickly establishing in the fall, ryegrass protects itself from winter cold by deeply seating its roots in the soil until spring arrives with warmer temperatures. It may appear that the grass is growing in the winter because ryegrass retains its green hue, unlike other grass species that take on a brown appearance.

Winter Dormancy

• Winter provides a resting period for the ryegrass. Without long days and warmer temperatures, photosynthesis wanes and causes dormancy. After this resting period, a flush of new growth appears in spring. In fact, up to 60 percent of grass growth occurs in spring alone, according to Cornell University. Although perennial ryegrass prefers cooler temperatures, winter cold still stops foliage growth completely.

Temperature Influence

• Perennial ryegrass displays peak growth between 60 and 70 degrees Fahrenheit. Growth stops altogether when temperatures stay consistently below 50 F. Heat waves, however, may trigger some winter growth. Once the warm weather subsides, the new growth stops in response to the cooler temperatures. If you have new seedlings responding to the heat wave, you may end up with failed grass patches come spring. These seedlings do not have the extensive root systems needed to survive the extended winter months.

Winter Root Action

• Fall and winter growth that does occur is typically at the root level. As days grow shorter, perennial ryegrass responds by concentrating its energy production on root growth and nutrient storage. Because of this extensive root action, you should fertilize during the autumn for the best grass uptake and response. A well-established lawn with a nutrient-full root system survives the winter months well when photosynthesis is at its lowest; it must rely on stored nutrients since winter growth is fully stunted and not able to produce energy for survival.