Much like some animals, most types of lawn grasses “hibernate” during winter, when their growth drastically slows during cold temperatures. Although cool-season grasses (tall fescue, bluegrass and ryegrass) remain green, most warm-season grasses (bermudagrass, zoysiagrass, St. Augustinegrass and centipedegrass) typically start to discolor and turn tan after average temperatures drop under about 50°F and particularly after the first hard frost of late fall. This is the way the grasses protect themselves from bitter, sub-freezing temperatures.
However, in most cases (unless your area experiences prolonged periods of very cold temperatures), lawn grasses remain alive during their long winter’s nap. They then resume growth when warm, sunny spring weather returns (just like trees that regrow their leaves in spring).
Mowing is typically not necessary in winter, but it’s important not to let fallen leaves remain on the surface of the lawn. Doing so can smother the grass plants, create conditions favorable for turfgrass diseases and possibly invite insects and voles to burrow underneath.
Even though the grass on top may be dormant now, grass roots still continue to grow (although slowly) throughout winter unless the soil is frozen. That’s why it’s important to continue to irrigate your lawn, especially during dry, warmish and windy periods. Desiccation (extreme drying of the grass in winter) can lead to winterkill and necessitate the replacement of dead grass in spring.