Generally, cool-season grasses are best suited for moist, northern climates, where summers, although warm, are relatively short, and winters are cold. Such grasses also do well in high elevations with adequate rainfall and coastal areas where temperatures are moderate — temperatures don’t stay above 90 degrees for long periods.
Cool-season grasses grow actively in the cool weather of spring and fall at temperatures averaging 60 degrees F to 75 degrees F. As summers get warmer, cool-season grasses grow slower and are subject to more disease problems. These grasses also grow more slowly in summer and may turn brownish and go completely dormant when the weather is dry and hot for long periods of time. Proper watering keeps cool-season grasses green throughout the summer season. In hotter areas with severe water restrictions, you may have to get used to a brown summer lawn, but, never fear, fall rains usually bring dormant grasses back to lush, green life again. If a brown summer lawn isn't your idea of a good lawn, then warm-season grasses are a better choice.
You can grow cool-season grasses in climates that are more extreme (hotter, dryer summers and colder, snowier winters), but they require frequent watering in summer and go dormant in the winter, losing their lush, green color. If you live in a transitional zone between cool and warm-season climates (where the ground doesn’t freeze in winter), cool-season grasses stay green all winter. But, in such areas, you should talk to your local nursery or extension office about the most appropriate grasses or go with native grasses.
In southern climates, you can use cool-season grasses to green up winter lawns by overseeding. In the fall, evenly spread cool-season grass seed — usually a fast-growing annual ryegrass — over the lawn. When the ryegrass germinates and grows, you get a temporary green cover throughout the winter while the warm-season grass lies dormant. With the onset of spring, the cool-season grass dies out or goes dormant as the warm-season grass turns green again. In the South and West, people also use some perennial fescues and rye grasses for overseeding, but those perennials may compete with the summer grasses when they re-emerge in the spring.
The most commonly planted cool-season grasses include bent grass, Kentucky bluegrass, fescues, and ryegrass. Of those, Kentucky bluegrass has been the most commonly planted lawn for years. But new and improved varieties of tall fescue have recently increased in popularity due to its finer textures and improved qualities while maintaining greater vigor and resistance to harsh conditions, including drought and heat.
