What Are Cool Season Grasses?
Cool-season grasses are grass types that thrive in areas with cold winters and hot summers.
Cool-season grasses have adapted to grow well in areas of the country that experience tremendous temperature fluctuations: cold, freezing winters and hot, dry summers. However, these grasses grow best when temperatures are between 60-75 degree F, which is why they grow most actively in the spring and fall. Cool-season grasses are most commonly grown from seed, although sod is also available, and they grow best when they are maintained at a mowing height of 3-4 inches.
Where Do Cool-Season Grasses Grow?
Cool-season grasses grow in the upper two-thirds of the United States. In the top-third (or the area roughly defined as New England, the Upper Midwest, High Plains, Northern California, and Pacific Northwest) typically only cool-season grasses are grown. The middle-third (also known as the “Transition Zone”) is the area of the country where cool-season and warm-season grasses overlap. Cool-season grasses grow well there because they are adapted to the cold winters. Tall fescue is especially well suited for the Transition Zone because of its high heat and drought tolerance. However, some warm-season grasses also grow well there because of the hot, dry summers. Bermudagrass and zoysiagrass are the main warm-season grasses found in the transition zone because they are drought-tolerant and also able to withstand cooler temperatures better than other types of warm-season grasses. However, they often go dormant and turn brown during the winter months when temperatures are consistently below 60 degree F.
Types of Cool-Season Grasses
The most common types of cool-season grasses are Kentucky bluegrass, perennial ryegrass, fine fescue, and tall fescue. You'll often find the seeds of these grass types mixed together for different needs and uses, such as high traffic, sunny, or dense shade conditions. The most popular and most versatile cool-season grass mix is for sun and shade.