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What Are Cool Season Grasses?
What Are Cool-Season Grasses?
The grass family behind most Northern lawns—built to thrive in spring and fall, and rest through summer and winter.
If your lawn is greenest in April and October and looks a little tired by August, you're almost certainly growing cool-season grass. This category covers the majority of lawns across the northern two-thirds of the US, and understanding what makes it tick is the key to getting the timing right on everything from planting to feeding.
What Are Cool-Season Grasses?
Cool-season grasses are grass types that grow best in areas with cold winters and hot summers, doing most of their growing during spring and fall rather than the heat of summer. They're typically established from seed, mowed to about 3-4 inches tall, and stay green through most winters rather than going fully dormant.
Lawn Library
Cool-season grass: a grass type adapted to grow most actively when air temperature is between about 60-75°F—spring and fall—and to slow down or go semi-dormant during summer heat. Cool-season grasses are cold-hardy and are typically established from seed rather than plugs or sod.
Where Do Cool-Season Grasses Grow?
Cool-season grasses dominate the northern third of the US—New England, the Upper Midwest, the High Plains, Northern California, and the Pacific Northwest—where they're essentially the only lawn grass option. They also grow in the Transition Zone, a wide band through the middle of the country where both cool- and warm-season grasses are viable. Tall fescue in particular is a popular cool-season grass choice for the Transition Zone because of its combination of heat, drought, and cold tolerance.
Lawn Library
Transition Zone: a wide band across the middle of the US (roughly Kansas through the Mid-Atlantic) where summers are hot enough to stress cool-season grass and winters are cold enough to stress warm-season grass. Homeowners here can often grow grass types from either category.
What Are the Types of Cool-Season Grass?
Four grasses make up nearly every cool-season lawn, often blended together rather than planted alone. Each has a full growing guide with care steps.
Kentucky Bluegrass
Kentucky bluegrass is dark green with an aggressive, self-spreading growth habit that fills in minor damage on its own. Medium tolerance for drought, foot traffic, cold, and heat, and low-to-medium shade tolerance, so it's usually blended with fescue for shadier yards.
See the full growing guide: How to Plant and Care for a Kentucky Bluegrass Lawn.
Perennial Ryegrass
Perennial ryegrass is a quick-germinating bunchgrass with fine, glossy blades. It’s the fastest-establishing lawn grass available, which makes it a favorite for patching and overseeding. High foot-traffic tolerance; low-to-medium drought, shade, and heat tolerance.
See the full growing guide: How to Plant and Care for a Perennial Ryegrass Lawn.
Fine Fescues
Fine fescues, including sheep fescue, are a group of grasses with fine-textured, gray-green blades that are built for shade. They are the go-to choice when other cool-season grasses thin out. High drought and shade tolerance, medium-to-high cold tolerance.
See the full growing guide: How to Plant and Care for a Fescue Lawn.
Tall Fescue
Tall Fescue is a deep-rooted, coarser-bladed grass with the best heat and drought tolerance of the cool-season group, making it the top pick for Transition Zone lawns.
See the full growing guide: How to Plant and Care for a Fescue Lawn.
How Do You Care for Cool-Season Grass?
Cool-season grasses generally want about 1 inch of water a week, a mowing height of 3-4 inches, and feeding four times a year to stay thick, green, and better resist stressors. Exact needs vary by type; check your grass's individual grow guide for specifics on water needs, mowing height, and feeding schedule.
When Should You Plant Cool-Season Grass?
The best time to plant any cool-season grass is fall, once air temperatures cool into the 60-75°F range and soil is still holding summer warmth; that combination gives roots time to establish before winter while avoiding the stress of summer heat. For the best seed germination, look for soil temperature between 55°F and 70°F. See your grass type's grow guide for the full step-by-step planting process.
Fall is the best time to seed cool-season lawns.
Read our Fall Grass Seeding article to find out why.
Frequently Asked Questions
Can Cool-Season Grass Grow in the South?
Generally no. Outside of the Transition Zone, most of the Deep South is too hot for cool-season grasses to survive as a permanent lawn. The exception is winter overseeding. Many Southern homeowners plant perennial ryegrass over a dormant warm-season lawn each fall purely for winter color, then let it die back naturally in spring. See How to Seed a Dormant Lawn in Winter for the full story.
What's the Difference Between Cool-Season and Warm-Season Grass?
Cool-season grass grows most actively in spring and fall and stays green through most winters; warm-season grass grows most actively in summer heat and goes brown and dormant once cold weather hits. Which one you have (or should plant) mostly comes down to where you live. See Identify Your Grass Type to confirm which category your lawn falls into, or What Are Warm-Season Grasses? for the warm-season profiles.
O.M. Scott & Sons
O.M. Scott & Sons
