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Cool & Warm Season Grasses


Grass is grass, right? Nope. Not even close. As any landscape pro worth his or her salt already knows, every turf species has its own unique requirements. Consult this article as a reference for which turf to plant when.

SiteOne March 6, 2018

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Turfgrasses are categorized as either cool season or warm season, according to their optimum growth periods. Cool season grasses grow actively in the cool weather of spring and fall and somewhat slower in the heat of summer. Optimum growth temperatures range from 60-75º F. Warm season grasses grow vigorously in the summer months. The optimum growth temperature range for warm season grasses is 80-95º F. Warm season grasses will lose their color when soil temperatures fall below 50º F and will go dormant after the first frost in the fall. Full turf establishment for both cool season and warm season grasses will take two to four months.

The cool season grasses do best in the Cool Humid and Cool Arid Zones of the U.S. There are differences in cold hardiness of cool season grass species; bluegrasses, fine fescues, and bentgrasses are more tolerant of harsh winters than perennial ryegrass and tall fescues. Tall fescues have better heat tolerance than the other cool season species and are better for establishment in the southern regions, as well as in the upper portion of the Warm Humid Zone. Planting cool season grasses in late summer or fall will offer better competition against weeds and summer diseases.

Here is a list of cool season grasses with recommended planting time by zone:

Planting dates

Bentgrass:

Cool Humid, Cool Arid - August 1 to September 15

Bluegrass:

Cool Humid, Cool Arid - August 1 to September 15

The warm season grasses do best in the Warm Humid, Warm Arid, and Subtropical Zones. Many warm season grasses do not produce viable seed and must be established with sod or sprigs. Warm season grasses are generally more aggressive and tolerant of drought and heat stress. Warm season grasses are very wear and traffic tolerant. Modern turfgrass breeders have developed new varieties of Bermudagrass and Zoysia that show increased cold tolerance. Warm season grasses such as paspalum also have excellent salt tolerance.

Here is a list of warm season grasses (with seed available) with recommended planting time by zone:

Planting dates

Perennial Ryegrass

Cool Humid, Cool Arid  - August 15 to September 30

Annual Ryegrass

Cool Humid, Cool Arid   August 15 to September 30

Tall Fescue  

Cool Humid, Cool Arid, Warm Humid August 15 to September 30 

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