Difference Between Cool Season vs. Warm Season Turfgrass

By Anthony Makara, Fairfax Master Gardener
Aside from having the color, Green, what else is there to know about a lawn? For the homeowner, it’s knowing which turfgrasses are better suited for our area of Northern Virginia, and of those, what additional traits are important. Is a certain turf more disease-prone? How does it look in the summer? How much care does it require? How fast or slow does it grow?

tall fescue

Tall fescue

Lawn turfgrasses are one of two types: cool season or warm season. The names connote the temperatures where they will thrive best. Here in Northern Virginia, we are in a lawn “transition zone,” which means that several grasses from each category will do reasonably well.

Cool season turfgrasses
These turfgrasses will grow best in temperatures of 60 to 75 F and are the first to emerge in the spring. When soil temperatures attain 40 to 60 F, root growth becomes very active. This results in major top growth early spring to early summer. The hot summer degree readings, and possible drought, cause the growth activity to drop sharply, and damage could result if conditions are severe. When the weather moderates in the fall, these turfgrasses are again in their comfort zone, and growth once again returns. If lawn replenishment efforts are needed, including re-seeding and fertilization, fall is the time to do it. Typical cool season turfgrasses found in Northern Virginia include:

Tall Fescue A sun-loving turf with average shade tolerance. Good overall performance in the Northern Virginia lawn. Does not do well in deep shade. Very deep root system that grows as a “bunch”; i.e, does not have expanding rhizomes. A good choice for low- to moderate-maintenance lawns.
Kentucky Bluegrass Sun-loving with a dark green color. Does poorly if receiving less than six hours of full sun per day. Grows in a spreading fashion via rhizomes forming a dense sod. Best during cool, moist weather on well-drained, fertile soils. More prone to turf diseases. Very slow germinating.
Fine Fescue For general use in low maintenance areas or in partial to full shade. Less than four hours of sunlight per day. Blade is much thinner than other cool season turfgrasses. Almost n