Comparing Cool Season and Warm Season Grasses

Turf species are broken down into two categories: cool season and warm season grasses. As the name implies, cool season grasses prefer the cooler weather of northern climates. They grow the fastest during the fall and spring, preferring temperatures between 50 and 80 degrees. Cool season grasses stay green until temperatures drop below 32 degrees F for extended periods and can survive subfreezing temperatures. Conversely, warm season grasses prefer the heat of southern climates. They grow the fastest during the summer, preferring temperatures between 80 and 95 degrees. They lose their green color if winter temperatures drop below 50 degrees F for extended periods of time; some species cannot survive extended periods of subfreezing temperatures.

Transition Zone Grasses

Some species can survive in both their preferred climate and in the transition zone: the area which is both hot in the summer and cold in the winter. In the United States, the transition zone encompasses the eastern central and the mid-central regions of the country. Bermuda and Tall fescue type grasses are the most commonly grown grass types in the transition zone. Bermuda being a warm season grass is more widely grown in the southern edge of the transition zone. Tall fescue, an adaptable cold season grass, is generally the choice for central and northern transition zone areas.



Grass species tolerances

In addition to preferring warmer or cooler temperatures, different species also have different tolerances for a number of traits (drought tolerance, shade tolerance, etc.) also with varying degrees of tolerances. Below are relative rankings for the following traits in common lawn turfgrasses: heat, cold, drought, and shade.

Cold Season Grasses

Cold Season Grass types include: Tall Fescue, Fine Fescue, Kentucky Bluegrass, Perennial Ryegrass, Annual Ryegrass.

Warm Season Grasses

Warm Season Grass types include: Zoysia, Bermudagrass, Kikuyugrass, Bahia Grass, St. Augustine, and Centipede Grass.