Warm Season Grass vs. Cool Season Grass - How To Choose

by David Salman

Legacy buffalo grass lawn.

Planting a Waterwise Lawn From Seed and Plugs

Many homeowners are in the process of making the decision to convert their lawn to more waterwise, low-care turf grass varieties. This will be a wise choice for both their pocketbooks and the environment. When installing a lawn, unlike rolling out high-water sod, the low water/low-care lawn grass options are usually planted from seed or plugs (small rooted plants). Hence, the timing and methods used to establish a new lawn are different than when laying sod. Here are some considerations about grass types and the timing of planting to help homeowners make the right choices to get their new lawn established.

Cool Season and Warm Season Lawn Grasses Defined

The first decision to be made is to choose the best type of grass for your use and your region's climate.

There are two basic types of grasses: warm season grasses and cool season grasses. This is important information as it relates to:

  1. When are they in active growth?
  2. When it is best to plant?
  3. When do they become green at the start of the growing season and when they go dormant in the fall?
  • Warm season grasses are varieties that are in active growth beginning in late spring and go dormant in early to mid-fall. So they "green-up" in late spring when the nights begin to warm and go brown in mid-fall (late Sept.-Oct.) These grasses are very intolerant of shade. The more sun the better.
  • Cool season grasses are varieties that are in active growth ("green up") much earlier in the growing season (mid-spring) and stay green longer into the fall before going dormant in late fall. But without regular summer watering, they will go dormant in the heat of summer. These grasses will tolerate a little shade but need at least a 1/2 to 3/4 of a day of full sun.

Considerations When Choosing Between Warm and Cool Season Grasses

  • For some homeowners, having a green lawn for as long as possible, is of primary importance. So cool season lawn grasses will be their best choice. But the trade-off is that cool season grasses are not as water efficient as warm season grasses and will use noticeably more water than warm season grasses (but less than high-water Kentucky bluegrass).
  • For homeowners with properties at higher elevations (above 6 to 6,500 ft.) and more northern latitudes (Washington, northern Idaho, Montana, the Dakotas, Wisconsin, Minnesota, Michigan, New York, Vermont, New Hampshire and Maine), warm season grasses are not a good choice. Here, cool season varieties will perform best.
  • For homeowners who live in the lower latitudes of the US where summers are hot to very hot, warm season grasses are the best option. Cool season varieties will need a lot of water to keep them in active growth.

Planting Season Best Practices

The planting season for warm and cool season grasses is somewhat different.