Cool-Season vs. Warm-Season Grass: What’s the Difference?

There are two main types of lawn grass: cool-season grasses and warm-season grasses. Cool-season grasses grow best in regions with cold winters and mild summers. Warm-season grasses thrive in regions where winters are mild and summers are hot. Common cool-season grasses include Kentucky bluegrass, ryegrass, and fescue. Bermuda grass, zoysia, and St. Augustine are common examples of warm-season grasses.

Cool-season grass vs. warm-season grass

What are Cool Season Grasses?

Cool-season grasses are species that thrive in regions with cool fall weather, snowy winters, and shorter summers. Cool-season grasses can tolerate a summer heat wave but they will struggle if planted in very hot regions. These grasses experience their strongest growth during “cool seasons,” especially fall and spring.

Common Cool-Season Grasses:

  • Kentucky bluegrass
  • Fescue
  • Ryegrass
  • Bentgrass

You will find cool-season grasses planted in the northern half of the United States because they remain green in low temperatures. A cool season grass will begin to green up early in spring, even if the nights are still cold. Additionally, cool-season grasses remain green in fall, sometimes even past the first few snowfalls.

What is Warm-Season Grass?

Warm-season grass refers to any type of grass that grows best in regions with long summers and short winters. Grasses in this group experience their strongest growth during the “warm season,” so you can expect a warm-season lawn to thrive during summer.

Common Warm Season Grasses:

  • Bermuda grass
  • Centipede grass
  • Bahia grass
  • St. Augustine
  • Zoysia

Once temperatures drop in fall and winter, warm-season grasses quickly turn brown and enter dormancy. This makes them poor choices in colder regions, since you will be left with a brown lawn for most of the year. So, these grasses are often grown in the southern third of the United States.

What Type of Grass Should You Grow?

Whether you should grow cool or warm-season grass depends on where you live. Cool-season grasses are the best choice if you’re growing a lawn in the Northeast, Midwest, Mountain States, or Pacific Northwest.

This map highlights where cool-season grass grows, where warm-season grass grows, and where the Transition Zone is.

Warm-season grasses are best suited for the South, Southwest, and Southern California regions of the United States. If you live in what is known as the “Transition Zone” you can choose either cool-season or warm-season grass.

The Transition Zone: Which Grass Type is Best?

The “Transition Zone” on the US map indicates a region where both cool-season and warm-season grasses can grow well. The transition zone includes the Mid-Atlantic states, Lower Midwest, as well as parts of the South, Southwest, and California.

With new record highs being set in these regions year after year, it’s become increasingly popular to plant Transition Zone lawns with warm-season grasses, such as Bermuda grass or Zoysia. So, if you’re looking to replant your lawn in the Transition Zone, I recommend a warm season grass.

How Do You Care for Cool Season Grass vs. Warm Season Grass?

In addition to different growing regions, cool-season and warm-season grasses have a different care calendar. Here are the key differences:

Cool-Season Grasses

  • These varieties experience their strongest growth in fall.
  • Fall is the best time to overseed, seed, or sod a cool-season lawn.
  • Invasive lawn tasks like dethatching and aeration are best done in the fall.

Warm-Season Grasses

  • Grasses in this family have their biggest growth period in spring.
  • Spread warm-season grass seed or install sod in spring.
  • Spring is the best time to scalp, dethatch, or aerate warm-season lawns.

Although all lawn grass may seem the same at first glance, this isn’t always the case. By knowing the difference between cool and warm-season grass you can better understand and take care of your lawn.

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