Get to Know Your Warm-Season Grasses

R. L. Rhodes
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While grass may seem like the simplest plant in your landscape, being able to identify your grass by type will allow you to tailor your lawn care to its needs.

Grasses that thrive at 70 degrees Fahrenheit and higher will require different treatment from cool-weather varieties. Use the following guide to help identify the variety in your yard.

Types of turfgrass

Broadly speaking, turfgrasses can be divided into two groups, based on the climates that suit them best, temperate or tropical. The latter group is commonly known as the warm-season grasses.

If you happen to be a scientist, you may be able to distinguish between them by looking at the enzymes used to carry out photosynthesis.

If you don’t happen to have a microscope handy, it’s far easier to pay attention to the life-cycle of the lawn. Warm-season grasses generally grow best when the soil temperature reaches 70 degrees Fahrenheit or higher. During the fall and winter seasons, they go dormant and may turn brown. Because the first year or two after planting is usually given over to establishing an extensive and efficient root base, warm-season grasses may look like they’ve failed, even when they’re actually doing quite well.

There are hundreds of varieties of warm-season grass, but some of the most common in North America are bahiagrass, buffalograss (also known as St. Augustine grass), centipedegrass, and Zoysiagrass. Knowing the basics of grass anatomy will help you spot the differences between them.

Structural elements

Images: Harry Rose/Flickr

Left: A spike-type seed head on zoysiagrass.

When identifying the type of warm-season grass on your lawn, it helps to be familiar with the structure of turfgrass. From the ground up, the body of a grass plant is made up of its roots, stem, leaves and seed head.

The seed head can be helpful in identifying grass types, but usually gets lopped off when you mow your yard, so may not be available. If some portion of the grass in your yard is full-grown, you can look for differing types of seed head described as panicle, spike and receme. Bahiagrass, for example, is easily identified by its characteristic Y-shaped seed head. Those branches, which are lined with pepper-like seeds called “spikelets,” are referred to as racemes, and are much more common among warm-season grasses than their cool-season counterparts. Panicle seed heads are like miniature trees—a central stem with the spikelets growing at the end of branches. By contrast, the spikelets on the spike type seed heads grow directly from the main stem.

The leaves make up most of what we think of as turfgrass, and they can be divided into three parts: the sheath, the collar and the blade. Differences in the shape of the blades can help us distinguish between varieties. If you place a blade of grass on a flat surface, some will lie flat while others are keeled like a boat. Some are glossy underneath while others are matte. And some have a single mid-vein running down the length of the blade while others are ribbed with multiple small veins.

Image: Harry Rose/Flickr

A carpetgrass stolon.

Botanists use the word “vernation” to describe the growth and arrangement of new leaves on a plant. In cool-season grasses, vernation can be either folded or rolled. You can check the vernation of your grass by cutting a cross-section and looking at the newly formed leaves beneath the collar, or by trying to roll a shoot of grass between your fingers. If the shoot flattens, it likely has folded vernation.

Finally, we can talk about how grass plants propagate. Some use rhizomes, underground shoots that spring up elsewhere to produce new plants. Others use stolons, which are a like above-ground rhizomes that put out roots at intervals along its length. Some use neither rhizomes nor stolons, but reproduce in tufts-like bunches.

With those structural features in mind, you’ll be ready to identify different types of turfgrass.

Warm-Season Grasses

When identifying grasses, it’s a good idea to take samples from different areas of your yard, as grasses of different types sometimes grow in close proximity to one another. Refer to the table below to help identify the grasses in you find.

Type of grass

Seed head

Leaves

Vernation

Propogation

Bahiagrass Y-shaped raceme Flat, long, pointed Rolled Rhizomes, occasionally stolons
Bermudagrass Raceme Rough-edged, sharp-pointed Folded or rolled Rhizomes & stolons
Buffalograss Spike Keeled, mid-vein Folded Stolons, rarely rhizomes
Carpetgrass Raceme Keeled, broad, with rounded points Folded Stolons
Centipedegrass Single, purplish raceme Keeled, mid-vein, with rounded points Folded Stolons
Zoysiagrass Short, pointed spike Flat, stiff, sharply pointed Rolled Stolons & rhizomes

If you’re unsure whether or not your grass matches, or suspect that you have a less common variety of cool-season grass, take some samples in to your nearest Extension Service office and let the experts take a look.

Once you’ve identified your warm-season grass, head to the Home Depot to buy seed or sod for overseeding or patching, as well as fertilizer for boosting the growth and health of your lawn. And keep current with the Garden Club for more articles in our series on the right lawn care for your grass type.

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