Highway Grass

Bahiagrass (a.k.a highway grass) is a weedy turfgrass that rears its ugly head in home lawns and along roadsides in late summer.

I hope you have been enjoying the slightly cooler weather as well as the tasty watermelons and other summer produce of late July. Today we will talk about one of the many grassy weeds that often cross our path, bahiagrass (also known as highway grass).

This time of year, we see the familiar Y-shaped seed heads of bahiagrass waving at us on roadsides and along the edges of home lawns. Bahiagrass ( Paspalum notatum ) is a tropical South American grass that is actually a tough, drought-tolerant turfgrass. It makes an excellent turfgrass in infertile soils, low-maintenance lawns and high-traffic areas.

Because of its toughness, bahiagrass is frequently planted by our very own S.C. Department of Transportation to stabilize slopes when highway construction projects are completed between March and August. The colloquial name “highway grass” reflects this, but bahiagrass gets its other common name from the Brazilian state of Bahia (which means “bay” in Spanish).

Bahiagrass, with proper management, can also produce a fair to good pasture or hay crop. On drought-prone, sandy soils with relative low fertility, it is more productive than other forages. Bahiagrass can also be grown in poorly drained or lightly shaded areas, where bermudagrass pasture will not thrive.

Homeowners often consider it a weed, especially when its ugly bahiagrass heads seem to appear from nowhere overnight. You mow the lawn, and those suckers seem to spring back again the very next day. Because of this, at the Extension office, we are often asked how to get rid of it. Let me just say that it is hard to control the “bad” grass without harming the “good” grass. So the best control is to just mow the grass more often. And when it pops back up, then mow it again.

However, if you just must have an answer on how to kill bahiagrass in the home lawn, there are products that you can safely use. You must select the correct one, depending on what type of turfgrass you have, so that you don’t accidentally kill your whole lawn in one fell swoop. For example, if you have a centipedegrass lawn, it is safe to use herbicide products containing the active ingredients sethoxydim, metsulfuron, or atrazine. Examples of these products, as well as how to control bahiagrass in other turfgrasses, vegetable gardens and landscape beds, are included in our fact sheet at the Clemson Extension Home and Garden Information Center at https://hgic.clemson.edu/factsheet/bahiagrass/.

When using any pesticide, including weed killers or herbicides, please remember the words of Tony Melton: “The label is the law!” So please read the pesticide label and follow it carefully, to protect yourself, your family, your pets and your neighbors.

Trish DeHond is the home horticulture agent and Master Gardener coordinator for Clemson Extension in Darlington and Florence counties. She can be reached by email at pdehond@clemson.edu