Yellow nutsedge patch in lawn
Nutsedge is the yellowish bladed growth sticking up above the rest of the grass
George Weigel

For a plant that isn’t actually a grass, yellow nutsedge does a great job blending unnoticed into a lawn... until it’s patched its way through substantial areas of the yard.

What finally gives away this grass imposter is when lawn-owners notice patches of lighter-green – almost yellowish – blades sticking up above the rest of the lawn in summer. That’s when yellow nutsedge often regrows quicker than grass after a mowing and suddenly stands out like the proverbial sore thumb.

Nutsedge has a triangular stem
Nutsedge can be recognized by its yellowish color and triangular stems.
George Weigel

What is nutsedge and how did it get there?

Sometimes called nutgrass for its grassy look, nutsedge is really a weedy version of the sedge family that’s distinctive from true grass by its triangular stem. It shows up in lawns and garden beds in almost every U.S. state and is classified as a noxious weed in many of them.

Nutsedge grows from small bulbs called “nutlets” that form on the plant’s roots. Because nutsedge roots and nutlets can grow a foot or more deep in the soil, they continue to thrive in a summer drought and heat wave while surrounding lawn grass is going dormant.

That’s when nutsedge really starts to stand out.

Nutsedge usually enters a lawn on blown-in or carried-in seeds from nearby plants that have gone to seed. Once plants take hold, they spread by underground rhizomes and sprout new plants from the nutlets as well as unmowed seedheads. Nutsedge is also cold-hardy throughout the U.S., meaning the “mother” plants come back year after year, too. Although nutsedge prefers damp, poorly drained areas, it also grows in hot, dry areas.

Nutsedge "nutlet" & root
Nutlets form on the ends of nutsedge roots, which can grow a foot deep in the soil. Photo by George Weigel
George Weigel

What to do about nutsedge

If you catch an infestation early, the best solution is to remove the invading plants by hand – ideally using a screwdriver or similar long, sharp tool that helps you dig out the whole root system along with any nutlets. If you leave behind any bulblets, new plants can sprout later.

Two ways to discourage nutsedge are to cut the lawn high (cutting low gives nutsedge a competitive advantage) and core-aerating and top-dressing the lawn each fall to encourage better lawn drainage.