Yellow nutsedge is hard to control if you don’t catch it early
“I think there is nutsedge in my lawn. How do I get rid of it?”
— Bob Carville, Evanston
Yellow nutsedge is a common weed found in turf areas and is challenging to control. You can identify it by the triangular shape of its stems, with light green to yellowish leaves. Each leaf will be long with a taper to the tip. It becomes more visible now during the heat of summer, as the cool-season turf grows more slowly while the nutsedge is actively growing. It will continue growing until frost kills the foliage in fall.
It is a perennial plant that spreads by small underground tubers called nutlets that form at the end of rhizomes. Rhizomes are underground stems. A single nutsedge plant can produce hundreds of these nutlets over the course of summer while also spreading by rhizomes. Nutsedge will flower and produce seeds when not mowed, but the seeds generally do not germinate.
Yellow nutsedge will be the biggest problem in lawns that are under stress and thin because of poor maintenance practices, such as mowing too low. It thrives in areas where soil remains moist from overwatering or poor drainage, although one can also find it in well-drained areas. Nutsedge may come in with topsoil you use for grading.
The first step in controlling nutsedge, as well as other lawn weeds, is to use proper cultural techniques that encourage a healthy and dense stand of turf. You can have a big impact on your lawn’s health by mowing at 3 to 3.5 inches. I see many lawns that are mowed too short, which adds stress to the turf and creates opportunities for weeds to move in. There is no need to collect grass clippings. Leave them on the lawn to recycle nutrients.
You will likely need to use an herbicide to eradicate the nutsedge from your lawn. It is difficult to remove the tubers when pulling this weed by hand in the lawn, so it will keep growing back. It may be worth a try for a small infestation, providing you are able to keep up with the weeding as it continues to sprout.
It is much easier to manually remove nutsedge growing in a bed, as you can dig out the tubers. It is important to choose the correct herbicide to control nutsedge and plan to make multiple applications to completely eradicate it. The best time to control yellow nutsedge is when the plant is actively growing in late spring and early summer, before it has started producing tubers.
Purchase an herbicide that has either halosulfuron or sulfentrazone as an active ingredient to treat the nutsedge. It is best to use a surfactant with the halosulfuron to provide better coverage of the leaf surface. It is important to read the label of any herbicide you use and carefully follow directions.
The Chicago Botanic Garden has recently had success using a granular herbicide called Vexis to control nutsedge in lawns. The ideal window for controlling yellow nutsedge is closing quickly, as optimum control is achieved by applying herbicides prior to tuber production.
For more plant advice, contact the Plant Information Service at the Chicago Botanic Garden at plantinfo@chicagobotanic.org. Tim Johnson is senior director of horticulture at the Chicago Botanic Garden.
