Yellow Nutsedge ID and Control in Home Gardens

Yellow nutsedge (Cyperus esculentus) is a perennial weed that invades lawns and landscape beds. This weed prefers a sunny location that is moist and nutrient-rich. It is also known as yellow nut-grass, chufa, nutsedge, watergrass, northern nut-grass, earth almond, rushnut, umbrella sedge, and galingale. The number of aliases is an indication of just how ubiquitous it is throughout North America.

Unlike most plants found in your lawn, it is neither a grass nor a broadleaf weed. Yellow nutsedge is, technically, a sedge, a member of the Cyperaceae family. Its classification is important for identification and eradication.

Recalling this botanical rhyme will help with the identification of this weed.

Sedges have edges

Rushes are round

Grasses have knees that bend to the ground

Yellow nutsedge is identified by its triangular (three-edged) stem. Leaves develop at the plant base in sets of three and form a sheath around the stem. Its leaves are shiny, hairless, long, and grass-like. They have a mid-rib and taper to a narrow tip.

As its name suggests, the leaves are a distinctive yellow-green (chartreuse). The color stands out against the deep green of turfgrass. The leaves grow quickly in the summer heat. Between mowing, yellow nutsedge becomes taller than the neighboring slower-growing cool-season grasses.

Yellow nutsedge emerges from underground tubers ("nutlets") in late spring after the soil has warmed, about the same time that crabgrass emerges. It grows actively throughout the summer, producing more underground tubers and spreading stems (rhizomes). Other tubers become above-ground plants. A single plant produces several hundred tubers throughout a good growing season.

While yellow nutsedge will produce seedheads, they are rarely seen in the regularly mown lawn. Seedheads are more likely to be found in yellow nutsedge in landscape beds. The seedheads are small, 0.5 to 1.25 inches long, and look like miniature bottlebrushes. They turn from yellow to brown as the seedheads mature. In truth, the seeds do not germinate as readily as do many annual weeds' seeds. This perennial's primary means of spreading is underground through its rhizomes and tubers. It usually is inadvertently transferred to your landscape with the transfer of soil containing yellow nutsedge tubers.

Photo credit: Howard F. Schwartz, Colorado State University, Bugwood.org

The leaves and the underground rhizomes of nutsedge die back with the first freeze. However, the tubers become dormant, overwinter, and remain viable in the soil for up to ten years.

Like all turfgrass weeds, maintaining a thick healthy lawn will help to keep this weed in check. If the patch is small, hand pull the emerging leaves early and often. While this won’t kill the tuber, it will reduce the strength of the underground structures, preventing the development of strong, new tubers. In landscape beds, dig up and remove all parts of the plant's underground system.

If chemical control is warranted, remember that this weed is a sedge. Many products formulated for killing weeds in turfgrass will eradicate broadleaf weeds and some grasses, but not this sedge. It is a difficult weed to control and may take several applications, perhaps for more than one season. Timing is important. The best time for applying an herbicide is during the active growing season in late spring or early summer. It is more susceptible to herbicides at that time. It is also before yellow nutsedge has had a whole season to create more tubers. Recommended herbicides include those that contain sulfentrazone or halosulfuron. Always follow the directions and cautions on the herbicide label, including the timing of applications. More is not better. For more information on controlling yellow nutsedge, please see Lawn and Turfgrass Weeds: Yellow Nutsedge.