Nutsedge is a perennial weed that poses a unique challenge in lawn care because it is often mistaken for a grass. This confusion leads many homeowners to treat it with standard broadleaf weed killers, which are ineffective. Because nutsedge is botanically a sedge, a distinct plant family, it requires specialized treatment to selectively eliminate it without damaging the surrounding turfgrass. The solution involves understanding the plant’s biology and employing targeted chemical and cultural control methods.
Identifying Nutsedge Versus Grass
Nutsedge, often incorrectly called “nutgrass,” belongs to the Cyperaceae family, while true grasses belong to the Poaceae family. This difference means the internal structure of nutsedge is fundamentally different from turfgrass, explaining why broadleaf herbicides do not work. The most reliable way to identify nutsedge is by examining the stem: nutsedge has a solid, triangular stem, while turfgrass stems are round and hollow.
The leaves of nutsedge grow in a distinctive three-ranked arrangement, spiraling around the triangular stem, in contrast to the two-ranked arrangement found in grasses. Nutsedge foliage typically presents a brighter, yellowish-green color that grows noticeably faster and taller than the surrounding turf after mowing. It spreads primarily through underground tubers called nutlets, which can survive in the soil for several years.
Selective Herbicides That Target Nutsedge
Controlling nutsedge without harming the lawn depends on using selective herbicides formulated to target sedges specifically. These chemicals work by exploiting the metabolic differences between sedges and turfgrass, allowing the grass to remain unharmed. The two most effective active ingredients for selective nutsedge control are Halosulfuron-methyl and Sulfentrazone.
Halosulfuron-methyl is a systemic herbicide absorbed through the foliage and translocated throughout the plant, including down to the underground nutlets. This systemic action disrupts the plant’s growth processes and prevents the nutlets from sprouting new plants. Products containing this ingredient are effective against both yellow and purple nutsedge species.
Sulfentrazone is another selective herbicide that provides faster visible results, often causing injury symptoms within a few days of application. This chemical is frequently combined with other active ingredients to offer broad-spectrum weed control. Both Halosulfuron-methyl and Sulfentrazone are designed to be safely applied over most established turfgrass varieties, but check the product label for specific turfgrass tolerances before application.
Cultural Practices for Management
Chemical treatments are more effective when complemented by cultural practices that eliminate the environmental conditions nutsedge prefers. Nutsedge thrives in moist, poorly drained, and compacted soil. Improving soil health is a long-term management strategy. Reducing irrigation frequency and ensuring water is not pooling in low-lying areas will make the environment less hospitable for the weed.
A change in mowing height can help suppress nutsedge growth by increasing competition from the turfgrass. Raising the cutting height allows the turf blades to grow taller and denser, shading the soil surface. This canopy reduces the sunlight reaching new nutsedge sprouts, slowing their growth and preventing them from establishing a strong foothold. Annual core aeration can relieve soil compaction, which improves internal drainage and allows turfgrass roots to grow deeper and outcompete the nutsedge.
Attempting to hand-pull nutsedge is generally ineffective and can often worsen the problem. When the visible shoot is pulled, the underground nutlets frequently remain in the soil and are stimulated to sprout new plants, sometimes multiplying the infestation. Physical removal should only be attempted on small, isolated plants by carefully digging out the entire plant and surrounding soil to ensure all nutlets are removed.
The Best Time and Method for Application
The timing of herbicide application is important for achieving successful nutsedge control. Selective herbicides should be applied early in the growing season, typically late spring or early summer, when the nutsedge is young and actively growing. Treating the weed at this stage is most effective because the plant has not yet begun to form a significant number of new nutlets, which are the primary source of regrowth.
Application must be done when the nutsedge foliage is dry so the herbicide can be properly absorbed. Because the life cycle of nutsedge includes the dormancy of nutlets, a single application rarely provides complete eradication. A follow-up application is usually necessary, spaced 10 to 14 days after the initial treatment, to eliminate any new sprouts.
Spot treatment is effective for small, localized infestations. For larger, widespread infestations, a broadcast application is necessary. Avoid mowing for at least two days before and after application. This interval ensures there is sufficient leaf surface to absorb the systemic herbicide and allows the chemical time to translocate down to the nutlets before the foliage is cut.