Nutsedge, often mistakenly called nutgrass, is a perennial weed that challenges lawn owners. It is a member of the sedge family, not a true grass, which is why conventional broadleaf or grassy weed killers are ineffective. Selective control requires specific, targeted solutions to eliminate the intruder without harming the turfgrass. Understanding the plant’s unique biology is the first step toward effective removal.
Why Nutsedge is Difficult to Control
The difficulty in controlling nutsedge stems from its distinct anatomy and reproductive method. Unlike grasses with round stems, nutsedge plants possess a solid, triangular stem, a defining characteristic of the sedge family. This unique structure and its waxy leaf surface limit the absorption and translocation of many standard herbicides.
The plant’s underground reproductive strategy is the greatest obstacle to successful eradication. Nutsedge produces hard, starchy tubers, called nutlets, on its rhizomes that can remain dormant for several seasons. A single plant can produce hundreds of nutlets, often buried 8 to 14 inches deep. When the above-ground foliage is damaged, these nutlets quickly sprout new shoots, making simple hand-pulling or contact herbicides ineffective for long-term control.
Selective Herbicides That Spare Grass
Nutsedge requires herbicides with specific active ingredients (AIs) that selectively target the sedge family. The most effective solutions are systemic herbicides that are absorbed by the foliage and translocated down to the underground tubers. This action is necessary to kill the entire plant structure, including the dormant nutlets.
Halosulfuron-methyl is a widely used and effective AI for nutsedge control in turfgrass. This chemical inhibits the acetolactate synthase (ALS) enzyme, preventing the biosynthesis of essential amino acids. Turfgrass is tolerant because it can rapidly metabolize and inactivate the chemical, while nutsedge cannot, leading to the cessation of cell division and eventual death.
Another selective AI is Sulfentrazone, effective against yellow nutsedge and providing suppression of purple nutsedge. Sulfentrazone is a protoporphyrinogen oxidase (PPO) inhibitor, disrupting the weed’s cell membranes and causing rapid necrosis when exposed to light. It works as both a post-emergent and a residual pre-emergent treatment, often providing control for up to 60 days by disrupting new sprouts.
Bentazon is sometimes used for nutsedge but is considered a contact herbicide, primarily burning down the foliage it touches. While it provides a quick visual result, it does not translocate effectively to the underground tubers, necessitating repeat applications to exhaust the nutlet’s energy reserves. When selecting a product, check the label for compatibility with specific turfgrass types, as some warm-season grasses may be sensitive to certain formulations.
Non-Chemical and Cultural Control Methods
Cultural and non-chemical methods can significantly reduce nutsedge populations, supplementing chemical control or serving as alternatives. Nutsedge is an indicator plant, often signaling underlying issues like poorly drained or compacted soil. Addressing these conditions is the first step in cultural control.
Adjusting irrigation practices is highly effective, since nutsedge thrives in overly moist environments. Allowing the soil surface to dry out between waterings makes the area less hospitable and encourages healthier turfgrass growth. Raising the mower height to the highest recommended setting helps shade the soil surface. This canopy density suppresses nutsedge growth, which prefers full sun, and strengthens the turf to out-compete the weed.
Manual removal is labor-intensive and must be executed with precision. Simply pulling the plant can cause rhizomes to break, stimulating dormant nutlets to sprout new plants. Effective manual control requires carefully digging deep with a trowel to remove the entire plant and its attached nutlets, which can be 6 to 12 inches below the surface. For severely infested small areas, solarization—covering the area with clear plastic sheeting during hot weather—can be used to heat the soil and kill the nutlets.
Maximizing Effectiveness and Preventing Recurrence
Achieving long-term nutsedge control requires a strategic approach combining the right products with proper timing and cultural practices. The most successful chemical applications occur when the nutsedge is young and actively growing, typically in late spring or early summer, before it produces new nutlets. Targeting the plant when it has four to six leaves maximizes the herbicide’s ability to translocate the chemical down to the developing tubers.
A single application is rarely sufficient due to the staggered germination of nutlets. A follow-up application is usually necessary four to six weeks after the initial treatment to control new shoots. Adhering strictly to the product label’s instructions regarding application rates and water volume is paramount, as proper coverage ensures the herbicide reaches the foliage for maximum absorption.
Maintaining a dense, healthy lawn is the final step in preventing nutsedge recurrence. This involves proper fertilization, aeration to relieve soil compaction, and consistent deep, infrequent watering. A vigorous stand of turfgrass naturally out-competes nutsedge by monopolizing sunlight, water, and nutrients, creating an environment where the weed cannot establish itself.