Nutgrass, a perennial weed known as nutsedge, is a common and highly persistent invader in lawns and garden beds. Unlike true grasses, this plant is a sedge, making it resistant to many typical broadleaf weed killers. Its vigorous growth and ability to rapidly colonize an area often frustrate those attempting traditional removal methods. Effective control requires a multi-pronged approach that targets the plant’s unique biology. This guide explores proven, non-chemical strategies for eradicating this tenacious weed from your landscape.
Identifying Nutgrass and Its Underground Network
Proper identification is the first step toward effective control, since nutgrass behaves differently than common lawn weeds. The easiest identifying feature is the plant’s stem, which is solid and triangular in cross-section, leading to the adage, “sedges have edges.” True grass stems, in contrast, are hollow and round. The leaves are typically shinier, stiffer, and a lighter, yellowish-green color than surrounding turf, growing in sets of three from the base.
The key to nutgrass’s persistence lies in its extensive underground system of rhizomes and tubers, often called “nutlets.” These starchy storage organs anchor the plant and serve as its primary means of reproduction. A single plant can produce hundreds, or even thousands, of these tubers in a single season. If you simply pull the visible plant, the foliage breaks off, leaving the tubers and rhizomes intact beneath the soil to quickly sprout new growth. This network can reach up to 18 inches deep, protecting the nutlets and requiring natural methods that deplete this energy reserve.
Physical Removal and Smothering Techniques
Physical control methods are the most direct way to attack the nutgrass infestation, but they must precisely target the entire underground structure. For small, isolated patches, manual removal requires digging deep enough to extract the entire tuber chain, not just pulling the visible stems. Using a garden trowel or spade, carefully excavate the soil to a depth of at least 8 to 10 inches to retrieve all connected rhizomes and nutlets. This task demands persistence, as any remaining tubers can quickly resprout, requiring consistent follow-up.
For larger, unplanted areas, soil solarization utilizes the sun’s energy to heat the soil to temperatures lethal to the underground tubers. This process involves thoroughly wetting the infested soil, then covering the area tightly with clear plastic sheeting. The clear plastic, rather than black, creates a greenhouse effect that traps solar radiation and raises the soil temperature significantly. The edges of the plastic must be anchored securely with soil or weights to seal in the heat.
Solarization is most effective during the hottest months and requires the plastic to remain in place for a minimum of four to six weeks. This extended period of high heat effectively kills the nutlets and weed seeds in the upper soil layer, sterilizing the area for future planting. A less intense, but still effective, method is smothering, which uses opaque materials like thick layers of cardboard or black plastic to completely block sunlight. This light deprivation starves the plants, forcing the tubers to expend their stored energy. Smothering requires keeping the area covered for an extended period, often several months, to fully deplete the nutlet energy reserves.
Adjusting the Environment for Long-Term Control
Addressing the environmental conditions that favor nutgrass growth is a foundational strategy for long-term control. Nutgrass thrives in poorly drained, consistently moist soils, often outcompeting turfgrass. Adjusting irrigation practices to provide deep, infrequent watering encourages the growth of deep-rooted, desired plants. This simultaneously reduces the surface moisture that nutgrass prefers.
Improving soil health and drainage creates a less hospitable environment for the weed. Compacted soils retain water near the surface, so practices like core or liquid aeration improve the movement of water and air through the soil profile. Better drainage reduces the standing water that allows nutgrass to establish a foothold.
Encouraging a dense, healthy stand of grass or groundcover is an effective form of competition. When desirable plants are thick and tall, they shade the soil surface, inhibiting the germination of new nutgrass seedlings and reducing the vigor of established plants. Mowing turf at a higher setting contributes to a denser canopy that physically suppresses weed growth. Applying a thick layer of organic mulch, such as wood chips or straw, in garden beds helps to block sunlight and prevent new nutgrass shoots from emerging.
Homemade Solutions for Foliage Kill
While cultural and physical methods target the root of the problem, homemade topical sprays offer an immediate, natural way to burn back the visible foliage. Horticultural vinegar, which has an acetic acid concentration of 10% to 20%, acts as a non-selective contact herbicide. When sprayed directly onto the leaves, the high acidity rapidly desiccates the plant tissue, causing the top growth to collapse.
These solutions only kill the part of the plant above ground and do not penetrate the soil to reach the tubers. Because of the rapid foliage kill, the plant is signaled to send up new shoots from the unaffected underground nutlets. Therefore, repeated application every two to three weeks is necessary. For enhanced efficacy, some gardeners mix a small amount of liquid dish soap with the vinegar; the soap acts as a surfactant to help the solution stick to the waxy leaves. Always use caution with concentrated vinegar and avoid spraying on a windy day to protect nearby desirable plants, as it will damage any foliage it contacts.