Quackgrass (Elymus repens) is one of the most challenging perennial weeds to manage in a lawn setting. Its aggressive growth habit makes it difficult to control once established in turfgrass. Effective removal requires a strategic and persistent approach, often combining cultural, physical, and chemical methods.
Identifying the Invasive Grass
The first step in controlling this weed is accurately confirming its presence. Quackgrass is a coarse-textured, cool-season grass that often exhibits a distinct blue-green or ashy color, contrasting sharply with the finer texture and darker green of typical turfgrasses. If not regularly mowed, quackgrass frequently grows taller than the surrounding lawn, creating noticeable tufts or patches.
The most reliable way to identify quackgrass is by examining the junction where the leaf blade meets the stem. Look for a pair of small, claw-like appendages, called auricles, which clasp or wrap around the stem. This specific feature distinguishes it from many other common lawn grasses and weeds.
Understanding the Rhizome System
Quackgrass is difficult to eliminate because of its extensive rhizome system beneath the soil surface. Rhizomes are sharp-tipped, white or pale yellow underground stems that function as a carbohydrate storage network for the plant. These structures allow the plant to survive harsh conditions and quickly regenerate after the above-ground foliage is damaged.
A single quackgrass plant can produce hundreds of feet of rhizomes in a dense mat, typically concentrated within the top six inches of the soil. Each rhizome segment contains multiple nodes, and even a small fragment can sprout into a completely new, vigorous plant. Disturbing the soil through tilling or digging can inadvertently chop these rhizomes into pieces, activating dormant buds and multiplying the infestation.
Non-Chemical Eradication Strategies
For small, isolated patches, manual removal can be effective, provided it is done with extreme diligence. Moisten the soil around the patch to make the entire root network easier to extract without breakage. Using a weeding fork or narrow trowel, carefully dig down and lift out the entire clump, ensuring every piece of the white rhizome is removed from the soil. All pulled plant material must be bagged and discarded, as composting will likely allow the fragments to re-root and spread.
Solarization is an effective non-chemical technique for larger, contained areas that can be sacrificed temporarily. This method involves covering the infested area with clear plastic sheeting during the hottest part of the summer. The plastic traps solar energy, raising the soil temperature high enough to kill the rhizomes and seeds over six to eight weeks.
Cultural controls that favor the desired turfgrass are another non-chemical approach. Maintaining a dense, healthy lawn by fertilizing and overseeding helps the turfgrass outcompete the quackgrass shoots. Mowing your lawn at a higher height (2.5 to 3 inches) helps shade the soil, which discourages the growth of new quackgrass shoots.
Targeted Chemical Control
Chemical control remains the most reliable method for managing widespread or severe quackgrass infestations. Non-selective systemic herbicides, such as those containing glyphosate, are the most effective chemical option. These herbicides are absorbed by the leaves and translocated throughout the plant, including the extensive rhizome network, to achieve a complete kill.
Since non-selective products kill any plant they contact, they must be applied carefully as a spot treatment directly onto the quackgrass patches. For heavy infestations, the most practical method is to kill the entire patch, including the desirable turf, and then reseed or resod the treated area after a sufficient waiting period. Due to the high energy reserves in the rhizomes, a single application is rarely sufficient; a second treatment 7 to 14 days later is often necessary to kill any surviving shoots.
For certain turf types, some grass-selective herbicides (e.g., sethoxydim or fluazifop) may offer a degree of suppression. However, these products are often formulated for use over broadleaf crops and may not be safe for use over all types of turfgrass. Always read the product label carefully to confirm the herbicide is safe for your specific lawn type and to understand the required safety precautions.
Preventing Future Infestations
Long-term success depends on prevention and maintaining turf health to discourage re-establishment. A dense, vigorous lawn is the best natural defense because it shades the soil and physically crowds out new weed seedlings and rhizome sprouts. This density is achieved through a consistent program of proper fertilization, aeration, and regular overseeding with high-quality turfgrass varieties.
Lawn care also includes ensuring that any soil, mulch, or sod brought into the area is certified as weed-free to prevent the introduction of new seeds or rhizome fragments. Where quackgrass is encroaching from an adjacent area, installing a physical barrier, like deep landscape edging, can help block the creeping rhizomes. Since quackgrass thrives in disturbed soil, minimizing tilling or digging in infested areas also limits the spread of rhizome fragments.