Wild garlic (Allium vineale), commonly called onion grass, is a pervasive, cool-season perennial weed known for its difficulty in elimination. This plant emerges from underground bulbs in the fall, growing actively through winter and spring, which allows it to thrive when most turfgrasses are dormant. Its resilience comes from its reproductive strategy, which involves both underground bulbs and aerial bulblets that can persist in the soil for several years. Furthermore, the leaves have a thin, waxy coating, or cuticle, which makes it challenging for herbicides to stick to and penetrate the plant tissue. Successfully removing this weed requires persistence and a multi-year control plan that targets both the foliage and the underground structures.
Identifying the Weed
Effective control begins with accurately identifying the specific species present, typically wild garlic (Allium vineale) or wild onion (Allium canadense). Both plants are thin, green, and waxy, and they produce a distinct oniony or garlicky odor when their foliage is crushed. The primary difference lies in the structure of their leaves. Wild garlic leaves are round, smooth, and hollow, much like a thin straw or chive. In contrast, the leaves of wild onion are flat and solid, emerging from the base of the plant. Wild garlic is considered the more common and troublesome weed of the two.
Manual and Organic Removal Strategies
Manual removal is practical for smaller infestations and offers a completely chemical-free approach. Success depends entirely on removing the entire bulb system, since fragments left behind can sprout new plants. Dig out the plants in early spring or late fall when they are actively growing but have not yet produced new bulblets. Using a thin trowel or garden fork to loosen moist soil makes it easier to pull out the entire clump, including the underground bulbs.
After digging, dispose of the removed plants in the trash or green waste, as composting may allow bulbs to survive and spread. For dense patches in garden beds, fall tillage can help reduce infestations by disturbing the soil and exposing the bulbs.
Smothering is another non-chemical option for heavily infested areas. This involves covering the area with heavy mulch or black plastic to block all sunlight. This starves the underground bulbs, but it requires several weeks or months to be fully effective.
Promoting a dense, healthy turf suppresses the weed by limiting space and sunlight. While mowing will not kill the weed, regular clipping prevents the production of aerial bulblets that spread the weed. For persistent infestations, repeated manual removal over two to three seasons significantly reduces the population.
Chemical Treatment Options
Chemical control is often necessary for large infestations, but the waxy coating requires specialized application techniques. Systemic post-emergence herbicides are required because they are absorbed by the foliage and translocated down to the bulbs. For turfgrass, herbicides containing synthetic auxins, such as 2,4-D, dicamba, and mecoprop, are commonly recommended. Other effective chemicals include metsulfuron, imazaquin, and sulfosulfuron.
Timing is paramount, as the herbicide must be applied when the plant is actively transferring energy to its underground storage organs in late fall and again in early spring. Applying the herbicide during these cooler periods maximizes effectiveness before the plants produce aerial bulblets. To improve adhesion and penetration, adding a non-ionic surfactant to the mixture is highly recommended. Mowing or bruising the leaves immediately before application can also improve chemical uptake.
For non-turf areas, a non-selective herbicide like glyphosate can be used for spot treatment, though it will kill any plant it contacts. Multiple applications over a minimum of two to three years are typically needed to exhaust the dormant bulbs. After treatment, delay mowing for at least ten to fourteen days to allow the chemical sufficient time to move throughout the plant and reach the bulbs.