Wild garlic & wild onion

Wild garlic (Allium vineale) and wild onion (Allium canadense) are perennial weeds that emerge as upright clumps of slender, grass-like leaves that stand taller than the surrounding turf and emit a distinct onion or garlic odor when crushed, the surest field test. The two are separated by their leaves: wild garlic has round, hollow leaves, while wild onion has flat, solid leaves. Both arise from underground bulbs, and wild garlic in particular produces offset bulblets around the parent bulb and, in late spring, clusters of small aerial bulblets at the top of the flower stalk. The clumping, upright, fast-growing tufts that rise above a freshly mown lawn, combined with the onion-garlic smell, distinguish them from true grasses and from other clumping weeds.

Wild garlic and wild onion mar turf appearance by producing fast-growing, upright clumps of slender leaves that shoot above the mown lawn surface within days of cutting, creating an uneven, tufted, ragged look. Their dark green clumps contrast with dormant or slower-growing turf in winter and early spring, and the strong onion-garlic odor released during mowing is objectionable. While they do not form smothering mats, the persistent clumps disrupt the uniform texture and color of the stand and are a recurring nuisance because they regrow from bulbs each cool season.

Wild garlic and wild onion are cool-season perennials that grow from underground bulbs which can lie dormant and persist in the soil for several years before sprouting, making complete control a multi-year effort. They emerge in late fall, grow through winter and spring, and die back in early summer as the soil warms. They reproduce by underground bulbs and bulblets and, in wild garlic, by aerial bulblets formed at the top of the seedstalk; the hard, dormant bulblets germinate over different seasons, so a single treatment rarely catches the entire population.

These Allium weeds are widespread across the eastern and central United States and are favored by their winter-active growth habit, which lets them flourish during the cool months when cool-season turf is less competitive and warm-season turf is dormant. They invade lawns, pastures, roadsides, and turf of all kinds, and their persistent soil bulb bank means infestations recur year after year from the same area. Because they green up and grow tall during fall through spring, they are most conspicuous and most damaging during those cool-weather periods.