Wild onion and wild garlic are different plants with similar characteristics. Both grow in grass-like clumps of tall, smooth leaves topped with white or purple flowers appearing in early summer. Wild garlic stems are hollow while wild onion stems are not, while both have the characteristic onion smell. See botanical illustration.
Wild onion and wild garlic are perennials, spreading by means of bulbs and roots. Wild garlic may also produce small bulblets at its leaf tip which can fall off and take root and sprout. Both wild onion and wild garlic green up in the early spring and grow vigorously early spring to mid-summer.
Mow low in the early spring to reduce potential for infestation. Dig up bulbs by hand.
Spot spray in late fall or early spring with post-emergent broadleaf herbicide containing triclopyr, clopyralid, or 2,4-D, MCPP, and dicamba.