How To Kill Wild Onions Growing In Lawns And Gardens
Wild onions, Allium canadense, and wild garlic, Allium vineale, are winter perennial weeds that become a nuisance in lawns, landscapes and gardens. While both have thin, green, waxy leaves, those of wild garlic are round and hollow, while those of wild onion are flat and solid. They emerge in late fall from underground bulbs and grow through the winter and spring. Though the plants will die back during the summer, if not controlled, in late spring, aerial bulblets are formed that will disperse seeds, which will produce new plants the next fall. The underground bulbs can persist in the soil for several years as well. So. if not controlled, more and more onions will appear with every passing year.

Methods of Control

Hand Pulling
I usually don't recommend this method. Reason being, when attempting to pull wild onions out of the ground the leaves will usually break off, leaving the bulbs in the ground. For best results, dig them out with a thin trowel. In soft soils such as in a vegetable garden you might be able to pull the entire plant.

In lawns, wild onions and garlic can be mowed, however this will not kill the plants. Regular mowing does however weaken plants and prevents them from setting and distributing seed.

Chemical Control in Lawns
Unfortunately, that I am aware of, there are no preemergence herbicides (weed preventers) that will control wild onion or wild garlic in lawns. So you'll have to spray them with a post emergent weed killer. The best herbicide I've found for killing wild onions and wild garlic in lawns is a liquid MSM herbicide, and I use a brand called Top Shot Weed Killer For Lawns. Top Shot is listed for use on most types of lawn grasses including Bermuda, Centipede, Turf-type Fescue, Kentucky Bluegrass, St. Augustine, and Zoysia. This product also kills many other types of grassy and broadleaf weeds.

Application: I usually just mix Top Shot up in a pump-type sprayer and spot treat, however a hose-ed sprayer can be used if your lawn is covered solid with onions, garlic and other weeds.

Timing of Spray: In lawns, spray wild onions and wild garlic in mid-fall and again in late winter or early spring, before plants can produce the next generation of bulbs.

Chemical Control in Landscape Beds

Glyphosate, the nonselective herbicide found in products such as Hi-Yield Killzall Super Concentrate 41%, can be used in landscape beds to kill wild garlic and wild onion to their roots...or bulbs in this case. "Nonselective herbicide" means that glyphosate will kill almost any type of plant it is sprayed on, including lawn grasses. So be very careful when using this chemical NOT to allow spray to drift on lawn grasses or desirable plants! When using any herbicide, always read and follow instructions for use on product label. I do NOT recommend spot-spraying any glyphosate-based product on lawns, even when the lawn appears to be dormant.

Application: When using 41% glyphosate to spray wild onions and wild garlic, I mix the solution a little stronger than normal at 3 ounces to one gallon of water in a pump-type sprayer.

Timing of Spray: Because the skin of wild onion and garlic plants thickens as the plants mature, I recommend spraying plants as soon after they emerge as possible, when plants are young and tender the chemical will be more readily absorbed by the plants and carried to the roots. Older plants might require two sprayings to effectively kill wild onion and garlic plants.

TIP: To avoid drift of spray, adjust the nozzle on your sprayer so that it is spraying more of a stream or shower than a fog or mist.

Hope this article was helpful and you get control of those wild onions!