Wild Onion / Wild Garlic: Kill, Control & Prevent It
Wild Onion and Wild Garlic are easily recognized from the garlic or onion odor of their crushed leaves. Some people confuse wild onion with a chive plant, an herb that looks very similar and also has an onion odor.
Wild garlic (Allium vineale) and wild onion (Allium canadense) are winter perennials, with wild garlic being predominant in North Carolina. They emerge in late fall from underground bulbs and grow through the winter and spring. In late spring, aerial bulblets are formed and the plants die back in early summer. The underground bulbs can persist in the soil for several years. While both have thin, green, waxy leaves, those of wild garlic are round and hollow, while those of wild onion are flat and solid.
Wild onion and wild garlic are very common lawn weeds. Fortunately, there are easy solutions for controlling them. With a small number of weeds, pulling, though difficult, is an option. It’s likely, however, that bulbs or bulblets will be left in the ground and new leaves will later re-emerge. For best results, dig them out with a thin trowel.
Unfortunately, there are no preemergence herbicides that will control wild onion or wild garlic. They must be treated with a postemergence herbicide, and persistence is the key. Plants will need to be sprayed more than once and for more than one season. One characteristic that makes control difficult is that both have a thin, glossy leaf to which herbicides don’t readily adhere. Unlike most weeds, mowing wild garlic or wild onion immediately before applying an herbicide may improve uptake. After application, do not mow for at least two weeks.
Treat wild garlic and wild onion in November and again in late winter or early spring before these plants can produce the next generation of bulbs in March. However, be careful not to apply most weed killers onto centipedegrass or St. Augustinegrass during their spring green up period. Inspect the lawn again in the spring and the next fall, and treat if necessary.
Recommended herbicides include Imazaquin, the active ingredient in Image Nutsedge Killer, and will provide control for wild garlic and wild onion. This product should not be used on fescue and should not be applied to warm season turf during green up in spring. Wait at least 1-½ months after treatment before reseeding, winter overseeding or plugging lawns. This product is not for use on newly planted lawns, nor on winter over-seeded lawns with annual ryegrass.
Three-way broadleaf herbicides containing 2,4-D, dicamba and mecoprop (MCPP) will provide control of wild garlic and wild onion with repeat applications. Examples of these products are Bayer Advanced Southern Weed Killer for Lawns, Spectracide Weed Stop for Lawns – for Southern Lawns, Lilly Miller Lawn Weed Killer, Southern Ag Lawn Weed Killer with Trimec®, and Ferti-lome Weed-Out Lawn Weed Killer. These products can be used safely on most turfgrasses, but reduced rates are recommended when applying to St. Augustinegrass or centipedegrass. Apply during November, very early spring, and again the next November for best control. Do not apply these herbicides during the spring green up of warm season turfgrasses, or over the root zone of nearby ornamental trees and shrubs. Do not apply these products to newly seeded grasses until well established (after the third mowing). Treated areas may be reseeded three to four weeks after application. Always check the product label for rate of application and to determine that it is safe for use on your species of turfgrass.
Glyphosate, the nonselective herbicide found in Roundup Original, Eraser Systemic Weed & Grass Killer, Quick Kill Grass & Weed Killer, Bonide Kleenup Grass & Weed Killer, Hi-Yield Super Concentrate Killzall Weed & Grass, Maxide Super Concentrate 41% Weed & Grass Killer, and Southern States Grass & Weed Killer Concentrate, will also provide control of wild garlic and wild onion. If you only have them in a couple different areas in the lawn, spot treat them with Ortho® Weed-B-Gon® MAX® Weed Killer for Lawns Ready-to-Use. If you are unable to prevent glyphosate from getting on desired, actively-growing grasses, a selective herbicide should be used. To avoid harming turfgrass, apply glyphosate only to warm- season grasses in winter, when they are completely dormant.
Around trees and shrubs and in flowerbeds, spot-treat with Roundup® Ready-to-Use Weed & Grass Killer Plus. Shield surrounding foliage and desirable plants when using this product and avoid applying it in windy conditions.
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Brenda Larson is the Horticulture Agent for North Carolina Cooperative Extension in Lee County.