Wild Garlic & Wild Onion

Prepared by Chuck Burgess, HGIC Horticulture Extension Agent. Revised by Joey Williamson, HGIC Horticulture Extension Agent, Clemson University. (New 05/04. Revised 10/09. Images added 10/09.Pesticides updated 09/10.)

HGIC 2311

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Description

Wild garlic (Allium vineale) and wild onion (Allium canadense) are winter perennials, with wild garlic being predominant in South 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 garlic plants
Wild garlic plants.
Ohio State Weed Lab Archives, The Ohio State University, Bugwood.org

Control

Pulling: 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.

A cluster of wild garlic bulbs
A cluster of wild garlic bulbs.
Ohio State Weed Lab Archives, The Ohio State University, Bugwood.org

Mowing: Mowing will not kill wild garlic or wild onions. However regular mowing can weaken plants and prevent them from setting seed.

Chemical: 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.

Timing of Sprays: 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: Imazaquin, the active ingredient in Image Nutsedge Killer, 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 1-1/2 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.

Metsulfuron (Manor and Bladet) is a product packaged for landscape professionals. Due to the cost of this selective herbicide, it may be more economical to hire a landscape professional for weed treatment. Metsulfuron can be used on bermudagrass, St. Augustinegrass, centipedegrass, and zoysiagrass. The addition of a non-ionic surfactant (such as Southern Ag Surfactant for Herbicides) is required at 2 teaspoons per gallon of spray mix for best control. A non-ionic surfactant will help the herbicide adhere to the leaves for increased penetration. Do not apply metsulfuron to a lawn if over-seeded with annual ryegrass or over-seed for 8 weeks after application. Do not plant woody ornamentals in treated areas for one year after application of metsulfuron. Do not apply metsulfuron herbicides within two times the width of the drip line of desirable hardwood trees.

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 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.

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This information is supplied with the understanding that no discrimination is intended and no endorsement of brand names or registered trademarks by the Clemson University Cooperative Extension Service is implied, nor is any discrimination intended by the exclusion of products or manufacturers not named. All recommendations are for South Carolina conditions and may not apply to other areas. Use pesticides only according to the directions on the label. All recommendations for pesticide use are for South Carolina only and were legal at the time of publication, but the status of registration and use patterns are subject to change by action of state and federal regulatory agencies. Follow all directions, precautions and restrictions that are listed.