Wild garlic and wild onion are two of the most frustrating cool-season weeds homeowners have to deal with in Georgia. Both of these weeds are closely-related and difficult to tell apart.
Wild garlic (Allium vineale) is by far the more common of the two. It has hollow leaves that are formed high on the stem. Wild garlic was introduced from Europe. It has a distinct garlic smell when disturbed. It can spread by seeds, and also by bulblets, which are tiny versions of the garlic plant. Wild onion (Allium canadense) is native to North America. It has a net-like covering over its bulbs, and its leaves are flat, not hollow, like those of wild garlic. Wild onions only produce seeds, not bulblets.
Both of these weeds are a nuisance in home landscapes because they produce large, unsightly clumps of green. These green clumps don’t look very good, especially on a dormant warm-season turfgrass during winter. Because of their ability to spread rapidly by seed and bulblet production, they can also easily become a problem in flower beds.
Both wild garlic and wild onion are related to plants in the Lily family such as Liriope and daylilies, according to Dr. Mark Czarnota, UGA Weed Specialist. This family has specialized characteristics that allow for the use of selective herbicides in turfgrasses without damaging the grass. If you choose not to use herbicides to control wild onion or wild garlic, it will be very difficult. The presence of underground bulbs, along with the delicate nature of their leaves, makes hand removal virtually impossible. Wild garlic produces so many small underground bulblets that even attempting to dig up and remove the plants would be futile.
Since wild onion and wild garlic re-sprout every year from bulbs, pre-emergence herbicides are not useful for control. Also, wild garlic bulbs will not always sprout in the same year, so 2-3 years of herbicidal use may be necessary for adequate control. Wild garlic and wild onion respond similarly to chemical controls, so treat them the same when applying herbicides.
Imazaquin and metsulfuron products work the best on wild garlic and onion in turfgrass areas. Two applications, one in January and one in March, have been shown by UGA research studies to give the highest percentage of control. These applications may have to be done for 2-3 consecutive years for total eradication. Imazaquin is sold under the trade name Image and metsulfuron is sold under various trade names such as Manor or Blade.
If you have garlic or onion issues in your landscape and flower beds, a nonselective herbicide like glyphosate (Roundup) is useful. Roundup will damage any plant that comes in contact with the spray, so a directed application to the weeds will aid in control. This will have to be a 2-3 year process for great control. I don’t recommend using Roundup on dormant turfgrass. Some people have had success with it, but it is often difficult to tell when the turf is emerging from winter dormancy, and Roundup will severely injure turfgrass.