Things You'll Need
Tank or hose-end sprayer
Lawn weeds are sometimes a challenge to control. It is difficult to find herbicides to kill the weed without also killing the grass. When determining which herbicide to purchase to kill wild onion in your grass, read the labels carefully so that you apply the right product for your type of turfgrass. Choose a November day with little wind on which to apply the herbicide, so that the herbicide doesn't drift onto your desirable landscape plants.
Mow the wild onion. This will allow the herbicide to better penetrate the foliage, according to horticulture extension agents with Clemson University.
Pour the herbicide into the tank portion of the sprayer. Use the amount specified on the label. Add water at the rate recommended by the herbicide manufacturer. Replace the cover on the tank.
Spray the herbicide over the wild onion plants until they are completely saturated with the product.
Wait one day after application and then water the area that you treated.
Reapply the herbicide, in the same manner, in spring, and again in November. You may need to repeat the process the following spring. The timing of this spraying cycle, according to the Clemson Cooperative Extension website, will keep wild onions from producing their next generation of bulbs.
Wait two weeks after application to mow the lawn.
Look for herbicides containing Imazaquin or 2,4-D for control of wild onion. These chemicals are not safe on all grasses. If you have any questions as to the safety of these chemicals for your type of turfgrass, contact your county cooperative extension office for advice.
Don’t mow the lawn again for the first two weeks after applying the herbicide. Herbicides may contain toxic chemicals. Read and follow all label directions and cautions wear protective clothing, including a breathing mask during application.