Wild onions sprout in yards during late winter or early spring. Along with the closely related wild garlic, wild spring onions are easily identifiable by their distinctive aromas. If your yard smells like the produce section of a grocery store, you likely have wild spring onions growing. Although wild spring onions are edible, your yard will look better if you kill them off. You can kill wild onions and wild garlic with the same procedures, as you might have both growing next to each other in your lawn.
Mow your lawn to prepare for herbicide application. Choose a still day in November to spray the herbicide.
Mix the herbicide in the garden sprayer according to the package directions. Choose a three-way herbicide containing 2,4D, dicamba and mecoprop.
Spray the area of your lawn where the wild spring onions are growing, following the herbicide application directions, to prevent future growth of the plants. Wait for two weeks before mowing your lawn again.
Repeat the spraying in early spring, then again one year after the first application. Continue on this schedule until the wild spring onions are eradicated.
Dig up the wild spring onions with a trowel if there are only a handful growing in the lawn. Check the herbicide label to be sure it is safe for use with your type of turf grass.