Annual tilling of garden plots provides sufficient control of wild onion for vegetable growers, but this plant causes serious problems for those who enjoy a well kept lawn. Thick clumps of wild onion bend beneath a mower's blades and lift up above the height of the surrounding grass when the mower passes. Different growth rates and different color make the wild onion clumps obvious and unpopular with homeowners. Without control, this invasive weed could dominate the yard.
Identify wild onion by the tall clusters of dark green slender leaves rising above the lawn and the distinctive onion smell of the crushed leaves. Wild onion emerges in late winter before grass begins to grow, making spotting the plant easy.
Remove clumps of wild onions by hand after the plants grow 6 to 8 inches tall. Press the blade of a garden trowel into the ground beside the clump and lever the plants loose. Grasp the cluster of leaves and pull up with steady pressure. Don't bend or twist the leaves and most of the onion bulbs should lift out of the ground without damaging the sod.
Patch any large pockmarks left by the missing clumps of onions by covering with good topsoil. Reseeding with grass should not be necessary, since a healthy lawn soon fills in small blemishes.
Inspect the area where wild onions grew before every mowing and dig or pull any straggler plants as soon as they show. Bulbs left behind may lie dormant for months before sprouting.
Spray clumps of wild onion with 2,4-D or triclopyr herbicide as an alternative to digging and pulling. Mix the chemicals according to label directions, and apply with a pump sprayer, being careful not to contaminate skin or clothing. Spray only the onion plants, not the entire area.