Herbicides

• Onion grass can be controlled with the proper herbicide. The herbicide must be chosen and applied carefully, however, or you risk losing your lawn, as well. Read labels thoroughly to be certain that the chemical will treat the wild onion. Treating with chemicals usually requires double treatment in the fall of the year when perennials are tender, and subsequent treatments in the spring when new growth appears and again the following year. Spring and autumn treatments should be done approximately six weeks apart.
  
  

Direct Application

• When the health of the grass is a concern, it is possible to treat onion grass specifically, and avoid getting the chemical on nearby plants. This is most easily done early on when onion grass populations are just beginning. The plant's leaves have a waxy coating that makes it difficult for herbicides to penetrate, so use gloves and a rough-textured sponge soaked in your chosen chemical to repeatedly rub the leaves of the onion plant. Start at the ground and sweep to the end of the leaf. You may also attach the sponge to cooking tongs with rubber bands and use them instead of your hands; it is still advisable to wear gloves. Repeat the process at the same frequency as spraying.
  
  

Sod Removal

• If the onions are infesting sod, and especially newly laid sod, sometimes it becomes necessary to remove the sod in the infested area. The top layer of soil must be removed from beneath the sod, as well, in case any bulblets have taken root there. When all affected soil has been cleaned away, replace with new soil and sod to solve the problem.
  
  

Healthy Lawns

• Preventing onion grass is by far the easiest way to control it. A healthy lawn that is fed, sown and mowed at regular intervals will not invite intruders such as onion grass and other weeds. Onion grass generally begins in areas that are bare or where the grass is otherwise stressed.