How To Get Rid Of Onion Grass

How to Kill Wild Onion: close-up of a wild onion plant in the ground

Wild onion and wild garlic are cool-season perennial weeds that grow from underground bulbs. These weeds resemble green onions or chives, and are closely related to the garlic and onions that we grow in our gardens. Wild garlic and onion thrive in a variety of soil conditions, including heavy and wet soil, and are both cold- and drought-hardy.

Wild onion and wild garlic are easily recognized in the lawn by the strong garlic or onion odor they produce when mowed. Wild garlic has round, hollow leaves while wild onion produces flat, non-hollow leaves. They grow during the cooler parts of the year, so they usually don't appear in the lawn until the fall, when most other lawn weeds are dying back or preparing to go dormant for the winter. Wild onion and garlic will continue growing throughout the winter and spring. In late spring, if they are not mowed back, they will form aerial bulblets (smaller bulbs) that help the plants spread throughout your lawn. When it starts to get hot in early summer, the tops of wild garlic and onion will die back to the ground, and the bulbs will resprout again when the weather cools in the fall.

Here's how to get rid of wild onions and wild garlic in the lawn.

Don't Hand-Pull Wild Onion or Garlic

Wild onion and garlic are tricky if you try to hand-pull them. The bulblets are designed to pull away from the mother bulb when the plants are hand-pulled. So even if you pull up the main plant, there will be small bulbs left in the soil that will quickly grow back. If you only have a few clumps of wild onion or garlic in your lawn and you choose to remove them by hand, use a shovel or trowel to dig up the entire clump of bulbs, which can be at least 6 inches below the soil.

How to Kill Wild Onion and Garlic

How to Help Prevent Wild Onion and Garlic

The best way to combat future wild onion and garlic problems is to make it hard for them to grow in the first place. Keeping a well-fed, thick lawn will help keep wild garlic, wild onion, and other weeds out of your lawn because there will be no space for them to grow. It's worth noting, too, that having lots of weeds in your lawn is a sign that there's an issue with the overall health of your grass or soil (or both.) In addition to fertilizing, you may want to consider aerating or dethatching your lawn.