How To Get Rid Of Onion Grass In Your Lawn

Growing onions is excellent, but having them flourish in your pristine lawn is not. While you might be okay with the wild onion grass taking root in specific areas of your garden, you probably don’t want it thriving on your lawn. So, how do you remove it?

This article walks you through onion grass and how to remove it, so continue reading to learn more!

What Is Onion Grass?

Onion grass (Allium canadense) is a cool-season perennial weed that flourishes in acidic soil. Unfortunately for your lawn, it spreads quickly by reseeding and reproducing under the soil, so it might rapidly multiply before you even realize it’s a problem.

Onion grass manages to thrive year-round, as it stores food in the bulb of the grass, allowing it to live through the winter months. Because of its rapid reproduction rate and hardiness (even in cooler temperatures), it can be tricky to get rid of onion grass. 

Every year, new sprouts appear from the reproduced underground bulbs hiding within the soil, creating a problem that multiplies exponentially. 

How Do You Identify Onion Grass?

Identifying onion grass is easy – the leaves are thin, waxy, and spear-shaped, and the bulbs at the base of the grass are white. If you break a piece of one of the leaves, it will smell just like an onion (hence the name). 

You might realize you have onion grass flourishing when you’re mowing and smell a waft of onions. It’s confusing at first, but you can tackle the problem once you find the weed.

Wild garlic is another common plant that might invade your lawn, although onion grass tends to be more prevalent. Neither one are harmful to your yard, although they disrupt the even appearance of the grass since they grow much taller than most grasses. 

Wild onions and garlic are edible, but you must identify them correctly. Death Camus looks remarkably similar to wild onion in numerous ways, although it doesn’t share the same pungent smell. So, while you could eat them, we don’t recommend it unless you’re positive that you’re dealing with wild onion. 

How Do You Get Rid Of Onion Grass Permanently?

There are a few different ways to approach an onion grass invasion, some of which are easier than others. Here are a few ways to tackle the problem:

Dig Them Up

One way to remove the plant is by manually digging them up. If you choose to go this route, make sure you remove the entire plant. Otherwise, you’ll be back to square one within a few weeks. 

If there are only a few onion grass plants poking up here and there, this is an excellent approach. Water the area or wait until a few hours after heavy rain, which will soften the ground and make removal easier. 

The bulbs extend considerably deeper into the soil than most grasses, so you’ll need to dig about 6 inches deep. Using a small shovel or a trowel, dig into the ground to the side of the plant. Once you loosen the plant, remove it in its entirety. 

Be sure you remove the entire bulb, stalk, and root, as leaving any parts behind will result in new onion grass. 

Use An Herbicide

Hand-pulling the plants isn’t ideal when dozens of them are across your yard. In this case, consider using an herbicide. Use a non-selective herbicide to kill the plant, but remember, you’ll probably kill a patch of the surrounding grass as well. 

For a more precise application, lay a flattened cardboard box around the plant. This will help protect the grass around the plant from overspray, ensuring you don’t accidentally kill more plants than you were trying to. 

When you choose an herbicide, make sure you note whether it’s safe for dogs and children. If not, keep your kids and animals off the lawn while the product does its work. 

Follow Up With Glyphosate

Killzall Weed and Grass Killer - 41% Glyphosate

Glyphosate is another option to eliminate the onion grass crowding your lawn. After you pull up the plants, you can apply this to the area where the plant was. This will help eradicate any seedlings that are left over. 

You can also use this on the plants – after you apply it, wait three days, then check to see if the grass is wilting. If it’s still standing tall, you might have to reapply several times, waiting a few days between applications. 

For best results, follow the manufacturer’s instructions on the packaging label. You need to apply the plant killer to the affected areas on a warm, sunny day. Remember, like many herbicides, glyphosate can kill the surrounding plants, including grasses and flowers. 

How Do You Get Rid Of Onion Grass Naturally?

If you’re not too keen on using toxic chemicals to kill the onion grass invading your lawn, consider a more natural approach to the problem. Vinegar and boiling water are natural methods for killing onion grass. 

To kill the grass with vinegar, simply apply a large dose to the plant, allowing it to soak into the soil around the onion grass. 

Or, if you don’t have vinegar on hand, use hot water. Boil a pot of water, then pour it on the plant. Remember, the intense heat of the water will kill the surrounding plants, so you might have a bare patch of grass there.