How to Get Rid of Onion Grass

Onion grass is a persistent weed that continues to pop up in the yard or garden year after year. It can spread quickly, make your yard look unkempt, and cause skin irritation and infections. Luckily, there are a number of things that you can do to eliminate them for good. In this guide, there are some steps you can take to get rid of onion grass.

What is onion grass and how do you recognize it?

Onion grass is a weed that can be found in yards and gardens. It has long, thin blades that look similar to those of an onion. The weeds can grow up to two feet tall and spread quickly.

Onion grass is a pernicious weed that is found in cool and moist environments. This invasive plant can spread rapidly. Its root will penetrate up to 6 inches of topsoil, thus making it very difficult to get rid of this pest. Luckily enough, it’s also susceptible to a variety of herbicides.

Onion grass may cause skin irritation or infection if it comes into contact with the skin.

What causes onion grass?

Onion grass is a weed that can be found in many gardens. It is identifiable by its long, thin leaves that resemble blades of grass. Onion grass thrives in moist environments, so it often pops up around garden edges and sidewalks.

While onion grass is not particularly harmful to plants or people, it can be difficult to get rid of once it takes hold.

Why do you need to get rid of onion grass?

There are a few reasons why you might want to get rid of onion grass. Some of which are:

  1. It can be an eyesore in your garden.
  2. If it grows unchecked, it can take over and choke out other plants.
  3. Onion grass is difficult to remove and can take some time and effort to eradicate completely.
  4. Makes lawn maintenance difficult.

How to get rid of onion grass

The best way to prevent onion grass from taking over your garden is to keep an eye on it and remove the weed as soon as you see it. If the weed has already taken root, however, there are several methods you can use to get rid of it:

Manual removal

The simplest way to remove onion grass is by hand. It is the most labor-intensive method but also the most effective. Simply pull up the weed by its roots and dispose of them properly.

The most effective and least expensive way to get rid of onion grass is to dig it up. Onion grass has a shallow root system and a small bulb, so it should be fairly easy to dig up. If you have a very large area, you may need some tools or hired hands to help you.

The best time of year to do this is in the spring before the weed starts growing. This will ensure that the bulb is removed rather than breaking off on top of the soil.

Onion grass is an invasive perennial weed, so after digging it up, you will need to keep an eye out for any new growth during the following growing seasons. If you do spot any new onion grass, remove it immediately.

Be sure to wear gloves when doing this, as the sap from the plant can irritate your skin.

Chemical herbicides

If hand-removal is not an option or if the weed has already spread, you can try using a chemical herbicide. Herbicides are widely used to kill weeds that grow on lawns. They contain some poisonous chemicals which kill the weeds.

A herbicide like glyphosate which will kill most plants including the weed’s roots or a post-emergent selective broadleaf weed killer which specifically targets dicots (broadleaf plants).

Since onion grass has a shallow root system, you can use weed killer in the areas where you have dug up the grass without fear that it will damage your other plants, as long as you are careful not to spray on them directly.

There are many brands and formulas of herbicides on the market, so be sure to read the label carefully before use. Be aware that some herbicides can be harmful to plants and pets, so take caution when using them.


Mulching is a great way to keep onion grass at bay. By placing a layer of mulch around your garden plants, you will prevent the weed from growing. Mulch also helps retain moisture in the soil, which can be beneficial for garden plants. There are many types of mulch available, so be sure to choose one that suits your needs.

Landscaping fabric

Another way to prevent onion grass from taking over your garden is by using landscaping fabric. This material is placed over the soil and prevents any weeds from growing. It is a simple solution, but it can be expensive if you have a large garden.

Landscape fabric is also not the most aesthetically pleasing solution, so keep that in mind when choosing this method.

Baking Soda

Put baking soda on onion grass plants to kill them. Sprinkle baking soda directly on the leaves, covering them completely. Water it in to the soil so that it gets into the bulbs below ground level.

This method is more effective in powder form than in granules, but both will work. Baking soda requires several applications to get rid of onion grass completely because it doesn’t kill existing weeds immediately but instead prevents germination of new weeds and, over time, eliminates existing ones. If rain washes away the baking soda before it has time to take effect, reapply it as needed.

Use of salt

Baking soda and salt are both good options for killing onion grass. Salt is inexpensive and readily available, plus you can use it to kill other weeds too! Just sprinkle some on top of the weed that you want gone, then water in well so that it gets down into the soil below ground level where bulbs live. The salt will cause an imbalance in their system which eventually leads to death within about two weeks time frame depending upon how much was applied initially or how often application occurs after the initial dose given off (i.e., if rain comes before all salt has dissolved).

Boiling water

This method works best when used against small patches of plants such as those found outside a home or garden. Boil a pot of water and pour it over the plants, making sure to saturate them with boiling water. Be careful not to get too close when pouring, or you may end up burning yourself.

This is an effective way to kill onion grass, but it can also damage your other plants if you’re not careful.


White vinegar will kill onion grass quickly and easily. Just mix one part vinegar with four parts water in a spray bottle and apply directly to the leaves of the weed. This method is safe for use around plants, but be sure to avoid spraying it on flowers as it will harm them.

Reapply as needed until all the onion grass has been killed.

Crop rotation

A good way to prevent onion grass from taking over your garden is by rotating crops every few years. This will help ensure that the weed does not become too established in one area of your garden and spread throughout other areas as well.

How to prevent onion grass from growing on your lawn

There are many tips that can help you get rid of onion grass.

Here are a few tips:

  1. Mow at the correct height for your turfgrass species. Short turfgrass allows weeds to invade more easily.
  2. Fertilize at least four times a year. Frequent light applications of fertilizer are better than one or two heavy applications.
  3. Irrigate the lawn only as needed to prevent wilting and encourage a deep root system. Watering deeply but infrequently will improve turfgrass health, better enabling it to compete against weeds.
  4. Keep grass growing vigorously by mowing at the proper height for your species of turfgrass.

Frequently Asked Questions

Will vinegar kill onion grass?

While vinegar may help to weaken the onion grass, it is not a guaranteed method for getting rid of it. The best way to remove onion grass is by using an herbicide.

Why do I have so much onion grass?

Onion grass will grow in areas that receive full sun, especially during the spring and fall. If you have an overgrown lawn or garden beds with excess mulch, then this could also be a reason for onion grass growth.

How do I get rid of onion grass permanently?

The best way to get rid of onion grass is by using an herbicide. There are many types of herbicides that can be used, so make sure to read the instructions carefully before use. Be sure to also follow all safety precautions when using an herbicide.

Is it safe to use weed killer near my flowers?

When selecting a weed killer, be sure to choose one that is specifically designed for use around flowers. Also, be sure to read the instructions carefully before using a weed killer near your flowers and always follow safety precautions.


Onion grass can be a very difficult weed to get rid of. It grows under the shade of other plants and can go completely undetected until it starts to make itself known by growing between cracks in your patio, lawn, or sidewalk.

In order to get rid of onion grass, it is important not to let it go too long before trying to get rid of it. The longer you wait, the harder it will be to eliminate onion grass entirely from your garden area.