What Kills Onion Grass?

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What kills Onion Grass? Something you may be wondering after trying several weed killers or other remedies, you may be frustrated that it’s taking so long and you want to know how to get rid of onion grass completely without damaging anything else in your garden or lawn.

What kills Onion Grass

What is Onion Grass?

Onion Grass (Allium vineale) is a very common lawn weed. It looks like grass and grows in clumps of fine, narrow leaves that are basically hollow on the inside. It has a very strong onion odor when crushed or mowed and can be a problem in grazing areas, but it is not considered poisonous.

When the weed is growing it has a round stem that is solid and very similar in size to most other weeds. It turns woody after flowering, but with its round stem and fibrous roots, it does not spread as aggressively as other weeds such as dandelions or yarrow. Onion grass does not spread by seed or rhizomes.

It’s easy to identify onion grass by its strong onion smell when crushed. The leaves grow up through the center of the plant, showing their hollow nature, and then arch around at the top of the plant forming a cluster of leaves. Onion grass blooms from late spring through early fall if it hasn’t been mowed or otherwise disturbed. The flowers are small, star-shaped heads that droop. They are white to purple in color depending on the variety.

What Kills Onion Grass

A quick solution, if you don’t have much of the weed, is simply to dig up the onion grass by pulling it out of the ground with a shovel. keep on checking for about two months to make sure that no more onion grass comes back.

Onion grass is a perennial weed that can be very difficult to get rid of, so prevention can be the best strategy. After you pull up onion grass roots, the best way to protect your lawn from it coming back is to apply a preemergent herbicide. Pre-emergent herbicides are applied to the soil before the weeds start growing and they prevent seeds from ever germinating. This will keep your lawn clear of more onion grass for a longer
period of time.

Here are two-step instructions on how to apply pre-emergent herbicide:

1. Mow your lawn as low as possible (1/2″ or less). It’s better to do this in late summer/early fall rather than spring since you’re more likely to have trouble finding the correct instructions and applying it in colder weather.

2. Use a drop spreader with 1-2 pounds per 1000 square feet of herbicide. Follow all instructions carefully when applying and make sure you water it in within 48 hours or it won’t work.

Final tip: know your Onion Grass!

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