This weed can become quite a problem if not managed, quickly taking over lawns and garden beds.

By Kelly Roberson
Updated July 13, 2020
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Have you nursed your lawn or flowers all summer, only to find them riddled with brown patches after autumn's first frost? In all likelihood, those unsightly spots aren't dead areas, they're crabgrass. This annual grass is a universal problem to homeowners in the U.S. It pops up in spring and develops into large, flat, thick clumps that spread widely, crowding out surrounding lawn grass and other plants. Because it's an annual, crabgrass dies after the first frost in autumn, which leaves behind patchy, bare spots in your lawn. If left untreated, those bare spots will fill in with more crabgrass or other weeds next spring when their seeds sprout. Before it starts damaging your grass, here's how to get rid of crabgrass  with organic methods and by pretreating your lawn in spring.

Crabgrass Clover Section
Credit: J Wilde

Crabgrass Control Methods

Crabgrass loves hot, dry weather, so you'll usually see it begin popping up in spring, then flourishing over the summer if it's not dealt with right away. One of the best ways to control crabgrass is to maintain a lush, thick lawn and well-mulched flower and vegetable beds. Healthy landscapes (lawns that are dethatched regularly and mowed to an appropriate height, or garden beds that are given enough water and nutrients) are less likely to be stressed and better able to shade out any weed invaders like crabgrass. Plus, it's easier to pull up crabgrass from soil that is damp, rather than dry.

Rely on an organic mulch to help control crabgrass naturally (without chemicals) in garden beds. Mulch acts as a suffocating blanket by preventing light from reaching weed seeds. At the same time, mulch holds moisture for your plants and provides nutrients for your soil as it decomposes. Apply coarse mulch, such as bark or wood chips, directly onto soil. Shredded leaves, grass clippings, or straw work better as weed deterrents with a separating layer of newspaper or cardboard between them and the soil.

To prevent crabgrass from sprouting on your lawn, apply a preemergent weed killer with corn gluten meal in the spring, two weeks before your last expected frost. This will kill the crabgrass seed before it has a chance to take root. However, don't use any preemergent products when you're planting other seeds; they will prevent all seeds from germinating, not just the weeds.

The best indicator for applying crabgrass preventer during the season? Forsythia. This popular landscape shrub is grown for its striking yellow flowers in early spring, when most trees and shrubs are still bare. When the blossoms start to drop to the ground, it's time to put down the crabgrass preventer.

removing crabgrass
Credit: Jacob Fox

How to Remove Crabgrass

Crabgrass also can be eliminated with a product labeled as a crabgrass killer or a non-selective weed killer. If you prefer to avoid products with synthetic chemicals, look for ones that contain vinegar or you can make your own vinegar weed spray. Always make sure to follow label instructions when using weed killers. Even vinegar-based ones can burn skin, eyes, and lungs so carefully apply it only to the plants you want to kill.

If you find crabgrass in your edible garden, weeding it out by hand is best. This plant has shallow roots, but using a weed pullers or a trowel as a crabgrass removal tool will make the job easier. Don't toss the uprooted weeds in your compost pile, though, because they could still reseed themselves. It's better to toss in the trash.

If you pull up crabgrass from your lawn, prevent it from coming back by filling in the bare patch with grass seed. Cover it with a light layer of topsoil, and water well to help the seeds sprout. Wait to mow the new grass until it reaches at least 3 inches tall.


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