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Oregon State University

OSU Extension Service

Q:

I’m having a problem with crabgrass on my lawn. How do I get rid of it?

A:

It's vital to monitor your lawn regularly for new crabgrass growth and act promptly. Correct identification and timely management can significantly reduce crabgrass populations over time.

The best defense against crabgrass is to maintain a healthy and dense turf. Ensure that your lawn is mowed to the proper height, usually around 3-4 inches, to promote thick grass and shade the soil, which helps prevent crabgrass from germinating. Regularly feeding your lawn and adequate watering also supports healthy grass growth, making it more competitive against weeds like crabgrass

Environmentally friendly solutions:

  • If the infestation is small, hand pulling can be effective. This should be done when the soil is moist to make it easier to remove the roots. Make sure to dispose of the pulled plants properly to prevent reseeding.
  • Pour boiling water on patch, but beware, this will also kill good grass.
  • Spray with vinegar — not cooking strength, it should be 20% — and you might need to spray several times.
  • Mulching: For garden areas, applying a 2- to 3-inch layer of mulch can suppress germinating weed seeds, including crabgrass, by blocking sunlight.

Chemical solutions — you must follow the instructions on the label:

  • Applying a preemergent herbicide before the crabgrass seeds germinate is one of the most effective chemical controls. It's best to apply this in early spring when soil temperatures consistently reach about 55°F for several days. Or use a post-emergent herbicide, which isn’t necessarily safe for children or pets.
  • If crabgrass is already established, a post-emergent herbicide can help control it. Apply these products to young crabgrass plants before they mature. It's essential to follow label instructions carefully since some herbicides can damage desired grass species.

To prevent crabgrass and other weeds:

  • Mow your lawn at the proper height for your grass type.
  • Feed regularly — 6-2-4, for example — or put down thin layer of compost.

Deep water your lawn. Shallow, frequent watering encourages shallow root growth which allows for weed growth.

Related content

How to grow and maintain a healthy lawn

Maintaining a healthy lawn requires a little knowledge and a big commitment to regular maintenance. Learn what it takes, from seeding or sodding to fertilizing, watering, mowing and aerating.

Weston Miller |Mar 2022 |OSU Extension CatalogPeer reviewed (Gray level)

Practical Lawn Establishment and Renovation

This publication will take you through the steps needed to successfully plant a new lawn or renovate an old one. If you follow these steps, you will get it right the first time!

Tom Cook |Sep 2022 |OSU Extension CatalogPeer reviewed (Orange level)

Use pesticides safely!

  • Wear protective clothing and safety devices as recommended on the label. Bathe or shower after each use.
  • Read the pesticide label—even if you’ve used the pesticide before. Follow closely the instructions on the label (and any other directions you have).
  • Be cautious when you apply pesticides. Know your legal responsibility as a pesticide applicator. You may be liable for injury or damage resulting from pesticide use.
thick grass
Want to learn more about this topic? Explore more resources from OSU Extension:Lawn and turfgrass,Weeds
crab grass in lawn
Credit: Christian Delbert - stock.adobe.com
Mar 2025
Author
Deb Kern
Benton County Master Gardener
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