Controlling Crabgrass in Your Lawn

Controlling Crabgrass in Your Lawn

Controlling Crabgrass in Your Lawn

Crabgrass is a pervasive weed found throughout the continental United States that many lawn owners struggle to control. Appropriately named, crabgrass grows close to the ground and has branching stems resembling crab legs. Due to this growth habit, crabgrass is very adaptable to short mowing heights and can continue to produce seed even when mowed as low as ½ an inch. Crabgrass is also quite drought tolerant and thrives in the hot conditions that the summer brings.

As an annual weed, crabgrass remains present in the landscape for one growing season, which usually begins in the late spring and early summer after the soil temperature has reached a temperature of 55 to 60 degrees for over five days. Once the plants germinate, they will continue to grow until the days begin to shorten, causing them to enter a reproductive stage. During this time, plants produce seed (up to 150,000 per plant!) until the first frosts of the fall hit and knock them out. Even if crabgrass isn’t visible in your lawn during the fall and winter, if the plant was able to set seed, prepare begin fighting it again come warmer weather.

Non-Chemical Crabgrass Control Methods

There are many control options available to help ensure that this season is that last time crabgrass invades your lawn. Some natural prevention methods to strengthen your lawn include:

    1. Raising the mowing height: This will help keep the soil cool by keeping the sunlight out, making it more difficult for the crabgrass to germinate and take over
    2. Watering deeply once a week: Avoid light irrigation that would allow weed seed to germinate, and make sure your lawn is well watered and healthy before germination begins
    3. Avoid fertilizing in the summer: Make sure fertilizer is applied before the crabgrass begins, this will keep your lawn thick and give it the upper hand

Crabgrass found in Gainesville, Florida.

How to Kill Crabgrass with Herbicides

If these methods do not prevent crabgrass entirely, chemical controls can be implemented. Pre-emergent herbicides will be your first chemical line of defense, as they can stop the weed seeds from germinating. One option is Dimension 2EW (active ingredient dithiopyr), which has a long-lasting window and can kill seeds that germinate at various times. This product has also been effective as an early post-emergent herbicide against crabgrass. Timing of application is everything. The success of the application will depend on getting it out before the seeds germinate, so pay close attention to the changing temperature! For post-emergent control, Tenacity (active ingredient mesotrione) is a newer product that looks promising at minimizing crabgrass competition so that your lawn can flourish. Quinclorac is a tried and true method of control that when applied correctly, is extremely effective. Lastly, Spectracide Weed Stop For Lawns + Crabgrass Killer is a great weed control product that controls over 250 various types of weeds and easily hooks up to the end of your garden hose.

  • Coverage: 0.28–0.73 oz. per 1,000 sq. ft.
  • Active Ingredient(s): Dithiopyr 24%.
  • Ease of Use: Requires tank mixing and application with sprayer.
  • Best Used On/For: Established turfgrass before weeds appear.

  • Coverage: Covers one to two acres when mixed properly.
  • Active Ingredient(s): Mesotrione 40%
  • Ease of Use: Requires tank mixing and application with sprayer.
  • Best Used On/For: Difficult to remove outdoor weeds such as crabgrass.

  • Coverage: Apply 0.367 oz. of Quinclorac per 1,000 sq. ft.
  • Active Ingredient(s): Quinclorac 75%
  • Ease of Use: Requires tank mixing and application with sprayer.
  • Best Used On/For: broadcast and spot treatment application on certain warm and cool season grasses.

  • Coverage: Covers 5,000 sq. ft.
  • Active Ingredient(s): 2,4-D, Dimethylamine salt 3.74%, Quinclorac 1.79%, Dicamba, dimethylamine salt 0.43%, Sulfentrazone 0.22%.
  • Ease of Use: Hooks up to the end of your garden hose for even spray application.
  • Best Used On/For: General outdoor weed control and crabgrass.

As always, read the label carefully before applying to ensure that the chemical will not hurt your lawn!

To learn more about identifying what kind of weeds you may have in your lawn so that you know how to best remove them, check out our Identifying Common Lawn Weeds blog. For more information on weed control in general and the best ways to reduce weeds, visit our Weed Control blog.

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