Controlling Crabgrass in Your Lawn

Controlling Crabgrass in Your Lawn

Sod University

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.

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.

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 (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. Another option is Tupersan (active ingredient siduron), which will not damage newly seeded lawns and can be applied with a starter fertilizer. For both of these chemical options, 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.  

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.

Want to learn more about achieving a great lawn? Check out our other Sod University tips here.

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