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. 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 (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 Control 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.

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