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How to Kill Crab Grass During the Summer

lawn,grass image by Greg Pickens from

Crabgrass is never a welcome addition to anyone's lawn. Bruce Spangenberg, a horticulture educator at the University of Illinois, warns that, as the summer weather gets warmer, you should be on the lookout for the emergence of crabgrass. Dry heat is another welcome mat for crabgrass. As your lawn begins to wilt in the dog days of summer, crabgrass begins to take hold. Your best course of action is to keep your lawn as healthy as possible, so it can be its own defense against a crabgrass invasion.

Set your lawn mower higher. Cutting your lawn to a height of 2 to 2 ½ inches helps to inhibit the growth of crabgrass.

Water your lawn deeply. Create a watering schedule for your lawn in which you water less frequently, but saturate the soil to a depth of 4 to 6 inches. This practice strengthens the root system of your lawn, making it more difficult for crabgrass to penetrate.

Fertilize your lawn. A healthy, lush lawn is the best defense against a crabgrass invasion. The thicker your lawn, the more competition it provides against crabgrass.

Use a post-emergent herbicide to treat crabgrass directly. Spot treat your lawn for visible crabgrass that has taken hold. The sooner the crabgrass is killed, the less likely it will have the opportunity to germinate and spread .

Kill Crab Grass Organically

There are roughly 33 species of crabgrass, notably, hairy crabgrass (Digitaria sanguinalis spp.) Doing so allows the healthy lawn grass to develop a deeper root structure. Crabgrass is often caused by low mowing conditions and bare spots in the lawn. While you’re at it, change the pH of the soil, making it more acidic or more alkaline. * Add salt or vinegar for additional strength. This will disturb the condition of the soil, so be cautious when applying; the surrounding plants will be exposed as well. Stubborn weeds may require several applications. * Yummy sugar creates harmful soil, halting plant growth. Experiment with one or any combination of these options. Alternately, you can use another household staple to kill crabgrass: salt or baking soda. Because they make the soil hostile to plants by changing the pH balance, these substances should be used to kill crabgrass only where you want nothing else to grow in that area.


Applying a pre-emergent herbicide in the spring, before crabgrass has a chance to grow, is more effective than treating existing crabgrass.


It may take two applications of a post-emergent herbicide to kill off crabgrass entirely.

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