What To Do About Crabgrass In Your Lawn

Crabgrass is ugly. It’s also strong, tough to kill, and capable of growing in adverse conditions. In this article we will tell you how to identify, prevent, and kill crabgrass in your lawn.

How do I identify crabgrass?

Crabgrass can be difficult to identify because they are easy to confuse with various types of pasture grass. Crabgrass initially shoots up like a mini cornstalk and then spreads outward with long, purple branches and thick blades that fold down the middle. 

Image University of Illinois

For more help identifying crabgrass, look at the images on this page by the Garden Counselor Lawn Care.

Crabgrass seeds begin to germinate when soil temperature reaches 55 °F for several consecutive days. In Salt Lake City, crabgrass typically isn’t visible until mid May.

How do I prevent crabgrass?

Hands down, the best way to prevent crabgrass is to build a thick and healthy lawn. A healthy lawn takes up space and resources from all weeds and prevents crabgrass seeds from receiving sufficient sunlight.

Here are ways to keep your lawn healthy and thick to fight off crabgrass:

• Water longer and less frequently to make your grass roots grow deeper.

• Don’t mow your grass too short. It should be about 2-3 inches long after mowing.

• Use slow-release fertilizer. If fertilizer is released too quickly, it causes long-term damage and feeds weeds.

• Most importantly, you should seed thin or bare grass spots every year in order to keep your lawn thick. If the area is really bad, you can sod it.

Another way to prevent crabgrass is to use pre-emergent. Pre-emergents are difficult to use because they must be timed with the weather, which is always unpredictable. The best time to put down pre-emergent is mid spring when the soil temperature is 55 °F. You may even consider putting down two rounds of pre-emergent to increase your odds of preventing crabgrass.

How do I kill crabgrass after it sprouts?

The earlier you kill the crabgrass, the better. When the weeds are young, pull them out manually. If there are too many too pull, use a selective herbicide specifically for crabgrass. Unfortunately, crabgrass herbicides are slow and mildly effective. For this reason, the only way to really beat crabgrass is to prevent it from growing in the first place.

Once the fall has arrived, it’s not worth spraying crabgrass. The spray becomes less effective and the crabgrass will begin dying soon anyway.