Crabgrass: A Complete Guide

Crabgrass is one of the most common invasive lawn weeds across the United States. As its name suggests, it grows outward (called a prostrate growth habit) with multiple stems that look like legs. It is generally a light green color, which can help differentiate from your healthy lawn grass. There are two prominent species: hairy and smooth. The main difference between the two is that hairy crabgrass grows longer and, per its name, has leaves covered in fuzz, whereas smooth crabgrass does not grow as large. Smooth crabgrass can also occasionally have stems that are red in color. It tends to thrive in hotter climates, first appearing in spring, with seeds germinating when soil is between 55- and 65-degrees Fahrenheit. If you have a particularly aggressive crabgrass infestation, reach out to a local lawn care expert to ensure you are solving the problem in the best way possible.

How To Kill It

Luckily, you have multiple options when it comes to eradicating crabgrass from your lawn. A post-emergent herbicide, meaning one meant for already existing weeds, is one of the most popular and effective ways of killing crabgrass. There are multiple kinds of post-emergent herbicides ranging in strength for dealing with different severities of crabgrass infestations. It is also important to select your herbicide based on the turf grass your lawn consists of. For example, fenoxaprop-p-ethyl is a powerful herbicide that can be used on crabgrass on any stage in its development, however, if you have Kentucky bluegrass it might cause some damage to your yard if temperatures get too high. This kind of herbicide is called a selective herbicide, because it targets only certain species of plants without killing the desired ones.

Mesotrione is another commonly used post-emergent selective herbicide and is most effectively used for new crabgrass infestations in cool-season turf grasses, like Kentucky bluegrass and ryegrass, but will also work on centipede and buffalograss lawns. Do not use mesotrione on a St. Augustine grass, zoysia grass, or bermudagrass lawn as it will damage it.

Quinclorac is a great post-emergent selective herbicide effective against a variety of different weeds, including crabgrass, clover, and dandelion, while not damaging most types of turf grasses, except for some warm-season varieties such as bahiagrass and centipede grass.

If you have a warm-season grass lawn, especially St. Augustine grass, your choices for post-emergent selective herbicide are much smaller. Some exist; however, they are generally products containing natural ingredients such as vinegar or baking soda, which might or might not have the desired effect on your crabgrass infestation. To eradicate the problem, you will most likely have to use a non-selective herbicide like glyphosate, which will kill every plant it comes in contact with. For this reason, it might be helpful to elicit the help a professional to ensure you do not damage your lawn. A lawn care expert will also be able to help you develop a plan to avoid crabgrass infestations in the future by using pre-emergent herbicide

How To Prevent Crabgrass

To prevent crabgrass, you can use an herbicide called a pre-emergent. These kinds of herbicides are meant to be used before the weed seeds have germinated, so they are a preventative measure. The best way to apply pre-emergent depends on where you, as crabgrass seeds stay dormant in the winter but begin to sprout once soil temperature gets above 60 degrees Fahrenheit. Generally, early spring and fall are the best times to apply pre-emergent for the most effective treatment.

How To Remove Crabgrass By Hand

If your crabgrass infestation is not particularly severe, it is perfectly acceptable to remove it by hand. Whether you simply pull them or use a tool such as a hoe, spade, or dedicated weed puller, it is imperative that you remove the root entirely to ensure the crabgrass is not given the chance to grow again and spread more seeds

How Mowing Prevents Crabgrass

Regular lawn maintenance, including mowing and watering, can actually be a great preventative method for crabgrass. Different lawn grass types have different optimal heights for each season and ensuring that you mow to these heights will provide shade that will prevent crabgrass seeds from getting the sunlight they need to germinate, grow, and spread. Mowing at optimal height will also prevent scalping of your lawn. When done intentionally, scalping is a great way to stimulate your lawn coming out of hibernation to begin growing again. However, if you repeatedly mow your lawn at the lowest setting, you run the risk of damaging and killing your grass. This can lead to bald patches that are the perfect spot for crabgrass to take root and begin its infestation.


For help with determining the best lawn care plan to keep your lawn free of crabgrass, reach out to us here at LawnCare.Net. Our network of experts can recommend the services needed to keep your lawn looking its best.

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