Why Your Lawn Is Full of Crabgrass and How to Stop It From Taking Over the Whole Yard

Crabgrass (Digitaria spp.) is one of the most common lawn weeds, but it can be difficult to catch before it gets too big. This grass-like weed sneaks into lawns unnoticed and can eventually take over. It’s hard to get rid of once it takes hold, so catching it early and understanding why it’s in your yard in the first place is vital.

Crabgrass emerges in the spring when temperatures reach around 60°F. This common lawn weed then germinates and begins growing in your yard. It can ruin the look of a perfectly lush lawn and it can also signal other issues at play.

Here’s what crabgrass is trying to tell you about the health of your lawn. Plus, I’ll share tips to prevent crabgrass taking over your entire yard.

What Is Crabgrass?

Crabgrass is an annual grass-like weed that is common in lawns. It looks similar to turfgrass, but it is often lighter in color and grows in clumps that turn into patches across lawns. It thrives in full sun and is often found in areas with thin turfgrass or bare spots in the garden.

Crabgrass dies off as the summer ends, but can set large amounts of seeds from the tassel-like flowers it forms throughout the growing season. These become the next year’s weed infestation, so it’s important to deal with crabgrass before it sets seed.

Why Your Yard Is Covered in Crabgrass

Crabgrass, like many other common weeds, can signal other underlying problems in your lawn. Healthy lawns are less likely to be impacted by crabgrass. So weeds, as annoying as they are, can actually tell you important information about your lawn care routine and how to improve it.

1. Compacted Soil

Crabgrass is a common symptom of compacted soil. Too much foot traffic, heavy machinery from construction, a lack of aeration, and heavy clay soil can all contribute to this problem.

Aerating your lawn is an easy way to prevent and fix compacted soil in your yard. You can either hire a professional to do this necessary job for you or you can try it yourself. There are battery-powered aerators, like this one from Ryobi, that you can rent or buy. But if you have a small yard, you can just use a small manual aerator, like this bestselling aerator from Amazon.

2. Thinning Grass & Bare Patches

Thinning grass and bare patches of soil in your lawn are also prime breeding grounds for crabgrass. Thinning is often caused by too much shade, lack of overseeding, common lawn diseases and pests, and removing a large amount of weeds from your lawn.

Overseeding your lawn is a good way to fill in bare patches or areas of thinning turf. The type of lawn seed you need depends on your growing zone and the light conditions in your yard. But Home Depot has a wide selection of grass seed for every part of the country.

3. Mowing Too Much

Mowing your lawn too short or too frequently can also encourage crabgrass. If grass blades aren’t long enough to capture the required sunlight to grow a strong root system, this can encourage bully weeds like crabgrass to take over.

Follow the one-third rule when it comes to mowing your lawn. Only cut off one-third of the length of the blades to ensure your grass has enough surface area to get the required sunlight and to also shade out small weeds.

How short you mow your lawn should also change with the seasons. As heat rises and growth slows down towards the end of summer, it’s time to cut back on mowing.

4. Improper Fertilizing

Not fertilizing your lawn enough can cause turfgrass to weaken and crabgrass to take hold. However, overfertilizing is also detrimental to the health of your lawn and can encourage crabgrass and other weeds. Fertilizing during the heat of summer or too frequently can stress turfgrass and cause it to weaken, which gives weeds an advantage.

Use a fertilizer combined with a pre-emergent herbicide, like this one from Scotts, that not only feeds your lawn but prevents crabgrass as well. Feeding your lawn at the beginning of the season with a fertilizer like this sets up your lawn for healthy growth all summer.