Why Is Crabgrass Bad for the Lawn?

If it’s a type of grass, why is crabgrass bad for the lawn? For starters, it’s not a ‘turf-type’ grass like your lawn. Crabgrass is a nasty weed that can take over your turf and jeopardize the lawn’s health.

This invasive annual weed can easily spread over your entire lawn if you let it, eventually invading your garden beds. Too much crabgrass will lead to pest problems, bare patches, and stolen resources intended for your grass (such as fertilizer and water). 

When you’re ready to remove this weed from your landscape, we’ll show you how to control and prevent crabgrass, too.

What Is Crabgrass?

Crabgrass, also called Digitaria sanguinalis, is a warm-season annual grassy weed that germinates in the early spring to late summer. It gets its common name from the stolons it uses to spread, which resemble the legs of a crab. Crabgrass is a very opportunistic plant that will grow wherever it can, including suburban lawns.

Crabgrass is originally native to Europe, but was introduced to the United States somewhere around the mid-1800s. It grows in just about every state in the U.S. and can adapt to a variety of different environments, including areas with very poor soil.

How Does Crabgrass Hurt Your Lawn?

Crabgrass is an invasive weed, which means that it harms the other plants in its environment by crowding them out and taking valuable nutrients and water. Left alone, crabgrass can take over your lawn and choke out your garden plants. And that’s not even the worst of what crabgrass has to offer.

Steals Resources From Turf

Crabgrass grows much faster than your turfgrass, soaking up valuable nutrients, sunlight, and water like a sponge. As your turfgrass loses resources to crabgrass and other weeds, the health of your lawn will greatly suffer.

Chokes Out Grass

Crabgrass will also choke out your grass if it’s allowed to stay for too long. This means that the crabgrass will prevent your grass from growing by blocking water and nutrients from getting to the lawn’s roots. As a result, the grass gets weaker. The crabgrass will then start to crowd out the weakened grass and overtake it, replacing your lawn with more crabgrass.

Attracts Pests and Disease

In addition to pushing out your lawn and the other plants in your landscape, weeds like crabgrass attract undesirable pests and disease. How? As the lawn grows weaker, it becomes susceptible to damage from pests and fungi. Crabgrass also provides pests with food and hiding spots that they won’t find in healthy, well-maintained turfgrass.

Releases Natural Herbicide

All weeds are bad for your landscape, but crabgrass in particular will harm your lawn by producing chemical compounds. These compounds act as a natural herbicide that harms or kills any nearby plants, including grass. This technique is known as allelopathy. These chemicals can also harm the beneficial soil microbes that are very important for the health of your lawn.

Depletes Nitrogen

Another problem with crabgrass is that it depletes your soil’s nitrogen. While crabgrass will steal all the nutrients it can get its hands on, it’s especially a problem for nitrogen due to its allelopathy (mentioned above). The allelopathy damages the soil microbes, which are essential for converting nitrogen into a form plants can use.

In addition, crabgrass can survive and even thrive in a nitrogen-poor environment, so while your grass is getting weaker due to the lack of nitrogen, the crabgrass is only getting stronger.

Creates Bare Patches

Crabgrass is an annual plant, which means that it dies off during the winter. When that happens, it leaves bare patches behind until the crabgrass seeds germinate and grow back. That bare spot is vulnerable to erosion, becomes compacted, loses nutrients and water and it can either crack or quickly become mud.

Bare soil is also weaker overall than healthy, covered soil and can even die if left bare too long. Your soil is an entire ecosystem full of living things. Leaving it bare makes it vulnerable, so keeping crabgrass away is vital for the continued health of both your grass and soil.

How to Get Rid of Crabgrass

The two main methods for removing crabgrass are hand weeding and a post-emergent herbicide. Hand weeding is less destructive to your lawn, but isn’t as effective. You’ll likely need an herbicide to eradicate crabgrass completely, and even that will be a long and difficult process. For more information about controlling crabgrass, read our article on How to Get Rid of Crabgrass In Your Lawn.

FAQ About Crabgrass

How much does professional weed control cost?

If you’d rather not deal with weeds yourself, you can hire a professional to do it for you. On average, homeowners can expect to pay a total of $65 to $165 for professional weed control on a one-quarter acre lot.

Thankfully, annual weeds like crabgrass are easier to control than perennials, so your final cost shouldn’t be too pricey so long as other factors don’t drive it up.

Does mowing crabgrass make it spread?

Yes. Crabgrass spreads through both seeds and stolons, which are stems that grow horizontally and form new plants. These stolons have seeds of their own inside of them, and if you mow them, you’ll send those seeds flying across your lawn. Never mow crabgrass if it’s already gone to seed. To be safe, don’t mow it at all. Instead, pull it up by the roots.

Why is crabgrass so hard to get rid of?

There are multiple factors that make crabgrass such a stubborn weed. It’s primarily a combination of it spreading so many seeds and the plant being hardy enough to survive high temperatures, mowing, and foot traffic.

Is crabgrass good for anything?

Sort of. Believe it or not, crabgrass is partially edible. The seeds are commonly used as a grain in other parts of the world. They can be ground into flour, and the grass itself can be used as animal feed.

Find Your Lawn Expert

Without intervention, crabgrass can take over your lawn. Give it the boot whenever you find it to protect your grass and garden plants.

If you need help preventing and controlling crabgrass, contact lawn care professionals near you. They can treat the lawn to ensure it remains thick and healthy, and keep it crabgrass-free.

Main Photo Credit: Christian Delbert / Adobe Stock

Austin Geiger

Austin Geiger is a lover of all things nature. He enjoys writing comprehensive, easy-to-swallow articles about pest management solutions, landscaping tips, and ways for people to help their local pollinators.

Posts by Austin Geiger