Crabgrass: The Ultimate Guide to This Grassy Weed

Crabgrass is a common annual weed found in lawns and gardens worldwide. It can be difficult to eliminate, but with proper lawn care, it can be managed. Learn more about crabgrass and how to get rid of crabgrass here.

What is Crabgrass? 

Crabgrass is a summer annual grass weed widely known for its ability to quickly spread and take over a lawn when the soil warms in spring. This can lead to a significant reduction in the appearance and overall health of the lawn. It can also cause damage to your lawn by crowding out desirable grass and preventing it from receiving the nutrients it needs to grow. 

What Does Crabgrass Look Like?

Crabgrass can grow up to 15 inches high and is identified by its thin, ground-hugging mats that are typically green but turns brown or yellow when the plant dies. It typically grows in areas of thin or bare soil that receive lots of sunlight such as in the lawn or garden.

Crabgrass gets its name ‘crab’ from the way the plant grows in a similar way that a crab crawls - with its legs spreading out to the sides. The plants produce many seeds in mid to late summer that are easily spread around a lawn by wind and animals and can remain viable to re-infest a lawn for several years. 

Types of Crabgrass

Smooth crabgrass (Digitaria ischaemum)

The most prevalent variety of crabgrass found in lawns. It has smooth, wiry stems and a low, spreading growth habit.

Large crabgrass (Digitaria sanguinalis)

Although this species resembles smooth crabgrass, it differs by having larger, coarser leaves and stems as well as a more aggressive growth pattern.

Southern crabgrass (Digitaria ciliaris)

This species, which is native to the southeastern United States, is distinguished by its prostrate growth habit—lying flat on the ground—and hairy stems and leaves.

Hairy crabgrass (Digitaria hirsuta)

Hairy crabgrass is also native to the southeastern United States. It has hairy leaves and stems that give them a rough and rigid appearance. 

Crabgrass Life Cycle

Crabgrass germinates in the spring when soil temperatures begin to hit 55°F (13°C) consistently and will continue to germinate until soil temperatures reach around 80°F (27°C). Crabgrass is a warm-season annual grass that is adapted to grow during summer when the weather is warm and the soil is moist. Hard frost kills crabgrass in fall but the seeds that spread over summer still have the opportunity to germinate again next spring. 

Crabgrass on the lawn.

How to Get Rid of Crabgrass

Crabgrass can be difficult to control once it has established itself in the lawn. Here are some ways you can get rid of crabgrass. 

1. Apply Pre-emergent

Applying a pre-emergent herbicide, commonly known as a crabgrass preventer, in early spring before grass begins to germinate is the best way to control crabgrass. Pre-emergent herbicides work best when applied in early spring before soil temperatures begin to hit 55°F. It will create a barrier in the soil that prevents crabgrass seedlings from germinating.

GreenView Fairway Formula Spring Fertilizer with Crabgrass Preventer provides pre-emergent weed control of over 40 common weeds, including crabgrass and other weeds.

It also provides post-emergent crabgrass control for up to 4 weeks after it germinates, meaning if you’re late to apply the product, you will still be able to stop seedlings that have sprouted. Extended time-released nitrogen also greens your lawn into summer without excess growth.

Can be applied to many types of grass including Kentucky bluegrass, perennial ryegrass, and tall fescue (see label for full list). Read the label carefully before applying and use proper safety precautions to prevent injury.

2. Apply Post-emergent

Applying a post-emergent herbicide, commonly known as a crabgrass killer, should be your last resort in your crabgrass defense. It will kill crabgrass but will not disrupt the crabgrass seeds that have already spread around the lawn.

Choose a selective herbicide that will not kill your grass. Read the label carefully and use proper safety precautions when applying post-emergent herbicides.

3. Lawn care

Crabgrass is more likely to grow in thin, poorly maintained lawn or garden areas.

Mow at a higher setting to allow grass blades to grow longer. This will shade out crabgrass and make it harder for it to grow.

Consistent fertilizer applications will create a thick lawn that crowds out crabgrass seeds from germinating.

Also, make sure the lawn gets a healthy amount of water. This will encourage a thick lawn that will prevent crabgrass from taking over. 

4. Overseeding

If your lawn is thin or damaged, overseed with GreenView Fairway Formula Grass Seeds to increase the lawn's resistance to crabgrass growth. Overseeding is the process of planting grass seed on top of existing grass to help thicken and revitalize the lawn. This will help fill in bare spots and thin areas of your lawn, making it harder for crabgrass to establish. For best results, aerate or dethatch and mow the lawn before overseeding. 

The best time to overseed is in the Fall for cool-season grasses. However, you can still overseed in the spring if needed but it may take longer to grow because the soil temperature is cooler. 

5. Improving Soil Quality

Improving the conditions of your soil will help the grass grow thicker and fuller.

Start with a soil test in spring or fall to determine what nutrients it lacks (or has an excess of). You can get a soil test from your local extension office or you can buy one at your local gardening center.

Next, top-dress your lawn with organic matter such as compost to help improve soil fertility. Top dressing will also improve drainage, loosens compacted soil, and helps retain moisture in sand-dominant soils. Adjust pH levels by adding a product such as lime to help bring the soil to the desired acidic range. 

6. Pull Crabgrass

The crabgrass will be easier to remove if you wait for a dry day. Using a garden weeder tool, loosen and pull out the entire plant including the roots.

Place the pulled crabgrass into a trash bag and seal it tight to contain any crabgrass seeds that can still be spread.