Complete Crabgrass Guide

When people see weeds in their lawn that aren’t dandelions or clovers, crabgrass is often the first weed that comes to mind when they try to guess at what the weeds might be. But is it actually what they’re looking at, and how can they tell if it is crabgrass?

If you’re curious about crabgrass, then you may find this guide helpful as it will give you a good understanding about crabgrass as it will explain:

• What crabgrass is,
• What crabgrass looks like,
• What crabgrass will do your lawn,
• Where crabgrass came from, and
• How to get rid of crabgrass!

What is Crabgrass?

Hairy or long crabgrass (Digitaria sanguinalis), smooth crabgrass (Digitaria ischaemum), and southern crabgrass (Digitaria ciliaris) are all non-native grasses to the U.S. – meaning they are considered invasive weeds in your lawn. Which should come as no surprise! 

Crabgrass has low-spreading, flat blades that grow out horizontally from the base (a process called tillerin) forming a clump. Its leaves are lime-green and coarse in texture. The seedheads appear in finger-like spikes called racemes.

To help in identifying crabgrass, use the chart comparing and contrasting its characteristics with other types of commonly occurring weeds and grasses. You can also visit our Georgia Weeds Resource to learn about other weeds that are common in the area. 

Where Did Crabgrass Come From?

Originally, the plant was imported into Europe from Africa. Africans still use crabgrass seed known as Fonio for food. Likewise Europeons milled the seed to add to breads, porridge and other food and to make beer. They also planted it as animal forage.

As European immigrants entered the U.S. in the 1800s, they carried crabgrass seeds with them. In 1869, the U.S. government imported it officially to use for draft horse forage. Over time it was no longer used as a food additive but was still cultivated as animal forage up to the 1940s. Thereafter crabgrass spread like wildfire and took up residence in any field that was plowed thus becoming the bane of both commercial farmers and homeowners.

What Will Crabgrass Do to Your Lawn?

Crabgrass should be extremely concerning for homeowners because it spreads rapidly, kills grass overtime, and is difficult to control. Until some recent herbicide products were introduced, crabgrass has been very difficult for homeowners to eradicate from a lawn once it has spread. 

Nature designed crabgrass to propagate from a single plant that produces 150,000 seeds each year. It can quickly overtake and smother lawns and even plants in a vegetable garden. Crabgrass can also withstand extreme weather conditions, so it thrives in both cold climate zones and tropical zones.

While the plant itself dies with the first frost, seeds can lie dormant for several years below the soil. Germination requires a lot of sunlight and the plant needs about six hours of sun a day to thrive. A lack of sunlight will keep the seeds dormant indefinitely.

This is why it’s critical to work with a professional weed control team that can apply the right pre-emergent herbicide to your lawn before the crabgrass seeds germinate in the spring. 

How to Remove Crabgrass from Your Lawn

Knowing the damage crabgrass can inflict on your lawn, you may be wondering what in the world you can do to prevent it from taking over. Here’s how you can remove crabgrass from your yard and how you can prevent it from growing back. 

Maintain a Thick Lawn

If you don’t have crabgrass in your lawn yet, but want to take preventive measures, the best way to keep it away is to maintain thick turf that blocks sunlight from reaching any dormant crabgrass seeds. Apply nitrogen fertilizer in early fall and again in the spring as needed along with turf seeding. Mow your lawn regularly and at the highest height recommended for your grass in order to fill in any voids and create a lush canopy of grass.

Where severe crabgrass or goosegrass infestations are present in summer, a late summer or early autumn overseeding of cool-season grass is a valuable management practice. Seeding at this time will fill the voids created as these weeds die, preventing crabgrass and goosegrass seedling survival the following spring.

If you do find crabgrass in your lawn, below are steps you can take to remove it and keep it from re-growing.

Dig It Out

If you only have a few plants, digging it out by hand in the early spring is recommended, but you will likely need to do this process more than once to achieve lasting results.

Follow these steps:

1. Pull out plant from base of stem to get both roots and side shoots.
2. Place in a trash bin immediately to prevent spread of seeds.
3. Hoe or till soil so plant nodes and seeds are buried too deep to germinate.
4. Treat soil with weed preventatives containing trifluralin like Oxadiazon and Benefin which will prevent re-germination for 2 months and is safe in gardens.
5. Put a layer of mulch over the area to prevent sunlight from re-germinating any seeds.

Apply Herbicides

There are several crabgrass killer herbicides available on the market. Look for the active ingredient sethoxydim as it kills crabgrass without hurting other grasses.

Be aware that using the same herbicide over and over can create grasses that are resistant to eradication. So vary the type of herbicide and use a pre- and post-emergent application. Some pre-emergence application herbicides should be applied more than once in the early spring.

As soon as forsythia blooms in your area, apply an herbicide as soon as possible. Don’t apply until the lawn has been unmowed for about a week allowing the crabgrass’ broad leaves to soak up the chemical. Also choose a day with no rain and no rain forecasted for a couple days and where temperatures are not expected to go above 85 degrees Fahrenheit. Apply in a cooler time of the day like the early evening and don’t water your lawn for at least 24 hours.

If you are unsure how to use herbicides, consider calling in a lawn care expert who can assess the issue and apply the right herbicide on a regular basis to prevent the return of crabgrass.

About Simply Green’s Weed Control Service

Simply Green offers a variety of weed control and fertilization programs to meet your specific needs. We will carefully evaluate your lawn to determine the best course of action.

Our weed control services are designed to target specific types of weeds and address the underlying issues that are causing them. Each service is customized based on the type of grass you have, the time of year, and your lawn’s specific needs. We only use high-quality products that are safe for your family and the environment.