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how to get rid of crabgrass

How to Get Rid of Crabgrass

Weeds can be unsightly in an otherwise perfect, healthy lawn. Not only are they sometimes ugly, but they also compete with your lawn for space, sunlight, water and other nutrients! One of the most notorious weeds known for its difficulty to control is crabgrass. If you’re one of the unlucky homeowners who have it in their lawn—not to worry! Read on to learn more about how to get rid of it.

What is crabgrass?

Along with goosegrass, it is a pervasive weed found throughout the continental United States that many lawn owners struggle to control.

As an annual weed, it remains present in the landscape for one growing season, which usually begins in the late spring and early summer after the soil temperature has reached a temperature of 55 to 60 degrees for over five days. 

Once the plants germinate, they will continue to grow until the days begin to shorten, causing them to enter a reproductive stage. During this time, plants produce seed (up to 150,000 per plant!) until the first frosts of the fall hit and knock them out. 

Even if it isn’t visible in your lawn during the fall and winter, if the plant was able to set seed, prepare to begin fighting it again in warmer weather.

What does crabgrass look like?

Appropriately named, it grows close to the ground and has branching stems resembling crab legs. Large crabgrass tends to have a dense coating of hair while smooth crabgrass does not. In smooth crabgrass, you can occasionally spot a pinkish red center where the grass is growing from.

A seed head grows from different parts of the stems and has soft little spikes growing from them.

Crabgrass images

Crabgrass found in Gainesville, Florida.

How to get rid of crabgrass

If you’ve identified it early on and only a few weeds are present, it can be pulled by hand and may not grow back again. However, if it turns into a recurring problem or is too extensive to pull by hand, many chemical options serve as killers. Some methods for controlling it are by using a pre-emergent or post-emergent herbicide.

How to Kill Crabgrass

Chemical control is often the best approach if it has spread throughout your lawn. As previously mentioned, it produces up to 150,000 seeds per plant, so chemical control may be more effective. 

While there are many herbicide options available, they will typically fall under one of the following categories: pre-emergent herbicides and post-emergent herbicides. Both types are typically necessary for controlling it since it’s such a tricky weed.

Start by using a pre-emergent herbicide to prevent it…it’s more effective.

Pre-emergent herbicides are used to prevent weeds from appearing while post-emergents are used to treat currently existing weeds. Use pre-emergents before the first frost in your area in the fall and before soil temperatures reach 70 degrees Fahrenheit. 

One option is Dimension 2EW (active ingredient dithiopyr), which has a long-lasting window and can kill seeds that germinate at various times. This product has also been effective as an early post-emergent herbicide. The timing of the application is everything. The success of the application will depend on getting it out before the seeds germinate, so pay close attention to the changing temperature! 
Pre-emergents are often the most effective method for controlling it. Once it appears in your lawn, it becomes harder to control. Learn more about spring pre-emergents here.

Use a post-emergent herbicide when weeds are currently present.

If it has already established itself, the question then becomes “what kills it?”. A post-emergent herbicide will be necessary at this point in the game. Even if you applied a pre-emergent on time, it’s good to apply a post-emergent to kill any current weeds before they begin spreading.

For post-emergent control, Meso 4SC Select (active ingredient mesotrione) is a newer product that looks promising at minimizing competition so that your lawn can flourish. However, this product should not be applied on zoysia grass as it will kill the lawn.

Drive XLR8 is a tried and true method of control that when applied correctly, is extremely effective. 

Lastly, Spectracide Weed Stop is a great weed control product that controls over 250 various types of weeds and easily hooks up to the end of your garden hose.

If nothing else works, spot-treat the weed with a non-selective herbicide.

This is often a last-resort option and should be optional. If you’ve applied both a pre- and post-emergent herbicide and still see outbreaks, consider spot-treating it with a non-selective herbicide. 

Non-selective herbicides will kill any and all vegetation it comes in contact with, which is why you should spot-treat it. You’ll use a liquid non-selective herbicide, tank-mix it in a spray-tank and apply directly to the weed with a nozzle.

Selective herbicides, on the other hand, only kill the weeds listed on their product labels.
When it cannot be controlled by maintenance practices alone and a chemical must be applied, make sure to read the label carefully to ensure that it will not cause any damage to your lawn and is compatible with your type of grass.

Non-chemical control

There are many control options available to help ensure that this season is the last time it invades your lawn. Some natural prevention methods to strengthen your lawn include:

  1. Raising the mowing height: This will help keep the soil cool by keeping the sunlight out, making it more difficult for it to germinate and take over.
  2. Watering deeply once a week: Avoid light irrigation that would allow weed seed to germinate, and make sure your lawn is well watered and healthy before germination begins.
  3. Avoid fertilizing in the summer: Make sure fertilizer is applied before the weed begins germinating. This will keep your lawn thick and give it the upper hand.
Close Up Of Mower Setting Wheel
Can you pull it?

Yes, you can pull it by hand and with a small garden shovel. It can be hard to remove, so watering the soil around it might make it easier to pull the weed. The only risk with this is that they must be pulled early in the season before it has enough time to produce a bunch of seed.

With that being said, it’s also better to pull it if it’s younger. Larger, established plants have seed heads that will drop into the soil and grow more in its place.

Where does it grow?

It’s a strong weed. It can be found in any type of grass including zoysia, bermuda grass, St. Augustine, centipede, fescues and others.

Additionally, you can spot this weed in lawns, athletic settings, commercial landscapes, gardens and more. It likes to grow in hot, dry conditions with poor soil quality and easily takes over lawns that are heat stressed.

What causes it?

As previously mentioned, it prefers warm, dry environments with poor soil quality. Mowing the grass too low can encourage its growth in addition to light watering.

How does it grow?

It spreads and reproduces by seed. It can produce up to 150,000 seed per plant. Mowing over it can also spread the seed it produces throughout other areas of your lawn.

When does it germinate?

This ultimately depends on your geographic location. It usually begins germinating in the late spring and early summer after the soil temperature has reached a temperature of 55 to 60 degrees for over five days. 

When does it die?

It’s an annual, meaning the same plant won’t keep showing up year after year. It typically dies when colder weather ensues and once it’s been hit by a frost. 

How to get rid of it in the summer

The best way to get rid of the weed in the summer is to remove it by hand. This can be risky if the plant is mature with a lot of weeds. Once it is pulled, follow up by planting seed or grass plugs in the open area so that more weeds don’t invade. 

Water the lawn deeply 1–2 times a week, as it doesn’t prefer moist environments. Mowing at a taller height also discourages remaining seed growth.

It’s highly recommended to not apply any sort of weed control chemical during the summer because it can burn and damage your lawn. However, carefully spot-treating it with an effective post-emergent without letting the chemical touch the grass will also kill it in the summer. To be super safe, consider surrounding the plant with some sort of barrier to prevent it from making contact with your lawn.

With either method, be sure to apply a pre-emergent come next spring to prevent future growth.

How to kill it in the spring

Apply a pre-emergent in early spring to prevent it from growing. Read more about application dates here. Use a post-emergent on any currently existing weeds.

How can it be prevented?

Pre-emergent herbicides are used to prevent weeds from appearing.

Use pre-emergents before the first frost in your area in the fall and before soil temperatures reach 70 degrees Fahrenheit.

Additionally, maintaining a healthy lawn with good-quality soil and proper mowing heights will discourage growth. Watering the lawn regularly so that the soil doesn’t get too dry will also discourage growth. 

When is the best time to apply crabgrass preventer?

This depends on where you’re located. Refer to the map below for exact application dates for prevention.

Pre-Emergent Application Dates for Spring

To learn more about identifying what kind of weeds you may have in your lawn so that you know how to best remove them, check out our Identifying Common Lawn Weeds blog. For more information on weed control in general and the best ways to reduce weeds, visit our Weed Control blog.

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