Crabgrass is one of those grasses that grow in tough conditions. This makes it a bad weed for homeowners who want to grow thick, lush and green lawns. All the methods that we’ll apply to kill crabgrass will take into account that this weed flourishes in both warm and cool weather conditions.
The best way to kill crabgrass in your lawn is to apply a selective post-emergent crabgrass killer. It will remove the weed while leaving your lawn grass alive. Other safe methods include using natural killers such as baking soda and vinegar.
Timing to Get Rid of Crabgrass for Good
Crabgrass is a grass just like other grasses in your lawn. Applying combination herbicides won’t get rid of it. Of importance to note is that timing is important if you want to get rid of this weed permanently.
There’s a big difference between controlling perennial grass weeds and annual grasses. Annual and bi-annual grass weeds have a period of dormancy while crabgrass thrives all year round. That is why it is a perennial weed.
Crabgrass will thrive even in winter (November – April) when most lawn grasses are dormant. Here are two timing tips that will help you get rid of crabgrass in your lawn:
- For spring, just before germination of this weed, apply a pre-emergent herbicide. This will prevent the seeds from germinating in your lawn.
- In the summer, use a potent crabgrass post-emergent herbicide to kill already existing weeds in your lawn.
As you can see, understanding the life-cycle of this lawn weed is key to eliminating it for good. Here’s a summary of what you need to keep on your calendar to control this weed.
|Spring||Soil temperature = 55 – 60 degrees Fahrenheit. Crabgrass seeds germinate||Apply a pre-emergent herbicide for crabgrass control.|
|Mid-summer – Fall||Warm weather; crabgrass is flowering and producing seeds.||Apply a post-emergent herbicide, or uproot.|
|Winter||Cold temperatures, dormant crabgrass seeds.||Prepare to apply a pre-emergent.|
How to Kill of Crabgrass in Lawn
The best, natural way to get rid of crabgrass and perennial weed grasses is to dig them out rather than spraying them with Roundup or other herbicide of your choice. But that’s not the only way. Below, I’ve detailed different ways to eliminate this weed using organic methods as well as chemical methods.
1. Pull out the crabgrass
Even if you use a herbicide to kill crabgrass weed, you’ll still have to dig it out to completely get rid of it. But using a chemical is not really one of my favorite methods because it has detrimental effects on the surrounding lawn grasses.
I prefer removing crabgrass naturally, which involves digging it up. It is a great way of eliminating the weeds without killing lawn grass. Here’s a simple way to pull out this weed:
- Water the spots with crabgrass for about 30 minutes to soften the soil.
- Use a claw weeder or a pitchfork to uproot crabgrass. You can also use your hand if there just a handful of spots infested.
- Add rooting fertilizer or organic manure to the area.
- Reseed the bare spot in your lawn with good grass seed to regrow grass.
- Care for the new grass as usual.
Early in the spring, the shoots of crabgrass are still small. You can pull them out of your lawn and manage to get rid of them successfully unlike in the summer when the weeds are extensively grown.
Crabgrass has a crab-like root system. While it’s easier to uproot, you may want to use a claw weeder to make your work a lot easier. It uproots invasive weeds including crabgrass, dallisgrass, dandelions etc.
My favorite claw weeder is the Fiskars 39″ 4-Claw Weeder. (Click the link to see a video of how it works on Amazon).
Digging and uprooting can also cause a little damage to your lawn, so be careful not to end up with a sodding job to do especially if there are extended areas invaded with crabgrass.
2. Sponging with Roundup
Sponging is a great chemical technique for killing crabgrass and other perennial grasses in your lawn. It is different from spraying because you don’t want to affect the good grasses in your lawn.
Here’s how to kill crabgrass by sponging:
- Mow around the crabgrass for about 2 weeks to allow the weed to grow taller than your lawn.
- Put some amount of Roundup herbicide in a bucket and mix with a surfactant or sticking agent.
- Dip a sponge in the Roundup and lace the top part of crabgrass (2-3 inches of the grass blades).
- Repeat this process 2 to 3 times over the course of two weeks to allow the herbicide to kill the entire weed.
With sponging, the glysophate in Roundup goes underneath and travels all the way down the grass weed, killing it. Glysophate is a non-selective herbicide that can easily kill perennial weeds as well as your lawn grass.
To get rid of crabgrass without killing lawn grasses such as Bermuda grass or St. Augustine, ensure that you don’t apply too much Roundup. If you do, you’ll end up with a ring of death around the area you applied the chemical.
3. Apply a Crabgrass Killer
Post emergent crabgrass killer
Scotts crabgrass killer
4. Use baking soda
5. Apply corn gluten
6. Use vinegar to kill crabgrass
How to Control Crabgrass (Prevention Options)
Timing is key when it comes to controlling and preventing crabgrass in your yard. From experience, if you wait too long, the weed will take root and you’ll find it hard to control it.
Here are 3 great ways of controlling crabgrass in your lawn:
Put down pre-emergent on time
What you want to do is control crabgrass early in the season, probably during the second mowing or so. During this time, you can use a crabgrass control product, usually called a pre-emergent or preventer. See my guide and tips on the best time to put down a crabgrass preventer.
I usually recommend choosing a crabgrass pre-emergent that contains fertilizer in it. One of my preferences for this is Vigoro Crabgrass Preventer and Lawn Fertilizer.
If you opt to try this product, ensure you choose one that contains time-release nitrogen in it to prevent burning out your precious lawn.
Overseeding Your Lawn
Overseeding is one of my favorite techniques for weed control and keeping my lawn lush green and thick. It is a simple technique of planting grass seed directly into the existing turf without having to go through the normal preparation procedures.
The result of an overseeded lawn is a thick, dense lawn and filled-up bare spots. But how does that control crabgrass weeds?
- The thick lawn grass chokes out any existing crabgrass, thus killing it naturally.
- An overseeded lawn prevents crabgrass from germinating, thus controlling it a lot more effectively.
You can overseed your lawn in either the fall or early spring, allowing the grass enough time to germinate and grow before the crabgrass starts growing in the summer.
Grow a thick, healthy lawn
Nothing beats a healthy, thick lawn. Even weeds struggle to germinate and outgrow a lawn that’s thick and dense. If there are any crabgrasses germinating in your lawn, you can choke them out easily especially early in the season with a thick lawn. But how do you make your lawn dense?
Here’s how to grow a thicker lawn and choke out crabgrass weeds:
- Water your lawn only once a week to promote a deeper, stronger root system. Watering more than once makes your lawn develop weaker roots, making it more vulnerable to tenacious grass weeds.
- Mow your lawn higher than you’re used to. It is recommended that you leave your lawn 2 – 3 inches higher to crowd out crabgrass and prevent it from growing.
- Aerate your lawn at least once a year. This is especially good for turfs with clay soil in them. Lawn aeration will help improve oxygen circulation and promote a healthier, thicker lawn.
- Fertilize your lawn enough especially if it is Bermuda grass. However, you want to use a time-release nitrogen fertilizer in order to control weed growth.
- Reseed or overseed in the fall to prevent crabgrass. But why in the fall? Fall is a season of warm days and cool nights. This will promote healthy growth of lawn grass especially when there’s dew in the morning.