Ways To Prevent and Kill Crabgrass
This article includes information regarding organic and synthetic options, pre-emergent vs post-emergent, solutions for warm and cool-season grass and more.
Everyone knows crabgrass is hideous, but few know how to control and prevent it. A single crabgrass plant can produce 150,000 seeds – here’s how you can keep this menace out of your lawn.
The old phrase “The best defense is a good offense” carries a lot of truth in lawn care. Overseeding with your desired grass type can stop crabgrass from even getting started. Not only will overseeding improve the overall aesthetic by thickening the lawn, but it will provide some good competition for this and other types of weeds.
Pre-emergent is a type of herbicide that stops crabgrass from sprouting. “Tenacity” is one of the best pre-emergents (active ingredient mesotrione). The great thing about Tenacity is that it will not hinder desired grass seed from germinating: it stops the crabgrass, not the good grass. You can apply Tenacity and overseed to get the best of both worlds.
The trick with Tenacity, and all pre-emergents, is timing. It will only remain active for several weeks. Since crabgrass starts to germinate in warmer weather, it is generally best to apply Tenacity in the late spring.
Be sure to double-check the label; Tenacity is not recommended for some warm-season grasses.
What if I have crabgrass now?
Fret not, dear reader. There are solutions for you too. Tenacity will also work as a post-emergent, meaning it will kill crabgrass after it has already sprouted. However, Tenacity is a bit pricey. If you are at this point, there are more economical options available that are just as effective.
“Ortho Weed B Gone Plus Crabgrass” lives up to its name; it will kill it and many other weeds. The active ingredient that kills is Quinclorac. It can take a couple of weeks to see results, but it works. It may turn the crabgrass red or purple while it’s working.
There are a couple of downsides with Ortho Weed B Gone Plus Crabgrass. It can not be used when temperatures exceed 90 degrees. In this hot weather, the herbicide will evaporate and not be effective (called vapor drift for the horticulture nerds out there.) It will also kill some warm-season grass; be sure to double-check the label.
After the pre-emergent has done its job, it will leave a bare spot on your lawn. Be sure to patch with some grass seed or plugs, otherwise, a new weed will move in.
I have warm-season grass. Thanks for nothing!
Not to worry, there are solutions for those of you who have Centipedegrass or Saint Augustine lawns. “Spectracide Weed Stop For Lawns For St. Augustine & Centipede Lawns” will work as a post-emergent solution. (Active ingredient atrazine). Like Quiclorac, this product must be applied when temperatures are below 90 degrees to be effective.
If you’re looking for a pre-emergent option, use “Bonide Crabgrass & Weed Preventer for Lawns & Ornamental Beds.” (Active ingredient dithiopyr). It has a long list of weeds it prevents in addition to crabgrass. It can also be used in the fall to prevent winter annual weeds (like henbit or poa annual). With all pre-emergents, timing is critical. It needs to be applied before the weeds start popping up.
With crabgrass, there aren’t solutions that are organic, effective, and easy. If you are willing to put in a little extra work and have some patience, here are some organic solutions:
Pull by hand
Hand pulling weeds has been around as long as there has been agriculture. Crabgrass can be particularly stubborn and is likely to return after hand pulling. To be successful, you must be diligent. A couple of times a week you should do a “weed walk” and pull any new growth of crabgrass. In time, the weed will run out of energy and be unable to produce new growth tissue. Hand pulling will work if you follow through.
This option requires less diligence but can leave an eyesore for a while. Simply pull the crabgrass, and leave a heavy object in its place like a rock or a brick. The crabgrass will not be able to push up the brick and die in a few weeks. Make sure the object is wide enough so the crabgrass can’t grow horizontally to evade it. Afterward, fill in the dead spot with new grass seed or plugs.
Vinegar can work for crabgrass, but it comes with a lot of catches. First, it needs to be 20% acetic acid. This means the Vinegar you use for cooking won’t work too well, and this strength of vinegar will need to be specially ordered (easy to find online.)
Next, you’ll need to mix the vinegar with a surfactant. To keep things organic, orange oil works well. You only need 1 part orange oil to 100 parts vinegar. This solution is 96% effective according to the USDA. However, it will also kill your desired grass. Be very careful when applying, and be prepared to follow up with overseeding or patching.
Corn Gluten Meal
Corn Gluten Meal has been reported to be an effective pre-emergent against crabgrass. However, this is widely disputed by the academic community. Nonetheless, there are many lawn enthusiasts and professional landscapers who swear it works. The good news is that if you want to give it a try, it is relatively cheap. Just know that this option is more of a gamble instead of a guaranteed solution.
Hire a Professional Landscaper
Although hiring a landscaper may come at a cost more than a DIY project, in the long run, they can save you money when your time is involved, plus the stress that comes along with it.
By hiring Fernandez & Sons Masonry and Landscaping services you can rest assured your weed-filled lawn will be beautiful and weed-free. Contact Fernandes & Sons today to get the help you need. We look forward to hearing from you and helping you.