How can you get rid of crabgrass in your yard? Your options include pulling the plants at their roots, applying weed killers, or turning to lawn care professionals. No matter what method you choose, you may face an ongoing battle.
Crabgrass — at first, it seems like nothing but an oddly colored blade here or there, poking up among the otherwise rich green turf. Then, as soon as you let your guard down, you realize it’s a full offensive. The crabgrass has arrived to sabotage your immaculate landscaping. (OK, maybe not immaculate…)
Before the invasion takes over, there’s a lot you can do in the fight against crabgrass. After you’ve launched your counterattack — whether by hand-to-hand combat (weeding) or chemical warfare (applying weed killers), or calling in reinforcements (hiring a professional) — the crabgrass will retreat, and your lawn will again rank as one of the best in the neighborhood.
What is Crabgrass?
Crabgrass is a summer annual weed that favors compacted soil where the grass is in a thinned and weakened condition. During the early spring, crabgrass germinates when soil temperatures are between 55 and 65 degrees, about 3 inches below the surface. Once midsummer hits, growth slows, it begins to set seeds, and dies off with the first frost.
With coarse, yellow-green leaves, this weed is easy to spot among the green, fine leaves of turf. Crabgrass grows in bunches, like the arms of a crab or like troops spread out across a battlefield.
The real concern is the crabgrass growth cycle. A single plant produces as many as 150,000 crabgrass seeds. And these seeds can lie dormant for as long as 30 years.
What this means: Each growing season is just one battle in the ongoing war against crabgrass.
With proper planning and preparation, it is possible to be victorious against crabgrass. While it’s unlikely you will ever totally sign a peace treaty with this weed, you can control crabgrass and come out of this fight on top.
Read on for your tactical training.
How to Get Rid of Crabgrass
Weeding (On-the-Ground Combat)
Pulling the individual crabgrass plants can be a helpful plan of attack. Getting crabgrass out at its root level is one of the surest ways to kill crabgrass, but it is tiring and takes time and patience.
Unfortunately, maintaining crabgrass weed control means regularly weeding your lawn.
When to attack: Weeding should be done in late spring, before the crabgrass plant grows large and distributes its seeds. As with all weeding, this job is easiest following a rain when the soil is moist and soft.
Apply Weed Killers (Chemical Warfare)
A common choice for any weed issue is a topical application. You’ll find lots of options at your local home store, but not all herbicides are created equal. Here’s a bit of information to help you in your advancement on crabgrass.
It’s important to choose a selective product, as it will attack certain weeds without permanently damaging the surrounding grass. You also need a product targeting invasive grasses; crabgrass is a grass, not a broad-leaf weed.
There are two main types of weed killers: Pre and post-emergents.
Pre-emergents are preventative chemicals that work to interrupt weed germination and prevent weeds from sprouting in your lawn.
Post-emergents are the chemicals to use after weeds have already sprouted. Post-emergents will kill the already grown weeds on your lawn.
Finally, liquid and granular options work equally as well. However, liquid products require a calibrated sprayer. It’s unlikely you already have a sprayer in your toolshed, but out in that cache of tools is probably a spreader. This alone might make granular options your best route.
After application, be sure to water according to the product’s instructions.
Post-Emergent Weed Killers: Once crabgrass has staked its claim and is sprouting in your yard, it’s time to diversify your arsenal. Post-emergent herbicides target the plant itself, killing it before it has the opportunity to produce more seeds.
Stay away from “weed and feed” varieties, which combine herbicides and fertilizers. Because crabgrass is a variety of grass, these applications will actually nourish the invaders. Look for selective, post-emergent products specifically targeting crabgrass.
Always read product labels carefully; ensure your grass type is listed as approved. More importantly, though, is to read and follow all safety directions. These are chemicals, and while they can be helpful in achieving landscape victory, they also can be dangerous.
How to Prevent Crabgrass
A Healthy Lawn
Your best defense against crabgrass and other lawn weeds is as simple as a healthy lawn. The shade created by a dense turf will prevent seeds from germinating, giving you an automatic advantage in the fight. There are a few ways to encourage a healthy lawn and discourage crabgrass.
Aeration: Crabgrass favors compacted soil, so aerating the lawn is a sure way to help keep your lawn healthy and prevent crabgrass. Aeration helps to increase airflow in the soil and allows for more water accessibility. Grassroots will be stronger this way, and crabgrass is less likely to appear.
Topdressing: If you’re looking for organic ways to improve the health of your lawn, look no further. Topdressing is a technique that involves spreading material such as sand or compost over the top of the grass to improve the soil quality. By improving your soil, you improve the health of your grass, making it easier to fight off weeds such as crabgrass.
- Pro Tip: Pair this with overseeding to give your lawn an extra boost.
Mow tall: Trim your grass blades to the highest recommended height. Regular mowing serves as a natural crabgrass preventer, choking many weeds.
Water infrequently: You’ll also want to water deeply but infrequently; this will kill the shallow-rooted enemy as the top of the soil will dry out in between waterings.
Plant at the right time: If you live in a colder region, fall is the best time to overseed. For warm-season grasses, plant new grass seed in late spring or early summer. When seeding bare spots, water regularly. Apply a crabgrass preventer in the spring. (Check the label if you want to apply a pre-emergent before planting new grass seed. Most pre-emergents also prevent new grass from germinating.)
- Pro Tip: One common misconception is that cutting crabgrass short will kill it off quickly. This little villain can produce seeds even at just 0.5 inches tall, which is much shorter than any residential lawn should be mowed. Like with most weeds, it’s important to get the roots and get them early.
Corn Gluten Meal
Corn gluten meal (CGM) is a natural pre-emergent that won’t harm your grass. This natural material is a byproduct of corn and can be used to prevent some grassy and broadleaf weeds from sprouting, including crabgrass. The proteins in CGM slow seedlings’ roots while also adding nitrogen to support turf growth and further help crabgrass control.
Corn gluten meal needs to be applied liberally and evenly to get rid of this weed. It is recommended to use 20 pounds per 1,000 square feet. Once it’s been spread out, water it into the soil.
Pre-Emergent Weed Killer
Pre-emergent weedkiller is the most effective and economical tool in the struggle with crabgrass. Pre-emergent herbicides interrupt the growth process, preventing complete germination. In other words, these pre-emergents prevent crabgrass seedlings from ever seeing the light of day.
These products should not be used on grass that hasn’t established itself. For best results, overseed in the fall, and apply a pre-emergent in the spring before the crabgrass has a chance to germinate.
Note: Timing is critical when it comes to applying pre-emergents in the spring. Consider soil temperatures before you start to spray a pre-emergent. These herbicides work best when the soil (not air) temperature is between 50-55 degrees. If you apply too late, they will not interrupt the germination of the seedlings.
Look for products with these active ingredients:
- Dithiopyr
- Prodiamine
- Oryzalin (works especially well on warm-season grasses)
FAQ About Crabgrass
Aside from using natural techniques like ripping out the weeds or corn gluten meal, there are selective herbicides that won’t kill certain grass types.
• Post-emergent herbicides such as quinclorac and foramsulfuron are known crabgrass killers and work on certain grasses but can harm others. Using chemicals to kill crabgrass, not the green grass you want in your yard, involves knowing your grass and reading the labels of herbicides.
Quinclorac will not harm bermudagrass, Kentucky bluegrass, or tall fescue lawns, but should not be applied to bahiagrass, centipedegrass, fine fescue (unless it’s part of a fescue blend), or St. Augustinegrass.
Foramsulfuron works for bermudagrass and zoysiagrass, but should not be applied to cool-season turfgrasses, St. Augustinegrass, or centipedegrass.
• The best way to get rid of crabgrass is to take care of your lawn. Having a healthy lawn prevents crabgrass from growing and saves you from killing your grass. Make sure to aerate and topdress annually to break up compacted soil, overseed to fill in bare patches, and mow tall to shade the soil and prevent crabgrass from germinating.
Hand-pulling or using selective post-emergent herbicides are the fastest ways to kill already established crabgrass. On very small crabgrass seedlings, one treatment of horticultural vinegar is also usually effective.
Many homeowners don’t want the risk that chemical herbicides bring to their healthy grass which is why they choose these natural preventative steps instead:
• Keeping a healthy lawn can involve aeration, topdressing, overseeding or reseeding, proper mower heights, and watering.
•Corn gluten meal is a natural remedy and byproduct of corn. It is used to contain all broadleaf weeds and supports and strengthens turf growth in the process.
Hire a Professional (Call in Reinforcements)
Sometimes, when your weed control plan is getting less than controlled, the best thing to do is bring in backup. In this case, backup means lawn care professionals who can mount a strategic offensive on all fronts. Once you’ve exhausted all of your options and your lawn is about 60% crabgrass or other weeds, it’s time to call on the allied forces.
Main image credit: Wikimedia Commons / CC by SA 3.0
