Last summer, my sister mentioned that her lawn looked lumpy and weird. She asked me if she needed to level it or what she could do to get that lush, even look she wanted. I went over to take a look, and sure enough, her lawn was uneven—not because it needed leveling, but because crabgrass had taken over. Luckily, I know all about how to kill crabgrass and showed her exactly what to do to tackle the problem head-on. Crabgrass can be a persistent beast, but with the right approach, you can take control of it just like any other weed.
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What Is Crabgrass?
Crabgrass is light green grass that grows low to the ground in a clumpy, sprawling pattern. The rough blades are thicker and wider than the smooth, thin blades of most lawn grasses. One sign that you have crabgrass is that the grass blade has a ridge, or midrib, running down the center.
Crabgrass fans out from a central root, almost like fingers, and loves sunny spots. Once the soil warms up to around 55–60°F, you’ll start to see clumps of crabgrass popping up. By mid-summer, it can take over your whole lawn if you don’t kill or remove the crabgrass.
Best Way To Kill Crabgrass
Once crabgrass establishes itself, taking quick action is your best ally. Knowing what kills crabgrass and acting promptly can save your lawn. Here are the most effective ways to tackle it:
Apply Pre-Emergent Herbicides
The best way to prevent crabgrass is to stop it before it even starts. Use a pre-emergent herbicide in early spring, before the seeds can sprout. Pre-emergents work like a barrier to block weeds from growing. Timing is everything, though, so keep an eye on the weather and apply the pre-emergent when the soil hits around 55°F consistently.
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Use Post-Emergent Herbicides
If crabgrass has already sprouted, a post-emergent herbicide can target it directly. Look for products containing quinclorac or fenoxaprop, which are designed to kill crabgrass without harming most lawn grasses. Avoid glyphosate, though—it’s non-selective and will kill any plants it touches.
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Manually Remove Crabgrass
For smaller infestations, pulling crabgrass by hand is a straightforward option. The key is to work when the soil is moist, which makes it easier to pull the plant and its roots out completely.
How To Prevent Crabgrass From Growing
Preventing crabgrass from growing is often easier and more effective than trying to kill it once it’s established. Here’s how to keep crabgrass at bay:
- Fertilize Your Lawn: Fertilizing your lawn provides the nutrients it needs to grow thick and strong, naturally crowding out crabgrass by shading the soil and leaving no room for weeds.
- Trim Your Grass: Mowing to the right height (around 2.5–4 inches, depending on the type) keeps your grass healthy while also reducing the chance of crabgrass seeds germinating, as mowing disrupts their ideal growing conditions.
- Water Deeply (but Infrequently): Watering deeply encourages strong, deep roots in your grass, while shallow watering creates the perfect environment for weeds like crabgrass.
- Aerate Annually: Aerating your lawn loosens compacted soil, making it easier for water, air, and nutrients to reach your grass roots—keeping them strong and crowding out weeds.
Kill Crabgrass and Enjoy a Weed-Free Lawn All Year
Crabgrass might be tough, but it’s no match for a solid plan. By learning how to kill crabgrass, you can reclaim your lawn and keep it looking thick and healthy. Just like I helped my sister transform her patchy, crabgrass-filled yard, you can take the right steps to prevent and control crabgrass for good.