Crabgrass is an aggressive weed that appears to sprawl like crab legs, and many homeowners hate how it disrupts the uniformity of an otherwise lush lawn. When left untreated, it can compete with the grass for nutrients and water, and spread into garden beds, and affect plants. Eliminating crabgrass can seem like a daunting, never-ending chore, but with the right approach, you can win the battle. Start by realizing that crabgrass is a common weed that's most prolific in the summer. It thrives in hot, dry conditions at times when the rest of your lawn may struggle. To effectively and efficiently eradicate crabgrass, follow these steps:
- Identify crabgrass seedlings early. Crabgrass is a light green, low-growing weed with a sprawling habit. It typically appears in bare or thin spots of your lawn, but we also see it popping up in our mulched garden beds. It's easiest to identify in the early stages of its growth, usually in the late spring to early summer.
- Prevent crabgrass growth using a pre-emergent herbicide. Apply a pre-emergent herbicide in early spring, before the crabgrass seeds germinate. This creates a barrier in the soil that prevents the seeds from sprouting. As you choose a herbicide, note that crabgrass is not a broadleaf weed, but it does produce thousands of seeds and regrows every year if not eradicated. A thick, healthy lawn can crowd out weeds and reduce crabgrass germination, so prioritize proper lawn maintenance, too. Make sure your grass roots are well-watered and fertilized, and that the blades are mowed at the correct height.
- Manually remove the crabgrass sprouts. This is the most organic method, in my experience — more effective than boiling water, corn gluten meal, and gardening vinegar. For small crabgrass infestations, I have the most luck manually pulling the crabgrass plants by bundling the sprawling stems and yanking up to expose the roots. Removing the full root system is essential to preventing regrowth. You can also use specialized weeding tools for more efficient removal, especially for larger patches.
- Apply a post-emergent herbicide. Use a product specifically formulated for crabgrass, and importantly, make sure it’s safe for your type of lawn. Follow the manufacturer’s instructions for application. Typically, these products are most effective when applied to young, actively growing crabgrass.
- Keep up with ongoing lawn care. Keep your entire lawn mowed to an appropriate height for your grass type. Avoid cutting the type of grass more than one-third of the grass blade at a time. Maintain a frequent watering and fertilizing schedule to promote a crabgrass-free lawn that can resist invasive weeds.
When is the best time to apply pre-emergent herbicide?
The best time to apply a pre-emergent herbicide, such as Scotts, is in early spring, before the crabgrass seeds begin to germinate. This is usually when soil temperatures reach around 55 degrees Fahrenheit. Applying it too late will not prevent the annual weed seeds from sprouting.
Can I reseed or overseed my lawn after using a pre-emergent herbicide?
Yes, but timing is important. Most pre-emergent herbicides from garden centers will prevent all seeds from germinating, including grass seed. Typically, you should wait about 8-12 weeks after herbicide application before reseeding. Check the herbicide’s label for specific recommendations.
