Crabgrass is a common and stubborn weed that can invade lawns and gardens. Getting rid of crabgrass takes some effort, but is possible with the right techniques. Here is a comprehensive guide on how to rid your lawn of crabgrass and restore a lush, weed-free turf.
Identifying Crabgrass
Crabgrass is an annual grassy weed with long sprawling stems that root at the nodes. The leaves are light green with hairy, rounded tips. Crabgrass spreads rapidly via its stems that root wherever they touch the ground. It sprouts in spring and dies back in autumn after setting seed.
Here are some identifying features of crabgrass:
- Sprawling growth habit with stems radiating from a central root
- Coarse, wide light green leaves with rounded, hairy tips
- Fast spreading through stems that root at nodes
- Seeds profusely, leaving behind dead browning patches
- Grows actively in summer, dying back in fall/winter
Preventing Crabgrass
An ounce of prevention is worth a pound of cure when it comes to crabgrass control. Here are some effective ways to prevent crabgrass from invading your lawn:
Maintain a Thick, Healthy Lawn
A lush, dense lawn is the best defense against crabgrass. Follow good cultural practices like proper mowing, fertilization, aeration and adequate irrigation to maintain vigorous turfgrass growth. This leaves little room for crabgrass to establish.
Use Crabgrass Preventer
Applying pre-emergent herbicides or crabgrass preventers before crabgrass seeds germinate in early spring can create a chemical barrier to block growth. Products with active ingredients like prodiamine, dithiopyr or pendimethalin are effective options.
Proper Mowing Height
Mow your lawn no shorter than 3 inches tall. This shades the soil and inhibits crabgrass growth which thrives in thin, sparse turfs.
Water Infrequently But Deeply
Crabgrass flourishes when the topsoil is constantly moist. Instead, water your lawn deeply and infrequently to encourage deeper rooting of desirable grass.
Overseed Bare Spots
Any thin, bare areas or spots that were damaged over winter should be filled in by overseeding with grass varieties suitable for your climate. This prevents crabgrass from occupying those spaces.
How to Get Rid of Existing Crabgrass
If crabgrass has already established itself in your lawn, here are the most effective ways to get rid of it:
Hand Pulling
For young crabgrass plants with shallow roots, simply pulling them out by hand is the quickest way to get rid of them. Try to remove as much of the root system as possible. Best done after rainfall when the soil is moist and roots pull out easily.
Cultivate and Reseed
Use a tiller or power rake to aggressively cultivate areas overrun by crabgrass. This brings up the entire root system which can then be raked up and discarded. Follow by reseeding with desirable grass seed once soil temperatures cool down in early fall.
Post-emergent Herbicide
There are crabgrass-specific post-emergent herbicides containing quinclorac, fenoxaprop, mesotrione or sulfentrazone that will selectively kill crabgrass while leaving your lawn unharmed. Apply per label instructions for your grass type.
Spot Treat with Vinegar
For isolated crabgrass plants, use a foam paintbrush to wipe full strength white or horticultural vinegar directly onto leaves. Repeat every 7-10 days until plants are completely dead. Vinegar kills indiscriminately so avoid contact with wanted plants.
Solarize Infested Areas
Cover areas densely infested with crabgrass using clear plastic sheeting for 4-6 weeks over summer. The heat generated under the plastic kills crabgrass seeds and plants. Reapply crabgrass preventer and reseed treated areas in fall.
FAQs about Crabgrass Control
How do I know if I have crabgrass in my lawn?
Look for light green patches of fast spreading grass with hairy, rounded leaf tips. Stems will radiate out in a sprawling pattern from a central root. Plants root from the nodes and spread rapidly.
When is the best time to apply crabgrass preventer?
Timing is critical for crabgrass preventers to be effective. They must be applied and watered in before crabgrass seeds have a chance to sprout – which is early spring right around the time of forsythia bloom.
How long does it take to kill crabgrass with vinegar?
It typically takes 2-4 applications of horticultural vinegar sprayed directly on the crabgrass foliage to fully kill it. Treatments should be made every 7-10 days until the plants are completely dead.
Can I spot treat crabgrass with herbicide?
Yes, many selective post-emergent herbicides are formulated to selectively kill crabgrass when sprayed directly on infested areas. This avoids exposing the entire lawn to the chemical.
Should I dig out clumps of crabgrass or spray them?
For large clumps, it’s best to dig out as much of the root system as possible. Any remaining plants can then be spot treated with herbicide. Removing clumps prevents re-seeding.
When is the best time to reseed after crabgrass removal?
The ideal window is early fall when soil temperatures start to cool but before the first frost. Crabgrass will be dying out while cool season grass planted at this time will establish before winter dormancy.
Conclusion
Eliminating crabgrass from your lawn takes commitment, but is definitely achievable. A proactive defense focused on good maintenance, proper mowing, pre-emergents and turf thickness is key for prevention. For existing infestations, mechanical removal combined with selective herbicides or non-chemical controls like vinegar works well. Reseed treated areas in fall to restore a lush, crabgrass-free lawn. With vigilance and persistence, you can rid your yard of crabgrass for good.