Does your beautiful green lawn suddenly sprout ugly, coarse patches of crabgrass? It feels like a losing battle, doesn’t it? You see those spiky invaders popping up, and you know you need to act fast before they take over your yard.
Choosing the right crabgrass killer can feel overwhelming. Should you use a pre-emergent to stop seeds before they sprout, or a post-emergent to zap the existing weeds? Different products work better at different times, and using the wrong one wastes time and money. Nobody wants to spend their weekend spraying chemicals that don’t work!
This guide cuts through the confusion. We will break down exactly what you need to know about the best lawn crabgrass killers available today. You will learn the difference between preventative sprays and spot treatments so you can finally conquer this persistent pest.
Keep reading, and let’s transform your yard from crabgrass chaos to a perfectly manicured carpet.
Top Lawn Crabgrass Killer Recommendations
- Weed killer for lawns: Kill weeds in your lawn, including dandelion, chickweed, clover, crabgrass and foxtail with the Ortho WeedClear Lawn Weed Killer Ready-to-Spray
- Fast-acting weed control: This weed control product kills listed weeds like crabgrass, dandelion, clover, chickweed and creeping charlie down to the root and gets results with 1 application
- Broadcast treatment for weeds: Won't harm lawn grasses when used as directed - use on lawn grasses including Bermudagrass, Buffalograss, Fescues, Kentucky Bluegrass, Ryegrass and Zoysiagrass
- Spray weed killer: Apply to weeds that are young and actively growing by connecting your garden hose to the sprayer, sliding the switch to "ON" and spraying evenly until the lawn is wet
- Ready to spray: This 32 oz. container of Ortho WeedClear Lawn Weed Killer Ready-to-Spray treats up to 5,000 sq. ft.
- ALL-IN-ONE FORMULA: BioAdvanced's All-in-One formula kills listed lawn weeds and crabgrass without harming the lawn
- KILLS TOUGH WEEDS: Control over 200 broadleaf weeds like dandelion, clover, and crabgrass using our powerful weed killer concentrate
- DOWN TO THE ROOT: BioAdvanced All-In-One Lawn Weed and Crabgrass Killer I penetrates and removes tough listed weeds down to the root
- RAINPROOF IN ONE HOUR: Our weed killer concentrate formula is rainproof in one hour, providing protection that wont wash away
- EASY-TO-USE CONCENTRATE: Easily apply with our concentrated formula, perfect for targeting weeds in your lawn, and compatible with various grass types
- Water-Based Formulation: Experience the power of our unique water-based formulation that ensures superior control and faster plant uptake, delivering results you can see quickly
- Extended Residual Control: Enjoy up to 30 days of residual control, keeping your turfgrass free from troublesome weeds for longer periods and reducing the need for frequent applications; Rainfast in less than an hour
- Broad-Spectrum Weed Control: Effectively targets a wide range of weeds, including crabgrass, foxtail, kikuyu grass, signal grass, torpedo grass, and key broadleaves like bindweed, clover, dandelion, black medic, and horseweed
- Versatile Application: Perfect for residential lawns, golf courses, commercial properties, and other non-residential turfgrass sites. It is labeled for use on both warm-season and cool-season turf types, ensuring adaptability to various environments; See label for proper mixing instructions
- USE AS INTENDED: Read, understand and follow label safety and application instructions; Follow proper storage and disposal instructions; NY can only be applied as a spot application; Proper PPE required long sleeve shirt, long pants, socks and shoes, chemical resistant gloves; See label for environmental hazards; State restrictions may apply
- WEED PREVENTION: Scotts Halts Crabgrass & Grassy Weed Preventer prevents the germination of listed lawn weeds so you can enjoy your lawn
- CRABGRASS PREVENTER: Prevents the germination of crabgrass, foxtail, spurge, barnyardgrass, and more as listed in the early spring all season long, and moss (except in California), Poa annua, henbit, corn speedwell, and chickweed in the fall
- APPLICATION: Apply this pre-emergent weed and crabgrass killer in the early spring to a dry lawn or in the fall; rain, snow, or freezing weather after application will not affect the performance of this lawn care product
- GRASS TYPES: This pre-emergent weed preventer is for use on all grass types (with the exception of Dichondra or Bentgrass)
- COVERAGE: One 20.12 lb. bag of Scotts Halts Crabgrass & Grassy Weed Preventer covers 10,000 sq. ft.
- Roundup for Lawns Crabgrass Destroyer2 kills crabgrass and grassy weeds to the root
- This weed killer for lawns is formulated to kill even the toughest crabgrass and grassy weeds
- Apply this product to Kentucky bluegrass, fine fescue, perennial ryegrass and tall fescue
- Apply this product to actively growing weeds (during the early growth stages for the best results), when daytime temperatures are between 45°F and 90°F
- This 64 oz. container of Roundup for Lawns Crabgrass Destroyer2 is ready-to-use with a trigger sprayer
- KILLS WEEDS – NOT THE LAWN: When used as directed
- VISIBLE RESULTS IN 5 HOURS: Conquer unruly weeds and see visible results in as fast as 5 hours
- KILLS 470+ WEED TYPES AS LISTED: Kills broadleaf and grassy weeds including dandelion, chickweed and clover as well as crabgrass and yellow nutsedge – see product label for complete list of weed types
- KILLS THE ROOT: Kills weeds by contact down to the root
- READY-TO-USE FORMULA: No mixing required
The Ultimate Buying Guide: Conquering Crabgrass
Crabgrass can turn a beautiful lawn into an eyesore fast. Knowing how to choose the right killer is the first step to a green, healthy yard. This guide helps you pick the best product for your needs.
Key Features to Look For
When shopping for a lawn crabgrass killer, look closely at what the product promises to do.
- Pre-Emergent vs. Post-Emergent: This is the biggest choice. Pre-emergent products stop seeds from sprouting. You apply these in early spring before you see any grass. Post-emergent products kill the weeds you already see growing. Pick the right type for your timing.
- Lawn Safety: Check the label to make sure the killer works on your type of grass (like fescue, bluegrass, or St. Augustine). Some strong chemicals can hurt your good lawn.
- Speed of Action: Post-emergent killers should work quickly. You want to see results within a few days, not weeks.
- Longevity (For Pre-Emergents): A good pre-emergent should offer protection for several weeks or months to prevent repeat outbreaks.
Important Materials and Ingredients
The ingredients are what actually kill the weed. You must understand what you are spraying.
For **pre-emergents**, common active ingredients include Pendimethalin or Prodiamine. These stop the roots from forming when the seed tries to sprout. They are preventative medicine for your lawn.
For **post-emergents**, look for chemicals like Quinclorac or Sulfentrazone. These ingredients target the crabgrass cells directly, causing the weed to die off. Always check the concentration listed on the label; higher concentrations often mean stronger results, but also require careful application.
Factors That Improve or Reduce Quality
What makes one product better than another? It often comes down to formulation and timing.
Quality Improvers: Products mixed with surfactants often work better. Surfactants help the liquid stick to the waxy leaves of the crabgrass instead of rolling off. Also, liquid concentrates, when mixed exactly right, often provide more consistent coverage than granular products.
Quality Reducers: Using the wrong type of killer hurts quality. Applying a post-emergent killer when the crabgrass is very large and mature might lead to poor results. Also, using a product when rain is expected soon after application washes the chemical away, reducing its effectiveness. Always follow the drying time listed on the bottle.
User Experience and Use Cases
How easy is the product to use? This matters a lot for busy homeowners.
Granular Products: These are often easier for beginners. You spread them with a standard lawn spreader. They are great for large, flat areas. However, you must have a good spreader to avoid streaks of missed spots.
Liquid Sprays: These offer more precise control. You can spot-treat individual clumps of crabgrass easily. Backpack sprayers or hose-end sprayers are common tools for liquid application. They require more careful mixing but offer excellent coverage.
Best Use Case: If you know crabgrass pops up every year in May, use a pre-emergent in early April. If you missed the window and see small patches in July, switch immediately to a post-emergent spot treatment.
10 Frequently Asked Questions (FAQ) About Lawn Crabgrass Killer
Q: When is the best time to apply pre-emergent crabgrass killer?
A: Apply pre-emergent when soil temperatures consistently reach 55 degrees Fahrenheit for several days, usually early spring, before the crabgrass seeds germinate.
Q: Can I use crabgrass killer when my lawn is dormant (brown)?
A: Post-emergent killers will not work well on dormant crabgrass because the weed is not actively growing. Pre-emergents are applied before growth starts.
Q: Will crabgrass killer hurt my established desirable grass?
A: Most quality products are labeled safe for specific turf types (like Kentucky Bluegrass). Always read the label to ensure it won’t damage your existing grass.
Q: How long after applying do I need to wait to water my lawn?
A: This depends on the product. Granular products often need a light watering to activate the chemical barrier. Check the label, but usually, wait at least 24 hours before heavy watering after applying post-emergents.
Q: What happens if it rains heavily right after I spray a post-emergent killer?
A: Heavy rain can wash the chemical off the leaves before it absorbs, greatly reducing its effectiveness. You might need to reapply if the label suggests a waiting period before rain.
Q: Can I reseed my lawn after using a pre-emergent?
A: No. Pre-emergents stop all seeds from sprouting, including your new desirable grass seed. Wait at least 6 to 10 weeks after application before seeding, or use a product specifically labeled as “safe for new seed.”
Q: Is a liquid or granular product better for uneven lawns?
A: Liquid products are usually better for uneven or heavily shaded areas because you can aim the spray exactly where you need it, ensuring better coverage.
Q: How long will it take for the crabgrass to turn brown after spraying it?
A: Most effective post-emergent sprays start showing yellowing within 3 to 7 days. Complete death usually takes about two weeks.
Q: Do I need to remove the dead crabgrass after using a post-emergent?
A: Yes. Once the crabgrass is completely dead and brown, rake it out. This opens up the soil so your healthy lawn grass can fill in the bare spots.
Q: Are organic crabgrass killers effective?
A: Organic options, often based on corn gluten meal, primarily act as pre-emergents. They are generally less potent and require much earlier, more frequent application than synthetic chemicals.