Does your beautiful green lawn suddenly sprout those annoying, spiky patches of crabgrass? It’s a common summer headache for homeowners everywhere. You spend time and money making your grass look perfect, only to have this invasive weed take over. Choosing the right crabgrass killer can feel like a confusing maze. Do you need a pre-emergent or a post-emergent product? Will it harm your good grass? These questions stop many people from tackling the problem effectively.
Don’t let stubborn crabgrass win the battle for your yard this season. This guide cuts through the confusion. We will break down exactly what you need to know to identify the best crabgrass killer for your specific situation. You will learn the key differences between products, understand application timing, and discover how to achieve that lush, weed-free look you desire.
Ready to reclaim your lawn? Keep reading as we dive into the best strategies and products to finally defeat crabgrass for good.
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.
- 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
- 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
- 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
- Scotts Halts Crabgrass & Grassy Weed Preventer prevents the germination of listed lawn weeds so you can enjoy your lawn
- 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
- Apply this pre-emergent weed 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 product
- This lawn care product is for use on all grass types (with the exception of Dichondra or Bentgrass)
- One 20.12 lb. bag of Scotts Halts Crabgrass & Grassy Weed Preventer covers 10,000 sq. ft.
Your Guide to Winning the War Against Crabgrass
Crabgrass can quickly turn a beautiful lawn into an eyesore. To keep your grass green and healthy, you need the right killer. This guide helps you choose the best product for your needs.
Key Features to Look For
When shopping for a crabgrass killer, look for these important features:
- **Pre-emergent vs. Post-emergent:** Decide when you want to stop the grass. Pre-emergent products create a barrier *before* crabgrass seeds sprout. Post-emergent products kill grass that has *already grown*.
- **Selective vs. Non-Selective:** A selective killer targets only the crabgrass. It leaves your desired lawn grasses unharmed. A non-selective killer kills *everything* it touches, including your good grass. Choose selective for spot treating your lawn.
- **Speed of Action:** Some products work within hours, while others take several days. Fast-acting products offer quicker results.
- **Longevity (for Pre-emergents):** How long does the barrier last? A longer-lasting product means fewer applications throughout the season.
Important Materials and Ingredients
The ingredients determine how the killer works. Read the label carefully.
For pre-emergent control, common active ingredients include **Prodiamine** or **Dithiopyr**. These chemicals stop the tiny seeds from developing roots.
For post-emergent control, look for chemicals like **Quinclorac**. This ingredient targets the crabgrass cells and stops their growth. Sometimes, these products include a surfactant, which helps the chemical stick to the weed better.
Factors That Improve or Reduce Product Quality
The quality of your chosen killer depends on several factors.
Factors that improve quality:
- **Correct Timing:** Applying a pre-emergent too early or too late severely reduces its effectiveness. You must apply it before soil temperatures reach the germination point (usually when soil hits 55°F for several days).
- **Proper Application Rate:** Follow the directions exactly. Using too little won’t kill the weed. Using too much wastes money and might harm your lawn.
- **Weather Conditions:** Post-emergent killers work best when applied before a sunny, warm day but *before* heavy rain. Rain washes the product away too quickly.
Factors that reduce quality:
- **Applying to Stressed Grass:** Do not apply harsh chemicals when your lawn is already dry or suffering from heat stress. This increases the chance of burning your good grass.
- **Ignoring Soil Moisture:** Pre-emergents often need light watering after application to activate the chemical barrier in the soil. Not watering reduces their power.
User Experience and Common Use Cases
People use crabgrass killers in different ways based on their lawn situation.
Use Case 1: Prevention (Pre-emergent)
Most homeowners choose this route. You apply the product early in spring, usually around the time tulips bloom. This creates a protective shield. User experience here is usually low maintenance—you apply it once or twice, and then you wait. If the application is timed right, you rarely see any crabgrass later.
Use Case 2: Eradication (Post-emergent)
If you missed the pre-emergent window, you need a post-emergent. Users often mix this in a small sprayer and spot-treat clumps of crabgrass. Be careful! Users report that overspray easily damages desirable turf. Success depends on treating the crabgrass when it is small and actively growing.
Use Case 3: Granular vs. Liquid
Granular products are easy to spread evenly with a spreader. Liquid products often penetrate the soil or weed faster. Liquid application requires careful mixing and spraying for even coverage. Granular application is often preferred by beginners for its simplicity.
10 Frequently Asked Questions About Lawn Crabgrass Killers
Q: When is the best time to apply a pre-emergent crabgrass killer?
A: Apply it in early spring before soil temperatures consistently reach 55 degrees Fahrenheit. This stops the seeds from sprouting.
Q: Can I use a post-emergent killer if I already put down a pre-emergent?
A: Yes, you can. The post-emergent kills the weeds that managed to grow through the barrier. Always check the labels to ensure the products won’t interact negatively.
Q: Will crabgrass killer harm my dog or pets?
A: Most products require pets to stay off the lawn until the product has completely dried. Read the specific re-entry instructions on the label.
Q: What happens if it rains right after I apply a post-emergent?
A: Heavy rain washes the chemical away. This reduces its effectiveness, and you may need to reapply it after the weather clears.
Q: Why are some crabgrass killers more expensive than others?
A: More expensive products often use newer, more effective active ingredients, or they offer a longer period of control in a single application.
Q: Can I overseed my lawn right after using a pre-emergent?
A: No. Pre-emergents stop all seeds from growing, including the seeds of your good grass. Wait several weeks or months, depending on the product instructions, before seeding.
Q: What is the difference between a selective and non-selective killer?
A: A selective killer only targets the weed. A non-selective killer kills all plant life it touches, including your lawn.
Q: How long does it take for a post-emergent to kill the crabgrass?
A: Many modern post-emergents start showing results in just a few days, but full death might take one to two weeks.
Q: Do I need to water after applying a granular pre-emergent?
A: Yes, usually. Most granular products require about a quarter inch of water to move the chemical barrier down into the top layer of the soil.
Q: What should I do if the crabgrass is already very large?
A: Large crabgrass is tough to kill with chemicals alone. You will likely need to use a spot treatment with a strong post-emergent, or physically pull the large clumps out.