Does your beautiful green lawn suddenly look like a patchwork quilt of dandelions and clover? You spend hours mowing, watering, and nurturing your grass, only to have stubborn weeds pop up and steal the show. It’s frustrating! Pre-emergent herbicides are great for stopping seeds before they sprout, but what happens when those unwelcome visitors have already pushed through the soil?
That’s where post-emergent weed killers come in. Choosing the right one, however, can feel like navigating a maze. Should you use a selective spray that targets broadleaf invaders but spares your grass? Or do you need a non-selective killer for tough patches? Getting this wrong can damage your turf or simply fail to eliminate the problem.
This guide cuts through the confusion. We will break down exactly what post-emergent weed killers are, when to use them, and how to pick the perfect product for your specific weed woes. By the end, you will have the knowledge to reclaim your lawn’s perfect green look with confidence. Let’s dive into conquering those established weeds!
Top Post Emergent Weed Killer For Lawns Recommendations
- Low, economical use rate of 1 to 4 pints per acre
- Controls many broadleaf weeds & woody plants
- Use in turf, pastures, rangeland, ditch banks, fences…
- WEED KILLER SPRAY FOR LAWNS: With a simple hose-end application, kill weeds in your lawn, including dandelions, chickweed, clover, crabgrass and foxtail with Ortho WeedClear Lawn Weed Killer Ready-to-Spray
- FAST-ACTING WEED CONTROL: This weed killer hose sprayer kills listed weeds like crabgrass, dandelion, clover, chickweed and creeping charlie down to the root and gets results with 1 application
- COVERAGE: This 32 fl. oz. container of Ortho WeedClear Lawn Weed Killer Ready-to-Spray provides up to 5,000 sq. ft. of lawn care
- HOW TO USE: Apply to listed lawn weeds that are young and actively growing by connecting your garden hose to the weed killer sprayer, sliding the switch to "ON" and spraying evenly until the lawn is wet
- WHERE TO USE: This spray weed killer for lawns won't harm lawn grasses when used as directed - use on lawn grasses including Bermudagrass, Buffalograss, Fescues, Kentucky Bluegrass, Ryegrass and Zoysiagrass
- WHERE NOT TO USE: This weed and dandelion killer for lawns and lawn care product should not be used on Dichondra, Carpetgrass, 'Floratam' St. Augustinegrass, Creeping Bentgrass, or turfgrass where desirable clovers are present
- LAWN WEED KILLER: Scotts Weed Control for Lawns is a weed killer for grass that starts working on contact to kill even the toughest weeds down to the root
- KILLS LISTED WEEDS: This broadleaf weed killer for lawns controls over 200 listed weeds, including dandelion, clover, dollarweed, chickweed, poison ivy, henbit, oxalis, ground ivy, and purslane
- WHEN TO USE: Apply weed killer granules in the spring or early fall when broadleaf weeds are actively growing
- COVERAGE: One 14 lb. bag of Scotts Weed Control for Lawns granular weed killer covers 5,000 sq. ft.
- KILL WEEDS NOT YOUR LAWN: Use Ortho WeedClear Weed Killer for Lawns Ready-To-Spray weed killer sprayer to kill weeds down to the root, without harming your lawn (when used as directed); you'll see visible results in hours
- HOW TO USE: To apply this herbicide weed killer, connect your garden hose to the sprayer, slide the switch to 'ON' to begin spraying; visible results in hours; rainproof in 1 hour upon drying; people and pets may enter the treated area after dried
- LAWN FRIENDLY: This weed spray contains three proven ingredients that target common lawn weeds, so it won't harm your grass (when used as directed)
- LAWN WEED KILLER: This broadleaf weed killer for lawns kills over 250 common broadleaf weeds, including dandelions, clover, poison ivy, chickweed, and dollarweed (see product label for complete weed list)
- COVERAGE: One 32 fl. oz. container of Ortho WeedClear Weed Killer for Lawns Ready-to-Spray provides lawn care for up to 16,000 sq. ft. for Southern lawns or 8,000 sq. ft. for Northern lawns
- ✔️EASY MIX PACKET NO measuring required!
- ✔️PROFESSIONAL GOLF COURSE QUALITY
- ✔️FAST ACTING
- ✔️KILLS DANDELIONS 120 MORE
- ✔️SAFE ON ST. AUGUSTINE+ ALOT MORE
Your Guide to Winning the War Against Weeds: Choosing Post-Emergent Weed Killer
Weeds can quickly turn a beautiful green lawn into a patchy mess. Post-emergent weed killers attack weeds after they have already sprouted. This guide helps you select the best product to keep your grass looking fantastic.
Key Features to Look For
When shopping, look closely at the product label. Certain features make one weed killer better than another for your specific needs.
Targeted Weed Control
- Broadleaf vs. Grassy Weeds: Most common lawn weeds are broadleaf (like dandelions or clover). Some products only kill broadleaf weeds, while others handle grassy weeds too. Choose a product matching the weeds you see most often.
- Selective vs. Non-Selective: Selective killers target only the weeds, leaving your desirable grass unharmed. Non-selective killers destroy all plants they touch, including your lawn. Always choose a selective killer for established lawns.
Speed and Duration of Action
- Fast-Acting Formula: Some products show results within hours. Faster action means quicker visual improvement.
- Residual Activity: Some formulas keep working in the soil for a short time, preventing new weeds from sprouting after the initial spray.
Important Ingredients and Materials
The active ingredients determine how the weed killer works. You need to understand these chemicals to ensure safety and effectiveness.
Common Active Ingredients
- 2,4-D, MCPP, and Dicamba: These are common ingredients that effectively control many broadleaf weeds. They work by mimicking plant growth hormones, causing the weeds to grow uncontrollably until they die.
- Quinclorac: This ingredient often targets specific grassy weeds, like crabgrass.
Formulation Types
- Liquid Concentrates: You mix these with water before spraying. They offer good coverage and are often more cost-effective for large yards.
- Ready-to-Use (RTU): These come pre-mixed in a sprayer bottle. They are convenient for small areas or quick spot treatments but cost more per ounce.
Factors Affecting Product Quality
Several factors influence how well a weed killer performs. Consider these points before you buy.
What Improves Quality?
- Temperature Suitability: Most broadleaf killers work best when temperatures are between 60°F and 85°F. Applying during ideal weather boosts effectiveness significantly.
- Surfactants: Some formulas include surfactants, which help the spray stick to the waxy surface of the weed leaves, improving absorption.
What Reduces Quality?
- Rain: Heavy rain soon after application washes the chemical off the weeds. Check the label for “rainfast” time—how long it needs to stay dry.
- Drought Stress: Weeds growing under severe drought conditions are tougher to kill. Healthy, actively growing weeds absorb chemicals better.
User Experience and Use Cases
Think about how you plan to use the product. A simple application process leads to a better experience.
Application Methods
- Spot Treating: Use an RTU sprayer or a small handheld pump sprayer for isolated weeds. This saves product and minimizes exposure to healthy grass.
- Broadcast Spraying: Use a larger tank sprayer or a hose-end sprayer to cover an entire lawn area. This is faster if you have many weeds spread out.
Lawn Safety
Always confirm the product is safe for your specific type of grass (e.g., Bermuda, Fescue, or Zoysia). Applying a product safe for St. Augustine grass onto a Kentucky Bluegrass lawn might cause severe damage.
Top 10 Frequently Asked Questions (FAQ)
Q: When is the best time of year to apply post-emergent killer?
A: Spring and early fall are usually the best times. Weeds are actively growing then, making them easier to kill. Avoid applying during extreme heat.
Q: How soon after spraying can my dog go back on the lawn?
A: This varies by product. Generally, let the treated area dry completely, which often takes a few hours. Always read the label for specific safety waiting periods.
Q: Will this kill clover in my lawn?
A: Many post-emergent herbicides are specifically designed to target clover. Check the label to ensure clover is listed as a target weed.
Q: Can I mow my lawn right after spraying?
A: No. Wait at least two days after application before mowing. Mowing too soon removes the leaves the chemical needs to absorb.
Q: What if the weeds look yellow but aren’t totally dead after a week?
A: Some tough weeds take longer to die. If you see yellowing, the product is working. Wait about two weeks total. If no change occurs, you might need a second, lighter application.
Q: Do I need to water the lawn after applying?
A: It depends on the product. If the label says it needs rain or water to activate the residual effect, then yes. Otherwise, wait until the surface is dry.
Q: What is the difference between pre-emergent and post-emergent?
A: Pre-emergent stops seeds from sprouting. Post-emergent kills weeds that have already popped up out of the soil.
Q: Can I mix weed killer with fertilizer?
A: Some products are sold as a “Weed and Feed” combination. If your products are separate, check the label carefully. Mixing chemicals that are not meant to be combined can hurt your lawn.
Q: How long until I see results?
A: Results vary, but you should start seeing wilting or yellowing within 24 to 72 hours for fast-acting formulas.
Q: Should I use this near my vegetable garden?
A: Be extremely careful. Spray drift can harm non-target plants. Use a shield or choose a product with low volatility (less likely to become airborne vapor) if spraying near sensitive plants.