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
- 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
- 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…
- Kills even the toughest weeds, like dandelion and clover
- Specially formulated to control more than 200 weed types
- Starts working on contact
- Kills the root so weeds don’t come back
- Granular weed control that kills tough lawn weeds, not the lawn
- 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
- 3-IN-1 FORMULA: Scotts Turf Builder Triple Action1 is a three-in-one lawn fertilizer and weed control formula that kills listed lawn weeds, prevents crabgrass, and feeds grass to build thick, green lawns
- WHERE TO USE: This grass fertilizer, crabgrass preventer, and clover and dandelion killer for lawns is for use on Bahiagrass, Centipedegrass, Kentucky Bluegrass, Perennial Ryegrass, Bermudagrass, Tall Fescue, Fine Fescue, and Zoysiagrass
- LAWN WEED CONTROL: This lawn care product is a weed killer for lawns that controls dandelion, clover, dollarweed, ground ivy, chickweed, plantain, henbit, English daisy, and other listed lawn weeds
- CRABGRASS PREVENTER: This pre-emergent weed killer also prevents crabgrass for 4 months (will not kill existing crabgrass); stops other listed grassy weeds from invading your lawn
- HOW TO USE: Apply to a wet lawn with a Scotts spreader, then water in after 24 hours; apply in early spring when dandelions are actively growing
- LAWN FRIENDLY FORMULA: Our lawn friendly weed killer spray formula contains three proven ingredients that specifically target common lawn weeds, so it won't harm your grass (when used as directed)
- EASY APPLICATION: The continuous spray Comfort Wand weed killer sprayer applicator makes it easy to apply for lawn care, allowing for precise spray control and maximum accuracy without any pumping required
- LAWN WEED CONTROL: Use Ortho WeedClear Weed Killer for Lawns with Comfort Wand, a lawn weed killer, to kill weeds down to the root without harming your grass (when used as directed), with visible results in hours
- KILLS OVER 250 WEEDS: This broadleaf weed killer for lawns targets over 250 common broadleaf lawn weeds, including dandelions, clover, poison ivy, chickweed, and dollarweed (see product label for complete weed list)
- FAST VISIBLE RESULTS: See visible results in hours; this lawn care formula that is rainproof in 1 hour after drying, and people and pets may re-enter the treated area after the spray has dried
- One application prevents crabgrass all season long
- Apply in spring to prevent crabgrass and problem weeds all season long
- Fall application prevents winter weeds, such as poa annua, henbit and chickweed
- Rain, snow or freezing weather after application won't affect product performance
- Apply in fall to prevent moss
- Professional-grade, four-way weed and feed. Feeds to build thicker, greener lawns.
- Eliminates over 250 common weeds including dandelions, clover, chickweed, plantain and more.
- Provides superior performance throughout entire growing season, even when applied in the cooler temperatures of spring and fall
- Small particles for more coverage per square inch and superior performance.
- Not for use on Floratam St. Augustine grass, dichondra, carpetgrass, creeping bentgrass, or turf containing desirable clovers. Not sold in NH or WA.
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.