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 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.
- Mesotrione, a potent herbicide, immediately absorbs and starts working upon application, yet it may take 2-3 weeks for full weed death. Activation requires water; if no rainfall occurs within 10 days, apply 0.15 inches of water.
- Targeting 46 broadleaf species and grasses, including Barnyard grass, Carpetweed, Chickweed, Clover, Crabgrass, and Dandelion, Mesotrione is versatile.
- Suitable for Kentucky Bluegrass, Centipede grass, Buffalo grass, Tall Fescue, Perennial Ryegrass, Fine Fescue, and St. Augustine Grass (sod only). Avoid Bentgrass, Poa annua, kikuyugrass, zoysiagrass, seashore paspalum, and bermudagrass. Apply Mesotrione on dormant bermudagrass to eliminate weeds.
- Mesotrione inhibits photosynthesis in susceptible plants, distributing throughout the plant via roots and leaves. It's an effective herbicide preventing crabgrass seed germination and eliminating broadleaf weeds on contact, encouraging the growth of certain cool-season turfgrass in a weed-free environment.
- 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
- STOP WEEDS BEFORE THEY START: This pre-emergent and post-emergent herbicide targets weed seeds just as they're germinating; Say goodbye to troublesome weeds like crabgrass and creeping charlie before they take over your lawn or garden
- COST-EFFECTIVE: With low usage rates, our product provides an economical weed-killing solution, ideal for both small and large areas
- BROAD-SPECTRUM USAGE: Not just for residential lawns; This formula is perfect for public golf courses, roadside areas, and even pre-planting crop spaces, offering versatile weed control
- EASY APPLICATION: Our "Tip and Pour" bottles make it simple to apply the weed killer, ensuring a hassle-free experience
- CONVENIENT SIZE OPTIONS: We've got you covered whether you're treating a small patch or a large area; Pick from 8 ounces, 64 ounces, or 320 ounces to best suit your needs; PLEASE NOTE: 3-pack of disposable is included with purchase and weed sprayer is sold separately
- 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
- TRUSTED PERFORMER: Torocity contains 40.0% mesotrione; the same active ingredient as the leading brand, Tenacity. For more than 20 years, mesotrione has been the trusted choice for effective weed control in newly seeded areas as well as established turf.
- FLEXIBLE APPLICATION TIMING: This double-hitter herbicide allows timing forgiveness with both pre- and post-emerge activity. Compared to pre-emerge only herbicides, Torocity widens the application window so you can stop new weeds before they start and take down the weeds you already have.
- BROAD-SPECTRUM WEED CONTROL: Torocity delivers powerful control of many broadleaf and grassy weeds, including crabgrass, ground ivy, clover, oxalis, and dandelion.
- IDEAL TURF RENOVATION PARTNER: Torocity is one of the few herbicides labeled for just-seeded Kentucky bluegrass, tall fescue, perennial ryegrass, and centipedegrass. Apply before seed germination to prevent weed competition and encourage new grass growth. Torocity may be used on new seedings, grass grown for sod, and established turf. Do NOT apply to Bentgrass, Zoysiagrass, and actively growing Bermudagrass. See label for complete list of tolerant turfgrass species.
- EASY-MEASURE TOOL INLCUDED: We took out the guesswork so you get the right rate – easily. Our pre-marked syringe highlights the exact amount of product needed per gallon of water. Torocity is activated by water, if rainfall doesn’t occur within 10 days of application, water the area with 0.15 inches of water.
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.