Post-Emergent Herbicides: The Do’s and Don’ts for Effective Weed Control
Post-emergent herbicides, like Weed and Feed 24-0-16 and Surge® Weed & Feed 16-0-9, are essential tools for tackling weeds that have already sprouted and are actively growing. Unlike pre-emergent herbicides, which prevent weeds from germinating, post-emergents target weeds that have emerged above the soil surface. However, to use them effectively and safely, there are key guidelines to follow. Let's outline the do’s and don’ts of post-emergent herbicide use, ensuring you get the best results without harming your lawn.
The Do's of Post-Emergent Herbicides
-
Identify the Weeds Correctly: Before applying a post-emergent herbicide, make sure you’ve correctly identified the weeds you're trying to eliminate. Different herbicides target different types of weeds. Some are selective, meaning they kill only certain types of weeds (e.g., broadleaf or grassy weeds), while others are non-selective and can kill any plant they come into contact with. Correct identification helps you choose the right product and prevents unnecessary damage to desirable plants.
-
Follow Manufacturer Instructions: Always read and follow the instructions on the herbicide label carefully. Manufacturers provide valuable guidance on the correct application rates, timing, and safety precautions. For example, weed and feeds typically need to be applied to wet grass and not watered-in for at least 24 hours. Misusing a product can either lead to ineffective weed control or damage to your lawn.
-
Apply During Ideal Weather Conditions: The weather plays a crucial role in the effectiveness of post-emergent herbicides. Ideally, apply herbicides on a dry, calm day with temperatures between 60°F and 85°F. This ensures that the herbicide sticks to the weeds and is absorbed effectively. Avoid applying during windy days, as this can lead to herbicide drift, where the chemicals land on unintended plants.
-
Apply When Weeds Are Actively Growing: Post-emergent herbicides are most effective when the weeds are actively growing. Typically, this means applying the herbicide during the early to mid-growth stages of the weeds, when they are young and still vulnerable. Weeds that are stressed (due to drought, frost, or other factors) may not absorb the herbicide as efficiently.
-
Wear Protective Gear: Protect yourself when handling and applying herbicides. Wear gloves, long sleeves, pants, and safety glasses. Always read the safety instructions on the label for further guidance. If using a sprayer, wear a mask to avoid inhaling fumes, especially with stronger herbicides.
-
Use the Right Equipment: Choose the proper application equipment for your needs. For small areas, handheld spreaders work well for granular post-emergents and sprayer bottles work well for liquids. For larger lawns, consider a tank sprayer liquids or a broadcast spreader for granular. Ensure that the equipment is clean and in good working condition before use.
-
Know When to Water: Typically, watering is done either immediately after applying or 24 hours later, depending on the product. Be sure to follow the instructions to know whether irrigation is needed and when to water.
The Don'ts of Post-Emergent Herbicides
-
Don’t Apply on Windy Days: Wind can carry herbicide particles to unintended areas, affecting other plants and potentially harming your garden or lawn. For the best results and safety, apply post-emergent herbicides on calm, windless days. If the wind is blowing, it’s better to wait for a more favorable day.
-
Don’t Apply Before Rain: Most herbicide labels recommend waiting 24 to 48 hours after application before expecting rain. Avoid applying if rain is forecast within this period. Rain can wash away the herbicide, reducing its effectiveness. If it does rain soon after application, you may need to reapply.
-
Don’t Apply to Dormant Lawns or Plants: Avoid using post-emergent herbicides on lawns or plants that are not actively growing. Herbicides are designed to target actively growing weeds, and applying them to dormant plants can cause unnecessary stress or damage to your lawn or garden. It’s best to apply during the growing season when the grass and plants are healthy.
-
Don’t Mix Herbicides Without Understanding the Combination: Mixing different chemicals can lead to toxic reactions or diminished effectiveness. If you plan to combine post-emergent herbicides with other treatments (such as fungicides or insecticides), make sure to check the label for compatibility. When in doubt, test the mixture on a small area before applying it to your entire lawn or garden. Click here to read about applying products at the same time.
-
Don’t Over-Apply: Applying too much herbicide can damage your lawn, garden, and surrounding plants. It may also harm beneficial insects and pollinators. Follow the recommended dosage to avoid over-application. More isn’t always better when it comes to weed control.
-
Don’t Use on Dry Grass: Granular post-emergent herbicides are most effective when applied to wet grass. Wet conditions help the herbicide to adhere properly to the leaves of the weeds and be effective.
-
Don’t Forget to Clean Your Equipment: After using post-emergent herbicides, clean your sprayer or applicator thoroughly. Herbicide residue can linger and cause damage to plants when used again. Rinse your equipment with water and, if necessary, a mild detergent to prevent cross-contamination.
Conclusion
Post-emergent herbicides are a valuable tool for controlling weeds that have already emerged and are actively growing. However, to use them effectively and safely, it’s crucial to follow the do’s and don’ts outlined above. By identifying the weeds correctly, applying at the right time and weather conditions, and using the correct equipment, you can ensure that your lawn and garden stay healthy and weed-free without causing unnecessary harm to your plants or the environment. With a little care and attention to detail, post-emergent herbicides can be an effective and efficient way to manage your outdoor spaces.
