For best results, we recommend using Roundup® Weed & Grass Killer products on dry, warm, wind-free days. But if it’s about to rain, fear not — all of our products should dry and become rainfast within 30 minutes to 3 hours — some even faster.The products below have a rainfast range of 10 minutes to 3 hours. Scroll down to a product to see the rainproof time.
Weeds and Rain
Weeds love to sprout after it rains, which is why waiting for dry conditions is ideal. Waiting for rain-free days also ensures that Mother Nature won't wash away any of the product before it goes to work on the weed.