Roundup 365 Vegetation Killer, Weed & Grass Killer Plus 12 Month Preventer provides one-step weed protection for up to 12 months. This weed control kills and prevents many types of tough weeds and grasses for up to 12 months, including clover, dandelion, large and smooth crabgrass, poison ivy, and other broadleaf weeds, grassy weeds and brush. It is rainproof in as fast as 30 minutes and produces visible results in hours.