Roundup Weed & Grass Killer4, 24 fl. oz. Take control of your outdoor space with Roundup® Weed & Grass Killer4. It kills tough weeds and grasses to the root, including dandelion, crabgrass, poison ivy, clover (red & white), spotted spurge, other broadleaf weeds. It is rainproof in as fast as 30 minutes, produces visible results in hours, and allows you to plant 1 to 30 days after application (see booklet for details).