Roundup Dual Action Weed & Grass Killer with Trigger Sprayer, 1 gal. features a powerful dual action formula designed to kill existing weeds and grasses down to the root. It also prevents new weeds from growing for up to four months by creating an invisible barrier in the soil. This product is i for use on driveways, sidewalks, patios, around trees, landscaping areas, along fences, and gravel areas. For optimal results, apply during warm, sunny weather when temperatures are above 60 degrees Fahrenheit. It becomes rainproof in just 30 minutes and delivers visible results within 6 hours.