Roundup For Lawns2 is a tough weed killer for use on northern grasses that kills weeds, not the lawn. This tough weed killer kills 253 types of weeds and works fast on hard-to-kill weeds. It won't harm lawns when used as directed on northern grasses, including bluegrass, fescue, zoysia, perennial ryegrass. The fast acting, lawn friendly 32 oz concentrate formula covers up to 5000 sq-ft. This product starts working immediately, is rain-proof in as little as 3 hr and controls weeds for up to 3 months. Roundup For Lawns2 kills the root so weeds won't come back. Apply Roundup For Lawns2 to actively growing weeds during the early growth stages for the excellent results. Apply in the spring or fall when daytime temperatures are between 45 deg F and 90 deg F. Roundup For Lawns2 is a simple step for home lawn care. No weeds. No worry.