The Roundup 64 oz. 50% Super Concentrate Weed and Grass Killer kills the roots of weeds and unwanted grass. The 64 oz. container of concentrate provides up to 42 Gal. of solution and can treat up to 12,750 sq. ft. of coverage. It is rainproof in 30 minutes, the solution won't wash away and you will see visible results in two to four days.