Spectracide Weed Stop For Lawns Plus Crabgrass Preventer Granules, 10.8-Pound, 2-Pack WONT HARM LAWNS: Wont harm lawns when used as directed  kills more than 200 types of weeds as listed. PRE-EMERGENT CRABGRASS KILLER: Prevents crabgrass and other undesirable annual grasses. UP TO 5 MONTHS CONTROL: Apply with a spreader at the rates directed on the product label. APPLY SPRING THROUGH FALL: Apply when weeds are actively growing. COVERAGE: This 10.8 pound bag covers up to 3,000 square feet of lawn.