Preen Garden Weed Preventer 13 lb. Bag covers 2,080 sq. ft. It prevents weeds before they start for up to 3 months and is guaranteed to be safe for use around over 200 established flowers, vegetables, trees, and shrubs. Apply anytime in spring, summer, or fall in flower, shrub, and all bedding areas. It is not for use on lawns and does not kill existing weeds. It is safe for use on edibles.