Green Light Amaze Grass and Weed Preventer, 10 Pound Don't pull weeds - prevent them One application prevents weeds up to 4 months Forms a protective barrier in the soil surface, which prevents weeds from emerging Controls weeds, including Henbit, Prostate Knotweed, Shepherdpurse, Yellow Woodsorrel, Crabgrass, Foxtail, Common Chickweed and Common Purslane Use on listed established flowers, roses, trees and shrubs