Preen Lawn Crabgrass Control prevents crabgrass and other grassy and broadleaf weeds for up to 4-months when applied prior to their germination in lawns and ornamental turfgrasses. It also provides post-emergence control of seedling crabgrass for up to 4-weeks after it germinates. Don't choose between killing and preventing get both. Because it can be applied later in spring, Preen Lawn Crabgrass Control provides season-long control for some of the toughest weeds, including crabgrass, chickweed, henbit, yellow foxtail and spurge. Use it on many types of cool and warm season grasses, including Bent grass, Fescues, Kentucky bluegrass, Ryegrass, Bermudagrass, Carpet grass, St. Augustine grass and Zoysiagrass.