Nope, you're in the clear! Roundup® for Lawns Crabgrass Destroyer (Model 4388501) is specifically formulated to kill crabgrass and other grassy weeds without harming your lawn—as long as it's used on the right grass types and according to the label directions2. It’s safe for common cool-season grasses like: - Kentucky bluegrass - Perennial ryegrass - Fine fescue - Tall fescue Just be sure to apply it when weeds are actively growing and temps are between 45°F and 90°F for best results