This product contains two types of ingredients: some that help prevent weeds and others that kill existing weeds. When applied prior to its germination, Pennington Signature Series Crabgrass Preventer prevents crabgrass from growing and suppresses other weeds.
Additionally, this product controls crabgrass that has already germinated and emerged. Post-emergence control is limited to crabgrass only but is effective up to 4 weeks after crabgrass has germinated. Works Best On Established grass
How To Use Apply: This product should be applied only to lawns that are well-established and only during the spring or fall. This timing generally corresponds to the time when crabgrass first becomes visible. For newly established lawns, initial application of this product should be made only after grasses have developed a vigorous root system, uniform stand and received at least two mowings following seeding, sodding or sprigging. Exception: In newly established lawns of Kentucky bluegrass, perennial ryegrass and/or tall fescue, this product may be applied two weeks after the first sign of germination.