Many successful lawn-care professionals have discovered that the best way to kill crabgrass is to frequently survey the lawn and use a post-emergent herbicide once crabgrass appears. The younger a weed is, the easier it will be to kill. When you use a post-emergent herbicide on a young weed, the plant will not have the opportunity to produce seeds for the following season.
Many professional landscapers have found that their grass remains healthier when they use a post-emergent herbicide to kill crabgrass as opposed to a pre-emergent weed killer. Some pre-emergent herbicides can actually make a lawn weaker, because they hinder the development of not only weeds, but grass as well. The risk of this occurring is greater when the grass roots are not completely established in the soil.
Moreover, it’s often much cheaper to use a post-emergent herbicide. One reason for this is that pre-emergent crabgrass killers must be applied to an entire lawn. If the ground freezes after you apply the pre-emergent herbicide, you have to purchase additional weed killer and again run the risk of a frost rendering the treatment useless. With a safe post-emergent, you can kill crabgrass once it appears. A post-emergent weed killer only needs to be used in select areas.
Here at Crabgrass Alert, we suggest Agralawn Crabgrass Killer, a post-emergent weed killer that’s safe for St. Augustine, Common Bermuda, Bahia, and Centipede lawns. This inexpensive herbicide will kill crabgrass within three to five days of application. When used properly, Agralawn Crabgrass Killer will fend off several species of weeds.