How to Kill Crabgrass

A few isolated clumps can be pulled by hand after rain when soil is soft. Grab the center of the clump and pull slowly to get the root crown. For scattered patches across the lawn, spot spraying with a post-emergent herbicide is more practical. For widespread infestation covering 30% or more of the lawn, consider a full renovation approach in fall rather than chasing individual plants all summer.

Quinclorac (sold as Drive XLR8 or in combination products) is the most effective selective post-emergent for crabgrass in cool-season lawns. It kills crabgrass without harming bluegrass, fescue, or perennial ryegrass. Always check the label for your specific turf type. Add a surfactant (sticker) to improve leaf adhesion.

Treat when crabgrass has 1 to 4 tillers (individual shoots from the central clump). At this stage, the plants are actively growing and absorb herbicide effectively. Mature crabgrass with seed heads is much harder to kill and will drop seeds before it dies anyway. Spray in the morning after dew has dried. Do not mow for 24 hours before or after application.

One application rarely kills all crabgrass. Plan for a follow-up treatment 10 to 14 days after the first. Check the label for the maximum number of applications per season. Treated crabgrass yellows and wilts within 7 to 10 days. Any plants still green after two weeks need a second spray.

Dead crabgrass leaves bare patches. If you don't fill those gaps with desirable grass, new crabgrass seeds will fill them next spring. Overseed in early September (Central Plains) when soil is still warm but crabgrass season is ending. Apply pre-emergent the following spring to break the cycle.