Crabgrass (Digitaria spp.) is a fast-spreading annual weed that's found throughout North America. The grass appears in the early summer and can quickly overwhelm a flower bed or a poorly kept lawn before dying off during the cooler fall season. Gardeners can use a fusion of manual removal and chemical treatments to keep crabgrass at bay and protect the beauty and health of their backyard or lawn.
Trim your lawn with a lawn mower if you are trying to kill crabgrass that's growing among your turfgrass. Regular mowing keeps the crabgrass from developing seeds and spreading and, combined with chemical control methods, will help to successfully eradicate the weed.
Dig out the crabgrass manually with a handheld spade. This is ideal for isolated bunches of crabgrass. Slide the spade under the center of the crabgrass bunch to uproot it.
Treat the ground with a chemical control if manual removal is not feasible. Spray the area with a pre-emergent herbicide like pendimethalin or benefin. This kills the crabgrass seeds and keeps them from germinating. Apply such herbicides in the early spring.
Follow the pre-emergent herbicide with a post-emergent herbicide like clethodim or fluazifop. Such chemicals are selective and will kill crabgrass without damaging the turfgrass. If you're trying to remove crabgrass that's not growing in turfgrass, any standard non-selective herbicide, such as glyphosate, will work effectively against the weed.