Use Spectracide Weed Stop for lawns plus crabgrass killer to kill over 470 types of weeds as listed, including crabgrass. The product produces visible results in 5 hr. This product kills broadleaf and troublesome grass weeds including dandelion, chickweed and clover as well as crabgrass, foxtail and yellow nutsedge. Apply when daytime temperatures are between 45 deg F and 90 deg F. Do not apply to Bermuda grass when daytime temperatures exceed 85 deg F.