Spectracide Weed Stop for Lawns Plus Crabgrass Killer Concentrate, 32 ounces controls more than 470 types of weeds as listed – and it won’t harm your lawn when used as directed. This ready-to-spray formula kills by contact, down to the root, with visible results in as little as 5 hours. It controls all types of listed broadleaf and grassy weeds, including crabgrass, dandelion and more(see product label for complete list). This product is rain fast in as little as 3 hours, so it won’t wash off. The Quick Flip hose-end sprayer activates at the flip of a switch. Apply Spectracide Weed Stop For Lawns Plus Crabgrass Killer Concentrate when temperatures are between 45 and 90 degrees. Spray until wet to control weeds. Do not apply when daytime temperatures are above 90 degrees as lawn injury can occur. Read the entire label before using.