BioAdvanced Season Long Weed Control kills existing lawn weeds and prevents new ones from emerging for up to 6 months. Contains a post-emergent and a pre-emergent. Won't harm lawns. Apply any time, spring through fall when temperatures range from 50-90 degrees farenheit. Rainproof in one hour. Treats up to 3750 sq ft for Northern Turf and up to 7500 sq ft for Southern Turf.