Ortho GroundClear Weed & Grass Killer Ready-to-Use 1-gal. spray has been specifically formulated to kill all types of weeds that are green and growing like dandelions, ragweed, crabgrass, oxalis, moss, mustards, and more (as listed). Use on walkways, driveways, under trees, in landscape beds and around vegetable gardens (Apply directly to weeds). The fast-acting spray produces visible results in just 15 minutes and weeds will generally turn brown in hours! It will be rainproof in 2 hours after application (upon drying). Apply Ortho GroundClear Weed & Grass Killer on a warm, sunny day any time of the year when weeds are small and actively growing. Apply when the winds are calm. For best results, re-apply every 2 to 3 weeks while difficult to control weeds, such as perennial or more established weeds, may require several applications for complete control. Ortho GroundClear Weed & Grass Killer is OMRI listed. For organic gardening.