Ortho GroundClear 32 oz. Concentrate Weed & Grass Killer. This quick and effective solution begins working immediately, delivering visible results in just 15 minutes. Ideal for patios, pavers, and landscapes, it kills all types of weeds and grasses, including crabgrass, dandelions, and chickweed. Safe for use in organic gardening, this rainproof formula ensures long-lasting protection. Active ingredient: Ammonium Nonanoate.