Naturally occurring Iron (FeHEDTA). People and pet safe. 5 in 1: Kills broadleaf weeds, disease, moss, algae, plus greens up lawns. Works fast (hours), in low temps, with no unpleasant odor. Reseed in only 1 day, and can apply to new grass after only 1 week. Active ingredient: 1.50% Iron HEDTA (FeHEDTA).