Growing Green Earthworm Castings is an all-purpose natural fertilizer that comes to you straight from nature with no alterations whatsoever. Worm castings are a soil conditioner that is of unsurpassed fertility. Because it has an abundance of readily available non-burning nutrients, only a little needs to be used in your plant holes or seed furrows. At any concentration, even the most delicate seed or bedding plant is safe. This means no fear of overuse or misuse.