Earthworm castings are a natural by-product of the worm business.
It is estimated that one commercial growing bed 3' X 8' will produce 800 pounds of pure casting yearly. Earthworm castings are the best imaginable potting soil for greenhouses, or house plants, as well as gardening and farming. It will not burn even the most delicate plants. All nutrients are water-soluble, making it an immediate plant food. Earthworm castings can also be used as a planting soil for trees, vegetables, shrubs and flowers.