Twenty Pound Bags of Natures Solution Worm Castings are available. These castings are 99.4% pure castings, not black which would indicate they had gone anaerobic somewhere in the processings. These are derived from a non-manure source and screen to 1/8 of an inch. These are approved for Organic Production, verified to USDA-NOP Organic Standards. For all outdoor trees, grass, flowers, shrubs, and vines. For hydroponics, nurseries, greenhouses and agriculture. For golf courses, homeowners, and landscapers. Use 1/8 inch of castings as a top dressing for new or existing plants, for transplanting, or planting new seeds. Use for indoor and outdoor container plant materials