Earth Science 4 Lb. Earthworm Castings. They Are The Richest, Most Natural Compost Available. Naturally Non-Burning And Odorless, Worm Castings Add Essential Organic Matter That Increases Microbial Activity For A Living, Nutrient Rich Soil. Use For Seed Starting, Indoor And Outdoor Plants And Gardens Including Container Gardens. For Trees And Shrubs, Simply Sprinkle A Small Amount In. Soil Around Base Of Plant. Slowly Enriches Soil With More Nutrients Than Most Yard Compost Without Burning Plants. All Organic.