Wiggle Worm Soil Builder pure earthworm castings are surely Mother Nautre's best kept growing secret. Earthworm castings contain abundant essential elements plants need for healthy growth. Odorless and non-toxic, worm castings are a natural organic fertilizer that will not wash out with watering, and will not burn even delicate plants. Castings rival chemical fertilizers in their nutrient composition, providing a concentrated source of calcium, magnesium, and nitrogen. Castings are also safe - you can use them for annuals, perennials, seedlings, African violets, even cacti and succulents, without any threat of chemical harm to either your plants or yourself. Castings come in two sizes; 15 and 30 lb. Indoors, use one part castings to three parts potting soil. Outdoors, line the bottom of your hole or furrow with three inches of castings.