Gaia Green - Worm Castings 2L U.S. (NA02) Pouch. Gaia Green Worm Castings are the unprocessed manure of earthworms. This all-purpose soil amendment is high in organic matter, and adds essential minerals to the soil to encourage strong growth of microorganisms. Apply as a top dressing, side dressing, or work into soil for outstanding results. Recommended for household plants, urban gardens, lawns, golf courses, nurseries, and greenhouses.