PREMIUM SOIL BLOCKING BLEND with Organic Compost, Worm Castings, Feather Meal, and Greensand - 16 Dry Quart Bag Excellent for use in starting soil blocks. Can be used as a great potting soil also. Developed and tested to promote excellent root and stem development for your new seedlings. Made from organic compost, sphagnum peat moss, coco coir, and volcanic pumice. Then amended with worm castings, feather meal, and greensand.