Hello Russman, Potting soil varies in content and quality. High quality potting soils contain more nutrients than most unamended ground soils or sands, and may be able to sustain young seedlings without additional fertilizer. Organic potting soils usually contain a combination of sphagnum peat moss, composted humus and sandy loam to aerate the soil. Nutrients may come from bat guano, earthworm castings, fish or seaweed meal and added microbes or fungi. Certified organic potting mixes name the certifying body. Nonorganic potting mixes often list the mineral content and ratio of nitrogen, phosphorus and potassium in the added fertilizer. If specific ingredients are not listed, the manufacturer should provide the material data sheet upon request. Also..... Basic mix consists of 1/3 compost, 1/3 sand and 1/3 potting soil. You don't want much more compost than this because it may be too rich in nutrients, with not quite enough air if it gets too wet.
