Feb 12, 2012 THE SECRET TO ORGANIC SOIL MIX Organic Soil Mix 1 wheelbarrow-load Vermiculite 1 wheelbarrow-load Peat Moss 1 wheelbarrow-load Aged Manure 2 4-inch pots Blood Meal 2 4-inch pots Rock Phosphate 2 4-inch pots Green Sand After a couple years of working on organic farms, and managing a greenhouse, I have a clear understanding of what makes a successful soil mix. In the diagram above I extracted the basic ingredients to illustrate the raw materials. The option to use comercial pre-packaged potting soils are widely available at nursery and garden supply stores, but you can also make your own potting mix! Making your own mix allows you to control the types and proportions of ingredients, and to customize your potting mix to meet your needs. Also, Conventional growing media that contain synthetic wetting agents and standard fertilizers cannot be used in organic production of field transplants, container plants, and greenhouse crops. Acceptable growing media can be compounded from a wide variety of approved materials. The six ingredients I use are all acceptable for organic use. When starting plants from seed the soil should be high quality | Rich in organic matter, loose for easy root growth, fast draining, yet capable of holding moisture, and free of pathogens and weed seed. Peet moss | A large absorbent moss that grows in dense masses on boggy ground, where the lower parts decay slowly to form peat deposits. Peet moss holds moisture, adds nutrients, and increases soil acidity. Vermiculite | A mineral containing mica used as a medium for starting seedlings and root cuttings. The medium supplies plants, water, and air pockets within the soil helpful in growing and developing dense root systems. Also mixed with seeds to facilitate distribution and planting. Aged Manure | Manure is fresh for the first year after being produced by the cow, horse, goat or whatever. It becomes “aged” after a full year of sitting around in a pile. Fresh manure, when added to a garden with plants can actually burn the microscopic roots of plants because it is so acidic. That pH changes after that first year of sitting around and becomes a valuable amendment to the soil. Blood Meal | A dry, inert powder made from blood used as a high-nitrogen fertilizer and a high protein animal feed. It is one of the highest non-synthetic sources of nitrogen. Blood meal is completely soluble and can be mixed with water to be used as a liquid fertilizer. It usually comes from cattle as a slaughterhouse by-product. Rock Phosphate | A good source of Phosphorus, Calcium and other trace minerals. Will not leach out of the soil, and will remain until taken up by the plant's roots. Green Sand | One of the best sources of potassium (iron-potassium silicate). It comes from sandy rock or sediment containing a high percentage of the mineral glauconite (greenish-black to blue-green). Glauconite is used in water treatment as a water softener. * The National Sustainable Agriculture Information Service (ATTRA) has a great lists of formulas and guidance for preparation of organic soil mix. It is a useful reference to understand the of many different soil mix ratios, and how to tweak a recipe for diverse applications.
