Ingredients Allowed

• When choosing the ingredients for your organic potting soil mix, there are many considerations to take into account. Organic does not limit your resources, but you do have to be a bit more picky when it comes to those resources. While many potting soil mixes are "soil-less," soil can still be used for a heavier mix, provided there are additional materials to provide good drainage. Sand, especially coarse builder's sand, can provide air spaces and add weight for top-heavy plants. Compost is commonly found in most recipes for organic potting mixes, as it holds water well and provides the plants with many nutrients. If you are making your own compost, plan at least six months in advance of when it will be needed. According to the National Organic Program, "Compost piles must maintain a temperature between 131 and 170°F for at least three days in a static or enclosed vessel system, or at least 15 days in a windrow system, with at least five turnings."
  
  Peat moss is another very common ingredient in soil mixes. Make sure to select untreated peat moss, however, and assume that any product with an unspecified wetting agent is prohibited.
  
  

Recipes

• A classic soil-based mix recipe would be composed of 1/3 mature compost, 1/3 garden topsoil, and 1/3 sharp sand. Perlite and vermiculite are two substitutes for the sand that help lighten up the mix and increase its water solubility and drainage. From the Winter 1994 issue of NOFA-NJ Organic News, Eliot Coleman provides this recipe for organic potting mix: 1 part sphagnum peat, 1 part peat humus, 1 part compost, and 1 part sharp sand (builder's). Add 1 cup greensand, 1 cup colloidal phosphate, 11/2 to 2 cups crabmeal, or blood meal, and 1/2 cup lime to every 80 quarts that you make.
  
  From the March-April 1989 issue of the Ozark Organic Growers Association Newsletter is a light seedling mix for Styrofoam flats consisting of 2 parts compost, 2 parts peat moss, and 1 part vermiculite, pre-wet. Experiment with small batches to find out what works best for your plants. Store unused potting soil mix in covered tubs in a cool, dry place.