Making potting soil is a simple process. Using your own mixture of potting soil is beneficial because you know exactly what is in the soil, you can adjust it manually for specific nutrient content, and you can make larger quantities inexpensively. Potting soil mix is more granulated than standard garden soil. This makes it ideal for starting plants from seed and use in container gardens that require more aeration and drainage. Standard potting soil mixes are soil based.
Add 1 gallon of sterilized loam soil to the bushel basket. Do not use garden soil from your own garden; it may contain pests, disease and weed seeds.
Add 1 gallon of moistened sphagnum peat moss, 1 gallon of coarse sand and 1 gallon of vermiculite. Mix thoroughly using a small hand trowel.
Test soil for proper texture. Potting soil mix should be loose and drain well. Potting soil mix that feels gritty is too sandy, and you should add small amounts of sphagnum peat moss. Potting soil mix that feels sticky too closely resembles clay soil and will not drain well; if this is the case, add small amounts of sand. Continue adjusting your potting soil mix until it feels light and airy.