Though you can purchase commercially prepared potting soil in garden stores and nurseries, mixing your own potting mix at home can sometimes be cheaper, according to Penn State University. The proper ratio of common gardening elements can be combined to create a mixture that retains some moisture while also draining well. The specific ratio will vary, depending on if you want standard potting mix or a soilless medium for the sowing of plant seeds.
Soilless Potting Soil (for Seedlings)
Pour 2 quarts of peat moss into a gallon-sized bucket.
Top off the bucket with 2 quarts of vermiculite or perlite to ensure adequate drainage and help with the retention of nutrients, according to Penn State University.
Stir the ingredients to thoroughly mix the two mediums together. Empty the potting mix into a seed flat or pot, and moisten it before sowing seeds.
Sterilize garden soil by spreading a quart of garden soil into a pan and baking it at 180 degrees F for 30 minutes. This kills all bacteria, plant viruses, bugs and weed seeds, according to New Mexico State University. Sterilized soil can also be purchased from most garden stores and is essential to reduce disease risks among your potted plants, according to Penn State University.
Pour the sterile soil into a gallon-sized bucket.
Add a quart of sphagnum moss. This assists with water retention and soil aeration, according to Penn State University.
Mix in a quart of vermiculite, perlite or sand to boost the drainage of the potting mix. The mix is now ready for use.