Fertilized potting soil is available from most gardening supply stores in various size bags. Potting soil is useful for indoor and container vegetable gardening, but it loses its aeration and fertile properties after about one growing season. Fertilized potting soil can be composted or turned in to the garden after use, but it is cost-prohibitive compared to other soil additives for in-ground gardening use.
Potting medium for starting vegetable seeds should be loose and crumbly, with a fine texture that allows for easy drainage and provides lots of airspace for new roots to grow. Commercial fertilized potting soils vary widely in their density and component elements. Some are very dense and contain large chunks of bark, stones, or other matter.
The University of Missouri Extension advises that a mixture of 1 part garden soil to 2 parts vermiculite as a home-made seed starting medium. Fine, screened fertilized potting soil can be substituted for the garden soil. If the potting soil already has perlite or vermiculite in it, you can reduce the proportion of vermiculite.
Fertilized potting soil can be used as a growing medium for a container vegetable garden provided that it is fine-textured and loosely structured enough to provide for adequate drainage. The Texas A&M Extension recommends a soil-less mix of peat moss, vermiculite, limestone and fertilizer rather than a dirt-based potting soil. Carefully check the label of your fertilized potting soil to determine its components, and assess its structure and texture once you've opened the bag. If it has large pieces or is very dense, sift it and mix it with vermiculite and peat moss before filling your vegetable containers.
In-Ground Vegetable Garden
The components of potting soil degrade through the course of a growing season, according to to the Iowa State University Extension. After one year of use growing vegetables in containers or as seed-starting medium, used potting soil can be turned into the vegetable garden to help boost soil tilth and add organic matter, or it can be incorporated into the compost pile.
Fertilized potting soil can be incorporated into garden soil to improve its structure and fertility. However, it is usually a very expensive method of amending soil. Topsoil, compost or composted manure, peat moss and other soil structure and fertility additives are available in bulk quantities for significantly lower prices than the usual small bags of potting soil.