Q: What is the difference in potting soil and potting mix? Which should be used on indoor plants and which in outdoor pots and which in the garden?
A: Potting mix is a blend of peat moss, pine bark fines, perlite, sand, and usually has a small bit of fertilizer. The mixes vary from brand to brand and a blend one company calls a potting soil might be called potting mix by another. In my opinion, you get what you pay for. Lower quality potting products have not been manufactured consistently and may break down faster than higher quality merchandise. I like to see a high percentage of peat, perlite and pine bark fines to use with container plants, both indoors and out.
Potting soil usually contains some native soil plus pine bark fines or composted wood fiber and perhaps some peat. When mixed with the soil in a flower bed you’ll get an excellent growing spot for outdoor flowers.