If you have a lot
of planting to do, or can't afford the price of the potting
soil mix at the garden supply store, you can make your own.
Here is a simple potting soil mix recipe for container gardening.
It is rich in nutrients, which results in a thriving container
8 parts potting
soil, with vermiculite or perlite added
1 part coarse sand (usually less expensive at building supply
4 parts peat moss, compost, rotted manure (one or all)
Combine in portions
in the amount you need for gardening, mix well, and start