Most nurseries carry potting soil designed for container plants.
Soil for container and roof garden plants should be lightweight, rich in organics and natural nutrients, and fast draining. A base of sandy soil. Organic materials, such as composted leaves or garden cuttings, to add nutrients. Perlite, pumice or other products to lighten and aerate the soil, as well as promote draining. Manure or other high-nitrogen products to add nitrogen and nutrients.