The kidneys are paired retroperitoneal structures that are normally located between the transverse processes of T12-L3 vertebrae, with the left kidney typically somewhat more superior in position than the right. The upper poles are normally oriented more medially and posteriorly than the lower poles.
Growing Comfrey in Pots. Comfrey will grow in pots (at least 3 gallon), containers such as plastic tubs, or 5-gallon plastic buckets but they do better when not grown in a pot. They have deep roots so prefer growing in the garden where they get more nutrients. The containers need drainage holes in the bottom. Add fertilizer to the potting soil.
Comfrey root is a source of the constituent, allantoin, which is a cell proliferant used in many cosmetic and dermatological preparations, although allantoin can also be derived from several other natural sources (including mammal urine) and is made synthetically as well.