Peat moss is a common growing medium
available at most gardening and home improvement centers. This growing
media is made from the coming together of decomposing plant materials in
a poorly drained area, such as a bog. Peat moss is graded on its level
of decomposition and what kind of plants are in the material. There are
four different varieties of peat--hypnaceous moss, reed and sedge, humus
or muck, and sphagnum moss. Sphagnum moss has the highest quality
organic material for growing and improves the soil it is mixed into by
improving drainage and aeration.