Otherwise known as peat moss

Peat is organic soil that consists of rotted plants, inorganic minerals, water and air. It differs from Muck (Yes, "muck" is a technical term used by soil scientists) because in muck the organic material is decomposed beyond recognition.

Sphagnum comes from bogs in Canada, and it's usually over 90% organic.. And it's real aerated, eh? It's a bit light weight, so usually bark or sand is added to avoid the "topple factor", the technical term for when your plant tips over. When it's wet, sphagnum absorbs water, but when it dries out, it can actually repel water, which is the kiss of death. Peat must always be mixed with wetting agents, and is usually mixed with some of the items listed below.