What is Peat Moss? Peat moss, or sphagnum moss, is accumulated bio-matter that develops over time in peat bogs. Most peat is harvested in Finland, Ireland, Sweden, Germany or Canada. The mosses grow, fall to the bottom of the bog, and form layers. At the bottom, the moss only decomposes partially, because the conditions are anaerobic. … Continue reading Should You Use Peat Moss as a Growing Medium?