Peat moss is the decomposed plant material of water plants that grow in bogs or swamps. Peat moss is added to soil to improve aeration, conserve moisture and provide the necessary pH levels that various plants require.
Technically, sphagnum peat moss is commercially sold as peat moss. Peat moss is the partially decomposed remains of sphagnum moss. Most of the peat moss in the United States is imported from Canada. Another common peat material is muck peat, the decayed matter of swamp plants such as sedges, reeds and cattails.
Both sphagnum peat moss and muck peat are dark and silty; both dry quickly and are grainy and fine in texture. Sphagnum peat contains tiny fibres, the remains of the fibrous sphagnum moss. Muck peat is completely decomposed with no fibres.
Sphagnum peat moss is highly acidic. This peat is added to alkaline soil to lower soil pH, improve soil aeration and conserve moisture. Sphagnum peat provides no nutrients to the soil. Muck peat is heavier and darker. It is added to raise pH levels of acidic soil and to amend the soil with minerals and organic nutrients.