Peat moss is decomposing plant matter harvested from bogs. The decaying plant matter adds nutrients to soil, improves water retention and, according to Cornell University, is fertile material. Peat moss is used in trays for starting seedlings and cuttings, while larger quantities are used as a soil amendment in lawns and home gardens. Applying peat moss properly requires tilling the material into the composition of the dirt before planting.
Apply 1/4 to 1/2 inch of peat moss as a top cover to an existing lawn using a rake, suggests The Canadian Sphagnum Peat Moss Association. Top dressing a lawn with peat moss reduces the amount of water required to keep a lawn moist.
Spread 1 to 6 inches of peat moss onto a garden using a rake and till the material into the garden bed. Cornell University Cooperative Extension recommends adding 33 percent of peat moss to a garden, by volume. Till the material into the top 6 inches of the soil.
Make a mixture of potting soil and peat moss by mixing into a pot 2/3 commercial potting soil and 1/3 peat moss, as recommended by The Canadian Sphagnum Peat Moss Association. Moss increases the soil's water retention and adds aeration to the soil.
Mulch around tree trunks using a 2-inch layer of peat moss to increase water retention and protect the tree's roots.