Peat moss is an excellent organic conditioner for soil and when used in proportion to the type of earth being treated can enhance plant growth. One of the ways this is accomplished is by helping to retain water that supports root growth.
Sphagnum bogs are a source of peat moss and is widely available as a packaged product. Not only does it absorb moisture, it also lightens soils to allow better air flow for root development as well as helping to retain essential nutrients. For outdoor use, it is particularly useful for treating heavy clay soils, as well as increasing the acidity of alkaline earth. When using peat moss, it is helpful to know the initial pH of soil to calculate the proportions of sphagnum to earth.