Peat moss has many applications in the garden and yard. Horticultural peat is partially decayed or decomposed moss. A lightweight material, it retains many times its weight in water. Sphagnum peat moss is the most prevalent type that gardeners use, particularly gardeners in North America. Supply of and demand for peat moss remains greater than for its alternatives, such as coir, in part because of peat's versatility in the garden.
Good soil makes water, nutrients and oxygen available to plants. Soil texture, the size of the particles, plays an important role in the soil's quality. Adding peat will not change the size of the soil particles, but it helps by creating small pockets where air, water and nutrients can travel to reach the roots. Gardeners and landscapers add peat moss to soil in containers and directly into ground soil. Peat is also useful because it retains some water and holds it for the plant to use as needed.
Gardeners prefer to start seeds in peat moss rather than soil because peat helps to control moisture levels and does not surround seeds with harmful bacteria. Gardeners who start seeds in soil risk exposing the seeds to the fungi that cause damping off--a disease that rots and kills germinating seeds and seedlings. The fungi exist in most soils but thrive in wet soils. Peat is a sterile medium and does not naturally contain any fungus. Peat also absorbs excess moisture and keeps it away from the seeds and seedlings in the event of contamination. Gardeners also prefer peat because it is a lightweight, airy material, and seedling roots expand faster when they do not face the resistance they encounter in soil.
Peat moss is not an essential component of compost. However, the Canadian Sphagnum Peat Moss Association states that adding it to a compost pile helps the ingredients break down faster. Peat's role in composting is similar to its role as a soil additive in that it absorbs excess moisture and aerates the pile. The association suggests you add a layer of peat moss to the compost pile for every 4 inches of other content.
Gardeners rely on mulch to reduce moisture loss from the soil, to stabilize soil temperatures and minimize weed growth. Unlike with pine bark, peat moss does not provide hiding and resting places for slugs, snails and other possible nuisances. However, when peat moss sits on the surface of the soil, it releases its moisture into the air and dries out relatively quickly. Dried peat moss tends to blow away with the wind.
Hypertufa mimics the look and feel of tufa, a volcanic stone. You make hypertufa by mixing peat moss, perlite and Portland cement. The master gardeners of Washington State University's extension explain there are many different recipes to make hypertufa, some adding other ingredients such as sand or vermiculite. But peat moss is a key ingredient in most, if not all, recipes. Designers use molds to create containers and troughs that are porous and resist freezing. The more peat moss you add to the recipe, the more porous the final product.