Peat Moss Definition


Peat moss is a natural product formed from the decomposition--the breakdown and drying out--of sphagnum moss. Sphagnum moss is an essential component in the ecosystem of bogs, which are swamplike wetlands that have an abundance of decomposed moss and vegetation. Harvested peat moss has been used for many years to enhance the soil of gardens and landscapes.

Sphagnum Moss

Peat moss comes from sphagnum moss, the living part of the plant. As sphagnum moss dies off, it eventually decomposes into peat moss. According to the University of Arkansas, harvested sphagnum moss is also used for plants, as a shipping and growing medium.


Unless you have your own bog where you can harvest peat moss, you will have to purchase peat moss from a gardening store. Expect to add nutrients and fertilizer to your plantings since peat moss is generally low in nutrients. While peat moss in its dry state repels water, it must be moistened before it is mixed into soil. Once it is moist, it helps the soil retain water, and its composition lightens and aerates heavy soils. The low pH of peat moss may help to balance soils with high pH levels. Peat moss generally does not have weed seeds, and it contains very few microorganisms in its composition. This means that adding peat moss to your existing soil may not introduce weeds and disease to your garden and landscape.

Garden Uses

Peat moss is often mixed into garden soil. Its composition aerates and loosens the soil, an essential prerequisite to having a successful growing season. The aerated soil helps vegetables, flowers and other plants grow into healthy plants with strong root systems. One of the best and least-expensive applications for peat moss is to use it for starting seedlings in pots. The seedlings can grow in the pots and then be transplanted to the garden soil once their roots are fully developed. Peat moss is used in hydroponic systems in place of soil as a medium for growing plants. The peat moss supports the developing plant's roots and it holds the water and liquid nutrients around the roots in the hydroponic system.

Lawn Uses

When peat moss is mixed into lawn soils, it loosens the soil and allows more air to reach the roots. The loosened soil promotes root health by allowing the roots room to grow deeper and broader in the soil. For sandy soil, peat moss gives it a more stable composition that can add more plant and root support than without the peat moss. Peat moss in lawns also helps the soil retain its moisture and nutrients for a longer period of time--an important feature since many lawns are often in full-sun exposure for most of the day.

Environmental Concerns

Concerns arise when peat moss is harvested at a rate that exceeds its natural production. Over-harvesting of peat moss can possibly irreversibly change the ecology of bogs. According to Cornell University, the industry must maintain regulation of its usage so that peat moss can remain a sustainable resource for years to come.

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About this Author

Naima Manal's articles on health, diet, nutrition, alternative medicine, education, parenting, crafts, travel, home and garden and home improvement have appeared on eHow, Garden Guides, Trails, ConnectED, Helium and others. Manal received her B.S. degree in biology/pre-medical studies from Molloy College in 1994 and has been a freelance writer, teacher and homeschooling mom since 1993.