If you buy commercially prepared potting soils or seed starting mixes, there’s a good chance those products contain peat moss.

Gardeners and horticulturists use peat moss as a growing medium for plants and as a soil conditioner for a few reasons. Its sponge-like structure helps to maintain a beneficial balance of air and water in the soil. Although peat moss is not rich in plant nutrients, it helps hold onto nutrients that are already in the soil so that they remain at a level where they’re available to plant roots.
Over the past several years, organizations that monitor the health of wetlands around the globe have raised concerns about the environmental impact of removing peat from the bogs where it accumulates. To understand the concerns, it’s helpful to understand what peat is and how it forms.

Peat is the partly decomposed remains of plants that build up in cool, boggy environments. Peat may be derived from sphagnum or hypnum mosses, grasses, sedges, reeds, ponds plants or woody plants.

Sphagnum peat moss is the type usually available in this region. Layers of peat build up very slowly over, about 1/4-inch in the span of one year. It has taken hundreds of years for some peat deposits to form.

In order to extract peat moss for processing and sale, producers drain the bog, remove the surface layer of living plants, allow the upper layer of peat to dry, then loosen and remove the peat with heavy machinery.

In some parts of the world, a large percentage of peatlands have been drained, mined or converted to other uses.

More than 90 percent of the peatlands in Western Europe have been lost, as well as 50 percent of those in Central Europe. In Southeast Asia, about 70 percent of peat swamps have been altered through drainage, or agricultural and forestry use.

In areas where other sources of fuel are limited, peat is extracted and burned for heating and cooking purposes.

The environmental concerns stem from the fact that peat bogs play a vital role in providing habitat for many species of plants and animals, and in cleansing and storing water. Peatlands also sequester carbon, a beneficial function that helps to counteract the conditions that contribute to global climate change.

Over the past decade or so, some sectors of the peat industry have studied ways to regenerate moss on harvested bogs, and have instituted policies for bog restoration.

For example, the Canadian Sphagnum Peat Moss Association requires its member companies to abide by guidelines that require preservation of some bogs; leaving buffer zones of vegetation; leaving an under layer of peat unharvested to encourage regrowth; and returning the harvest area to functioning peatlands, wildlife habitat or agricultural use.

In the 1990s, Canadian scientists conducted research on restoring harvested peatlands. They tested a number of methods to regenerate moss growth.

The most successful process involved leaving a layer of peat on the site, spreading shredded live Sphagnum moss over it, and covering the area with straw mulch to promote root formation of the new plants.

Representatives on all sides of the issue seem to be in agreement that revegetating harvested bogs is a positive step.

However, other research studies found that after the new moss begins to grow, there is a larger loss of carbon dioxide into the atmosphere as the mulch decomposes. Release of carbon into the atmosphere contributes to the changes that are believed to alter climate patterns.

In the end, it’s up to each individual to weigh the facts and decide whether to continue to use peat moss or to look for alternative plant growing mediums. Some gardeners are substituting coir fiber from coconut husks, leaf mold, mushroom compost, worm castings and other materials in their planting or seed-starting mixes.

A couple of companies in Washington state are developing peat substitutes made of dairy manure that has been processed in an anaerobic digester.

Organix Inc., located in Walla Walla, has announced that it will open a production facility this year to make RePeat, which the company describes as a high-value peat substitute designed for horticultural use.

Washington State University is a research partner involved in an anaerobic digester for dairy manure in Whatcom County. One of the products in development is a peat moss substitute made from the fiber solids.

These products reuse waste material that might otherwise make its way into streams and contribute to pollution.

Once they become available, gardeners will have one more choice.