University of Vermont Extension 
Department of Plant and Soil Science

Anytime News Article

 
WHAT IS PEAT MOSS?
 
Dr. Leonard Perry, Extension Professor
University of Vermont
 
Most of us take our gardening for granted or are too busy to stop and think about why certain practices work, or where certain products we use come from.  One of our main gardening staples, peat moss, has interesting origins and uses.
           
To begin with, the terms "peat" and "peat moss" often are used interchangeably although they are slightly different.  Over thousands of years, plant materials submerged under water in bogs have broken down to form a type of soil called "peat".  Most common is peat from the sphagnum moss plant.  Don't confuse the peat from dead plants with the actual sphagnum moss from living plants.  Sphagnum moss often is seen as a liner for hanging baskets.  This moss grows on tops of such wetlands, and is harvested first, then the peat below.  Even sphagnum is not all the same, with over 150 different species.  Peat can derive from other plants, such as sedges or reeds, and would be labeled as such although these are seldom seen.
           
Peat is what firms harvest, often drying out the bog temporarily so they can suck up the peat with vacuums.  The peat is then dried further, screened, and compressed into the bales of peat moss--this final product-- that we buy in stores.  Most of our peat moss comes from Canada, much of it Quebec, although some in the Midwest and South comes from Michigan. 
           
Some other products made with the peat moss are peat pellets, used for starting seeds, and peat pots.  These can be planted directly in soil where they will dissolve, enriching it.  If using peat pots, make sure and break off the rims above the surface, or bury them completely.  Otherwise, the peat pot rims will wick moisture from the soil and from around roots.
           
Some reports in the past have mistakenly attributed a rare skin disease causing lesions to peat moss.  The fungal disease "cutaneous sporotrichosis" actually has only been identified with sphagnum moss, not peat moss.
           
Peat from Canada is harvested only after environmental analysis and impact, using sustainable methods, with conservation and bog restoration in mind.  You can learn more about the whole process of harvest and conservation at the Canadian Sphagnum Peat Moss Association website (www.peatmoss.com).
           
Peat mosses mainly are found in bogs and wetlands in the northern hemisphere, covering about two percent of the land on earth, about one billion acres.  About two-thirds of the world's supply is in Russia, and one quarter in Canada.  About two-thirds of the world's wetlands are peat, and about seven percent of the peat has been used for agriculture.  Of the peat in Canada, only about 0.02 percent is harvested yearly, or about one million tons.  At the same time, an estimated 70 million tons of peat is being created by nature each year there.
           
Even though peat in virgin bogs may date back hundreds or thousands of years, research has shown that harvested peatland can be returned to an ecologically balanced system in only 5 to 20 years after harvesting.  Peat itself forms at a rate of an inch every 15 to 25 years. 
           
Even though peat bogs cover large areas of Finland, Ireland, Scotland, Germany, and Sweden, many are concerned there about over-harvest, depletion, and using alternatives instead.  Peat has been harvested in northern Europe for many decades for many uses.  It has been cut from bogs in "bricks", dried, and used both for insulation and burning for heat.  Peat moss also is a key component of growing mushrooms.  The living sphagnum moss was used as a wound dressing in both World Wars, due to its absorbent and antiseptic qualities.  The latter comes from its acidity preventing growth of bacteria and fungi.
           
Perhaps most interesting is the finding of several ancient human bodies, preserved well, in cold and anaerobic (lacking oxygen) sphagnum bogs.  The acidity dissolved bones, but preserved skin, clothing, and even hair for thousands of years.
           
Most of us know peat moss for its horticultural uses to provide better soil aeration, add substance to sandy soils, to help the soil hold nutrients more effectively, and to help retain soil moisture without being waterlogged.  It also is a major component of soilless potting mixes.  You can add it to holes when planting perennials or woody plants.
           
If adding to a whole annual flower bed or vegetable garden prior to planting, you can figure that a 3.8 cubic foot bale spread one-half inch deep will cover about 180 square feet.  If spread one inch deep, this bale will cover about 90 square feet.  If adding to a whole bed or garden, make sure and test the soil afterwards.  The peat moss will acidify the soil, meaning some lime will be needed in many cases. Many gardeners spread compost on a garden or bed along with the peat moss, then rake or till in both at the same time.

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