University of Vermont Extension
Department of Plant and Soil Science
WHAT IS PEAT
Dr. Leonard Perry, Extension
University of Vermont
Most of us take our gardening for
granted or are too busy to stop and think about why certain practices
where certain products we use come from.
One of our main gardening staples, peat moss, has interesting origins
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
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
stores. Most of our peat moss comes from
Canada, much of it Quebec, although some in the Midwest and South comes
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
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,
Peat from Canada is harvested only
after environmental analysis and impact, using sustainable methods,
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
Peat mosses mainly are found in bogs
and wetlands in the northern hemisphere, covering about two percent of
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
peatland can be returned to an ecologically balanced system in only 5
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
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
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
(lacking oxygen) sphagnum bogs. The
acidity dissolved bones, but preserved skin, clothing, and even hair
thousands of years.
Most of us know peat moss for its
horticultural uses to provide better soil aeration, add substance to
to help the soil hold nutrients more effectively, and to help retain
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
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
garden or bed along with the peat moss, then rake or till in both at