Peat moss takes thousands of years to form and stores massive amounts of the earth’s carbon, making it a pretty unsustainable growing medium or soil additive for gardeners. In Organic Gardening magazine, Cristina Santiestevan breaks down the numbers behind peat moss production in Canada, the source of most peat U.S. sold in the United States:
At the average rate of 0.6 to 0.7 millimeter per year, Canadian peat bogs add 6 to 7 centimeters in depth (less than 3 inches) over the course of a century. It will require 3,000 years to amass the 2-meter depth needed to justify the costs of extraction. Under these conditions, a fully mined peat bog will not be able to support a second “harvest” for at least 3,000 years.
Can a resource that renews itself this slowly ever be considered sustainable? If we balk at cutting down 500-year-old trees in old-growth forests, should we accept the extraction of 3,000-year-old sphagnum moss from peat bogs?
Our prescient sister publication Mother Earth News touched on this issue a couple of years ago, pointing out the environmental costs of peat production while fielding an “Ask Our Experts” question, “Do you recommend peat moss to improve soil?”
Contributing editor Barbara Pleasant tacitly endorses using small amounts of peat in indoor seed starting mixtures, but count me among the budding gardeners who’d like to find a way around using peat entirely. I’ve seen coconut fiber, vermiculite, perlite, and even non-clumping clay cat litter mentioned as peat moss substitutes, but I don’t have any personal experience in trying these. Are there any green gardeners out there who have a preferred peat alternative?