Peat Moss Replacement

Overview

Peat moss has long been an important material for commercial horticulture and amateur gardeners alike. Mined from peat bogs, most peat moss sold for garden use consists of partly decayed sphagnum moss. Much of this material is many centuries old, as the decomposition process is glacially slow, and despite being a natural material, new quantities of peat moss can hardly be produced as rapidly as the original material is mined and used. Several different materials have been researched and developed that rival peat moss in quality; foremost among these are coir fiber and coir dust, both byproducts of coconut fiber production.

About Peat Bogs

Accumulation of peat in bogs and low-lying areas is the first step in the geologic process of coal creation. Peat is created as plants die and decay, building layer upon layer of dense, rotted organic matter. Unlike later stages of coal creation, peat is concentrated in layers right at the earth’s surface, easily available for mining. Peat has been used since Roman times as a heat source and absorbent material. Additionally, over 2,000 well-preserved mummies have been retrieved from peat bogs around Europe, indicating that ancient European peoples frequently used these deposits as burial grounds.

Peat Moss Properties

Relatively acidic, mostly free of micro-organisms and low in nutrients, peat moss also has excellent water-holding capacity, making it a very useful non-soil agent. In addition to being a standard seed-starting medium, peat moss is also valued for its ability to acidify and condition soil, as it improves the moisture retention and aeration of heavy soils. Peat continues to decompose very slowly when incorporated into soils, making it a useful long-term soil additive.

Environmental Impact of Peat Mining

Though the United States is estimated to have over 100 million acres of accessible peat bog, most peat moss for horticultural use comes from western Canada. Areas of Germany, Ireland and Sweden are also heavily mined for peat. As a primitive fossil fuel, peat has a fairly high energy content; recent research conducted on the carbon sequestration of peat bogs suggests that intact peat bogs may be more significant carbon sinks than even dense stands of forests. When mined for use in horticulture or to be burned in home hearths, as is still a common practice in Ireland, peat may release more elemental carbon into the atmosphere than previously thought. Additionally, because bog accumulation is thought to occur at the rate of ¼ inch of new peat per year, the volume of peat removal from deposits far outstrips the creation of new material for harvest.

Coconut Fiber and Coir Products

The Sri Lankan industry of processing coconut hull fiber into exportable products has led to greater interest in using one of its byproducts as a peat replacement. Longer fibers are used as a stuffing material for cushions as well as in the manufacture of brushes and twine products. Traditionally, shorter fibers and the smaller dust-like particles left behind were discarded as waste. Tests performed by Australian and European university researchers in the 1970s and 80s demonstrated that these coir industry byproducts performed at least as well as peat in soil-less mixtures for starting seedlings and growing plant starts.

Coir in Comparison to Peat

Like peat moss, dry coir fibers at first repel water. Once thoroughly moistened, however, coir retains water as well or better than peat. Alan Meerow, an associate professor of horticulture at the University of Florida, performed comparison testing with a range of plants in sphagnum peat, coir and another soil-less mixture composed mainly of Florida sedge peat. Plants growing in sedge peat performed less well than plants growing in either sphagnum peat or coir; Meerow’s experiments also suggested that seedling root growth is somewhat more vigorous in coir mixes than in sphagnum peat moss mixes. Experiments by researchers at other universities have been less conclusive, and many researchers report widely varying degrees of sterility and nutrient content in coir depending on its source and year of production.

Keywords: peat moss replacement, sphagnum peat alternatives, coir peat replacement, sustainable peat substitute

About this Author

Michelle Z. Donahue lives in Washington, D.C., and has worked there as a journalist since 2001, when she graduated from Vanderbilt University with a B.A. in English. She first covered politics as a reporter for the weekly Fairfax Times newspaper, then for the daily newswire Canadian Economic Press, where she reported from the U.S. Treasury. Donahue is currently a freelance writer.