When I first began studying gardening in the 1960’s, most books about perennials were published in the UK, where peat and vermiculite were the additives most recommended to convert clay into gardening soil. Since I had never heard of peat, but I did know about peat moss. I assumed that I could substitute one for the other since sphagnum peat moss is so plentiful in Canada.
In the early days of perennial gardening, many of us didn’t understand exactly how peat helped to convert clay into what the British gardening books called loam. Today we have soil scientists who can explain how clay binds with organic matter, such as peat moss, to be broken up into a workable and nourishing growing medium.
Recently, there has been a lot of buzz that peat moss is not the renewable resource that we once thought it to be. Because its harvest requires the digging up of vast tracts of wetlands, environmentalists insist that mining this organic product will deplete the earth and upset its ecological balance. Sphagnum producers have been disputing this fact vigorously. They claim that sphagnum peat moss is a renewable resource because it can regenerate itself. Ecologists disagree because that process can take anywhere from one hundred to one thousand years, during which time much wildlife will have disappeared from the region. They argue that natural renewal, to be beneficial to mankind, ought not to take so long.
In its defense, I must report that peat moss has proven to be a wonderful, multipurpose garden product. Therefore, if I were to respect the ecologists, I would have expected them to suggest a very good substitute. They have not. Up until recently, nothing had proven to be as convenient or efficient as peat moss for urban gardening, especially in situations where where compost is not always available, or where high acidic amendments are needed.
By coincidence, the exhortations of the environmentalists happened to coincide with the introduction of an acceptable, viable substitute for peat moss-as-soil-amendment. Known as coir, it is the coarse fibre extracted from the outer shell of coconuts and therefore, the ultimate renewable resource. I have used it this season, for the first time, as a soil amendment. I can report that it handles identically to peat moss, except for the fact that it does not generate any dust [to tickle one's nostrils] because it is slightly hydrated prior to use.
Coconuts supply a wide variety of edible and useful products. However, in many South East Asian countries, where it is harvested and processed, by-product, waste material from its shells accumulatied over time. In some locations, it sat for years in giant piles, while in others, it was deliberately incinerated. Until recently, there had been no use for this apparently worthless waste.
Clever entrepreneurs have now created something out of nothing by identified the organic, horticultural potential of shredded coconut shells and have begun to market it as a legitimate organic soil additive. This product carries OMRI (Organic Materials Review Institute) approval meaning it has been approved for use in organic production and processing. As a renewable resource, it has no ecological drawbacks to its use.
Researchers at Auburn University and University of Arkansas compared peat and coir as soil amendments for horticulture. They found that coir performs on par with peat. In addition, both its high water retaining capacity [ten times its weight] and excellent drainage are equal or superior to sphagnum peat.
Coir contains no weeds and pathogens and has greater physical resiliency (withstands compression of baling better) than peat moss. It has an easier wetability than peat, i.e. it does not repel water, and can hold eight times more air; it decomposes more slowly than sedge or sphagnum peat moss and its pH level average of 6.1 is acceptable.
At its source, coir is pressure compacted into consumer-friendly sized components in order to lower freight costs and to reduce the carbon footprint of shipping it to markets overseas. It is available in bales and in cello wrapped bricks that fit so conveniently into the trunk of small cars and stack efficiently for storage.Each brick, when soaked overnight in 3 litres [a bit more than 3 quarts] of water, will produce 9 litres [about 10 quarts] of soil additive.
Spontaneous gardeners might consider this process to be an inconvenience. However, I have solved that problem by buying a large number of bricks, which I store in my garage for future use. At the beginning of the gardening season, I hydrate as many bricks as possible and store the reconstituted coir in oversize buckets. That way, I build up a generous supply to be used as needed.