Coco coir is made from the residue of the extraction of long fibers from the husks of coconuts. Peat moss is a dead layer under living sphagnum moss growing on top of bogs in North America, Ireland, Scotland and northern Europe. Peat moss is a traditional soilless growing medium. Coco coir, which looks like peat moss but does not contain sticks or twigs, has become popular soilless growing medium in recent decades.
Fibers extracted from coconut shells have long been used to make mats, brushes, twine, filters, and stuffing for mattresses and upholstery. The extraction process yielded short-fiber dust called pilth, the basis of coco coir, which was considered waste until the 1980s.
The cells of sphagnum moss can hold up to 20 times their weight in water so the plant can survive dry conditions. The dead, decaying layer under the living surface of sphagnum moss in a bog or fen is called peat moss or peat.
Sri Lanka, which harvests 2.6 million coconuts annually, is the largest producer of coco coir, followed by the Philippines and India. Efforts are under way to establish a coco coir industry in Mexico.
Most North American peat moss comes from 40,000 acres of Canadian sphagnum bogs; it also comes from fens, marshes and wetlands in Alaska, Florida, Michigan, Minnesota and 13 other states. It has long been harvested from bogs in Ireland and Scotland.
Coco coir may be contaminated with animal manure, a problem in India where cows roam freely. Fresh water is used to extract fiber from ripe coconuts; if the coconuts are not fully ripe, they are processed with brine, which can cause excess salinity in the coco coir. Coir is more expensive than peat moss in the U.S. because of the cost of shipping it from Asia. Using coir may require cutting back on potassium in fertilizers and adding nitrogen.
Peat moss is acidic with a pH of 3.5 to 4. Some plants like that level of acidity, but if your plants don't like it, you may have to add limestone to raise the pH. Peat moss sometimes contains bacteria and fungal spores that can contaminate plants. Peat moss attracts snails that show no interest in coir.
The pith from which coco coir is made contains high amounts of lignin and cellulose that prevent it from decomposing and shrinking. It holds more water than peat moss, but doesn't hold it as long. Coir has a pH of 5.8 to 6.8 so limestone is less often required to adjust the acidity.
Peat moss is said to soak up to 20 times its own weight in water, which it releases slowly. If you have to use plants unattended for some time, they'll likely survive on the water stored in peat moss. While being acidic may be a disadvantage to raising some plants, it is an advantage if you use tap water that is alkaline, which tap water often is. Peat moss is less expensive than coco coir.
Coir from green coconuts is white or light brown in color. To avoid possible problems with salinity, buy dark brown coir that comes from fully ripened coconuts.
Light colored peat moss is younger and has more large pores; it holds air better than older peat moss, which is darker in color.
There are few environmental issues with coco coir, although critics note that putting land and resources in developing countries into the production of coconuts to produce fiber as a growing medium for the developed world takes land away from the vital production of food. In some places, people go without eating while land is used to grow coconuts.
Much of Europe's peat has been used to fuel power plants, and peat moss has long been a favorite of European gardeners. A peat bog may take 10,000 years to develop. British gardeners are said to use 2 million cubic meters (2,632,000 cubic yards) of Irish peat a year, affecting wildlife habitats and the weather. Environmentalists and others are concerned that unregulated stripping of sphagnum bogs in North America will cause similar problems to the natural environment.