First published in the Summer 2023 The Garden Path. If you would like to get The Garden Path, we invite you to JOIN US as a member.

Coco Coir by Mary Lee Minor, Region 7

Back in February while potting up paperwhite narcissus, two circular cakes of coco coir were included in the planting project. The directions were to add water. These cakes expanded to fill a 2-quart container. A moist and airy, rich and dark heap of material emerged.

This medium brought curiosity. Our yard compost and this coir have many of the same characteristics. Both have spongy texture, expanding air spaces and the capability to hold moisture. Backyard, garden created compost breaks down rapidly in the soil. This brings a need to reapply more each growing season. Coco coir is described as lasting years in the soil.

What really is coir? It comes from or is actually the husk fibers torn from the coconut shell. Tiny grains of coir are extracted and then pulverized becoming packageable. Coconuts go through a retting process, a curing method which naturally decomposes the husk pulp. Traditionally the husks were immersed in water for 6 months or longer. Today retting can be completed in a little over a week using modern mechanical techniques.

Next the coconut fiber is removed from shells with steel combs in a process called defibering. Once the coir is gathered from the husk it is dried in the sunlight. This takes months and the material lies on a concrete floor, which reduces the moisture to about 18% of what it was originally. The coir is then pressed into bales, bricks, discs such as I used, or coir pots, with automated hydraulic compression. It is of course bagged as loose mulch, too.

In reading about this coco coir I learned that it has a high lignin content. Lignin is a substance that along with cellulose forms the main makeup of woody tissue. Lignin does not break down readily. In the soil then, lignin is the secret to coir's longevity. Its life span ranges from 5 to 10 years. Coir out-performs peat moss, vermiculite, and perlite as a soil amendment. It does make you wonder why the gardening world has not marketed this coir abundantly. Does the world have a limited supply of coconuts? If so, planting more palms might be an entrepreneur's paradise. Research suggests that technology in the last few decades is making coco coir available anytime and anywhere in the world. And it is abundant. And further, coir is a disease-free growing medium which retains moisture yet never becomes wet or soggy. That makes it nearly perfect for seed starting. Coir is free of weed seeds, diseases and pathogens. It has antifungal properties. Coir has other virtues including its ability to hold seven times its weight in water, it cannot be compacted and that aeration property fosters root development; coir does not become waterlogged. Most insects will not settle into the coir. Using coir in our gardens could be a good move when you consider that peat moss comes from peat bogs which will one day be exhausted.

Coir is a renewable resource, repurposed from coconuts. It is soilless. In the meantime it is my hope that seed starting efforts in the garage will bring high success. Without statistics right now, I recommend you find this material and make your own observations about its efficiency.