Coco coir, in its various forms, is increasingly used by gardeners as an addition to soil, or as its own growing medium. One of its key selling points, as an alternative to sphagnum peat, is that it is an environmentally-friendly substrate.
It’s not just that the fibres can last for years without degrading. Coconuts are an annual crop. Unlike peatlands, which take centuries to form, coco coir is self-sustaining.
It’s no wonder therefore that a growing number of gardeners are interested in knowing more about how they can reuse coco coir effectively.
In answering this question, it’s worth looking at how pure and mixed-coir can be maintained before and during reuse, as well as external factors that may affect the value of used coir in future projects.
Reclaiming coir from a mixed substrate
Coco coir is an inert growing substance, with a pH level near neutral. Because it is essentially a ‘blank slate’ for anything put in it, it gives it a distinct advantage over other substrate types as a candidate for reuse.
However, maintaining this potential will require work. While coco coir can be used as a soil substitute, it’s generally not advised. As a result, coir is often mixed with another substrate, such as regular soil or perlite.
Removing unwanted debris
When the mixture is no longer required, other materials will remain that the gardener may wish to remove. For example, debris from the roots of a plant can result in a drop in the ability of the material to absorb water. The porous nature of coco coir is a desirable trait. However, trying to retain this quality in used coir can be problematic.
It is possible to help the process of removing plant debris by adding an enzyme once the growth cycle of the plant has concluded. Enzymes are organic catalysts that work to speed up a chemical reaction – in this case, the breakdown of residual plant material
Plan to recycle your coco coir
If you plan to stretch the life of your coco coir supply, it is probably best to use what you have with the intent to reuse in mind from the outset. Mixing coir with another substrate will reduce the amount of coir being used at any one time, meaning more can be kept in reserve – providing the gardener with value for money, and giving the plant an opportunity to grow in an environment that isn’t completely bereft of nutrients.
Retaining the benefits
But will the mixture be of use at the end of the growing cycle? Depending on how the coir is mixed, and the types of plant nutrients introduced to the soil during the growing season, the pH balance of the soil may be subtly altered. The salt content may also have changed.
Excess salt can be removed by flushing the mixture with distilled water, although you run the risk of losing beneficial nutrients.
Another option is simply to add fresh material to the mix, which is a good way to boost the water absorption capacity of used coir.
In addition to saving money and resources, the reuse of coconut coir can also be a boon for future gardening projects. This is due to coconut coir’s capacity for retaining ‘good’ microorganisms, such as variants of the Trichoderma fungus, while also protecting against harmful pests, weeds and bacteria.
Retaining these types of organisms means eschewing any kind of treatment to prevent or kill off pathogens.
When coco coir is being prepared for use, prior to sale, the material may be coated with chemicals or steamed to remove potential infestation.
While this can prevent the introduction of harmful substances, it strips the soil of beneficial elements, like good fungi. In addition, there is also the possibility that the cellulose in the coir fibre cells could collapse. This would cause the fibres to break down.
Heat is also effective at killing unwanted microorganisms. However, introducing heat artificially, through a mechanized source, also puts the coir fibres at risk of collapse.
Alternative uses for used coconut coir
If you feel that the challenge of reusing coconut coir for a similar project is too much, you can always repurpose it elsewhere in your garden.
For example, used coir is an excellent agent for improving ‘difficult’ soil types: it can break up tough clay, and makes it easier for sandy soil to retain water.
Don’t throw away your coconut coir!
As it is organic matter, finding a use for coconut coir after it has been through a growing cycle makes more sense than simply throwing it away. As coir fibre is extremely hardy, it does not decompose quickly — the process can take several decades.
While it is biodegradable, if coconut coir finds its way to a landfill site it will simply sit there for many years.
A brief note on storing unused coconut coir
If you do intend to mix coir with another substance and end up with leftover coir to put in storage, be mindful of how you choose to do this.
Coir in its pre-hydrated state is flammable and presents a suffocation risk in large volumes, as it is also very good at absorbing air in enclosed spaces.
In addition, it can absorb moisture from the surrounding environment very easily. Damp coir left to sit could end up infected with mildew or mould.