In this article, we will explain why growing media based on coconut coir so often comes in compressed form, give more insight on the rehydration process, and go over coco coir buffering and washing. We will answer here some of the questions that many of the first-time users of coir substrate have.
Coconut coir has one amazing property that makes it stand out among other growing media: it is easy to compress when it is dry. After drying out for a long time, coconut coir is usually compressed into blocks of different sizes using special machinery.
Compressing growing media makes it possible to transport significantly larger volumes of substrate for the same cost. When coconut coir arrives at its final destination, users add water to it, therefore rehydrating and expanding it to its final volume. Compression ratio varies from product to product, but can be anywhere between 3 to 14 times.
Dehydrated and compressed form also allows growers to decrease physical labour as transporting light and compact substrate around the plantation or greenhouse is much easier than substrate in loose and bulky form.
Amount of water needed to fully rehydrate the compressed coco coir substrate is around 70% of its final volume. However, the exact amount of water depends on the product purchased. We provide our clients with detailed guides on how to rehydrate each of the coconut coir substrate compositions, sizes, and types.
Naturally, coir has high levels of salts like sodium, potassium and chloride. Some plants are very sensitive to high amounts of these salts so corresponding treatment is required. Washing coir gets rid of some of the K, Na and Cl salts present inside it, therefore also lowering the EC (electrical conductivity) of the substrate to some degree. However, it’s hard to change nutrient concentration inside coconut substrate itself thanks to its high cation exchange capacity (CEC), and additional buffering is required.
Generally, having high CEC of substrate is very beneficial for the plants. It means that it has many exchange sites and easily exchanges cations between these exchange sites and substrate solutions. Thanks to this property, a backup of nutrients helps plants when nutrients are low in the substrate solution. This becomes problematic when the exchange sites are full with harmful salts. Coir can then bind calcium, magnesium, and other useful elements, making them unavailable to plant for quite some time.
This problem is very easily solved with buffering (treatment) of coco coir growing media with Calcium (Ca) and Magnesium (Mg) solution. Buffering reduces concentration of K and Na in substrate to a minimum by replacing them with Ca and Mg in the exchange sites. It is easy to do on site and we provide our clients with full support and guidelines for the buffering process. In addition, we provide already buffered products that are ready to use both in compressed and loose form.