Hydroponic Troubleshooting: Coco Coir

Another common reason for a deficiency that many growers unknowingly face is due to their choice of growing medium. Coco coir, in particular, can cause some major problems, so it’s worth knowing the benefits, as well as the drawbacks of your medium before committing to anything for the long term.

We’ll start with the drawbacks, because they are widely unknown to inexperienced growers, and are an obvious reason for this newsletter.

Firstly, coco coir can present high levels of sodium which is never good for sustainable plant growth. The reason salt is often present in coco coir is that a number of manufacturers soak their coconut husk in salted water to remove impurities. To prevent issues with high salt levels in your medium, ask your supplier whether the coco was rinsed in fresh water before being packaged (we like Canna’s Professional Plus Coco). If it wasn’t, you can opt to rinse it yourself. To do this, simply wash your coco in pH balanced water, until it runs clear.

A second drawback is that coco coir can prevent the uptake of calcium, magnesium and iron. The reason for this is the mediums high cation exchange rate (CEC). CEC impacts your media’s ability to absorb your nutrient solution, and then re-release positive ions so that plants are able to consistently absorb them.

What this means, is that coco coir has a tendency to remove calcium and magnesium from your nutrient solution, exchanging them with the potassium and sodium that are naturally present in the medium.

Although a significant drawback, like most problems, there is a simple solution. To combat this unwanted exchange, either replace your current nutrient with one that has been specifically designed for coco coir or supplement your current nutrient with a calcium-magnesium additive.

The benefits of coco coir are even more abundant than it’s drawbacks. It’s environmentally friendly, reusable and even has antifungal properties. Coco coir also offers quite a rare combination of excellent drainage, aeration and water retention (especially with the addition of some perlite), so you don’t need to write it off, just do your research first!