Coco(coir fibre, coir, coco coir, coco fibre) is a product derived from the husks of coconuts. Visually it looks a lot like peat. Coco, when used properly, represents the best of soil and hydro in a single media. Coco can be extremely forgiving, and growth tends to be very consistent. Coco is pretty damn tolerant of over-and-under-watering. As you will see below, coco has many amazing properties making it an ideal medium to grow plants in.

Coco is almost a neutral medium, which means that aside from its limited ability to adjust pH to optimum levels, it does not bind nutrients and feeds them slowly to the plant over time like traditional “soils” do. (This means that coco has a relatively low cation exchange capacity (CEC) compared to most “soils”.) All the nutrients your plant needs to grow must be provided by you. Coco fiber does, however, create millions of tiny air spaces which are great for the roots. This is due to the large surface area of the coir particles. Think of coco as a very porous, open cell sponge; it releases water very quickly and as it drains out of the bottom of the containers, it pulls in fresh nutrients and oxygen. The medium holds water, oxygen, and nutrients in a perfect ratio for the roots in these tiny spaces. As oxygen plays an all-important role in respiration (roots pumping nutrient up to the plant), the structure of coco coir further promotes root and plant health. This factor should not be underestimated because healthy roots invariably lead to a healthy plant (and a healthy yield).

Coco also has a remarkable capacity to insulate and protect the plant’s root system in hot weather. This means that coco coir isn’t as prone to overheating, due to excessive ambient air temperatures, as many other mediums, making it ideal for warm climates. Because the root zone is cooler, there is more oxygen available for the roots to use.

Watering with coco is different than with soil. If you grow in soil, it can be much easier to “drown” the plant with too much water. Coco on the other hand is so light that there will always be more oxygen left and the plant will have a much harder time being oxygen starved. You can let the pot become dryer the first week only to stimulate root development. We suggest watering your medium until fully saturated (with at least 10% ”run-off”) and then letting your plants go from wet to “barely moist”. Coco can be used differently than this—allowing for multiple waterings a day. A grower must only let coco go from wet and fully saturated to “moist” (usually a few hours when the lights are on) before watering again. We have had consistently great results off of the former method—going from wet to “barely moist.”

Coir holds a considerable amount of water within. It also evenly distributes the water throughout the medium. This is great for growers using drip systems because you only need one to two drippers to create full saturation throughout the entire container. However, since coco holds onto water and nutrient within its structure it creates a pH buffer within the medium itself. Coco also has a natural tendency (because of its high levels of potassium contained within) to hold onto to certain salts. This tendency (which contributes to its mid to low CEC value) tends to make coco’s buffer rather difficult to bust, thus making it harder to change the pH of the medium. Do not fret though because the buffer CAN be broken. It just takes flushing copious amount of pH corrected 300 ppm nutrient solution (50% of which should be cal/mag) with Final Phase (flushing agent mixed in) through the medium before you even start to grow in it. In this way you can ensure that the pH of the solution going into the medium and the pH of the solution coming out of the solution match. (An example of this would be 6.0 pH going into the medium and 6.0 pH coming out as “run-off”. This is a VERY IMPORTANT concept to grasp when using coco-based mediums). 

Another issue (touched on above) a grower should be aware of when using coco-based mediums is that coco naturally contains a good amount of potassium, which when released into the medium, competes with some nutrients (such as calcium, magnesium, manganese, and sulfur). Therefore we will want to FLUSH the medium on a regular (weekly or biweekly) basis or water with very low ppm/EC values. Make sure to flush with 300 ppms of solution made up of cal/mag + nutrient. When flushing, we also suggest collecting and testing the “run-off” to make sure that the ppms have gone down to almost nothing, and that your pH coming out of the bottom of the containers matches the pH being fed to the plants.