Skip to main content

You are using an outdated browser. Please upgrade your browser to improve your experience and security.

3 Disadvantages When Growing in Coco Coir and Their Solutions

Category:
Posted: 4 months ago

All growing medias have specific traits that carry benefits to cultivating in them, but they all also carry disadvantages. Coco coir is one which has more benefits than drawbacks, but because of misinformation these coir growing problems have intimidated many growers from touching coir. The fibrous texture of coco coir comes from the husks of coconuts grown across the globe. Coirs is relatively new growing medium that has a huge popularity amongst growers. When selecting a growing media, it has to be done with careful consideration on the type of grow you want to achieve.


In its original form just after drying coco coir would not be ready to grow in and a range of processes would have to be applied before it can be good to grow in. You have to bare in mind that natural coco husk has an unbalanced mineral saturation which effects EC, PH and CEC. The funny thing is that these 3 measurements are related and will have an effect on each other when processed.

Most Coco Coir on the market these days is washed, buffered and steam sterilized before it is sold. However, it may not be nutrient buffered so please make sure you know exactly what your buying. If you know it has not been buffered you can use SHOGUN CalMag to buffer the media to help stabilize the pH within the media and reduce the sodium and potassium content.

To start off with you want to make sure you don’t use bad quality coco which can be unprocessed and saturated in unwanted minerals like sodium. Other types of poor coco could be due to improper processes of rinsing, buffering, steaming and sterilizing with toxic chemicals. This effects the characteristics of coco and can make it even harder to grow in after changing pH and EC. Furthermore, the use of harsh Chemical agents to eradicate pathogens and disease can lead to residues which the plant can take up and accumulate in the flowers. If you are worried about your media containing pathogens we advise coco growers to sterilise their media themselves. Ideally with steam, but this is not always viable and therefore with economical viable solutions like silver bullet roots that do not produce any residue. It is however a good idea to reintroduce mycorrhiza fungus that has also been wiped out, to help encourage root development. Infestation can also be an issue in coir, due to nitrogen being released from the coir as it decomposes, coco can be the perfect little hotel for fungus gnats it is vital to use a good sterilizer and good hygiene practices in your grow room.

Potassium toxicity & cal-mag deficiency

As Coco has a high cation exchange capacity, when you feed your plant with calcium or magnesium, the minerals may never be available to your plant, as it will be exchanging it’s self for sodium and potassium. As explained in the washing versus buffering blog article, coco coir substrates prefer to bind to magnesium and calcium compared to sodium and potassium. This means that your plant, when given a normal dose of Calmag, will actually have sodium and potassium available to uptake as opposed to the desired Cal-mag combination.

By buffering the coco completely until saturation, you can guarantee any further CalMag that that is fed into the media will not be absorbed by the saturated substrates but will sit in-between the spaces of the media ready for uptake by your crops. Remember when you buffer the media with a calmag solution you have to wash the sodium and potassium out of the media other wise you will get toxicity. If you are half way through your grow and did not take this precautions, taking a calmag and foliar spraying it on your crop leaves can be a more efficient way to directly remedy the problem. Make sure you do this at low light levels or this can results in burning of the leaves. The addition of a wetting agents will aid with the uptake of calcium via the leaves. In addition foliating calcium is a great Idea as it is quite an immobile mineral, which means it has a lot of trouble moving from one are to another regardless of media.

You see although you have remedied the calcium nutrient lock out problem, you start an over supply of potassium problem. There are 2 things you can do to handle  this, the first would be for you to wash out your media again after buffering. The second is to use PK warrior for only one week in week 3 (Day 21) of the flowering  cycle (short days). Although it makes the process longer we always suggest to wash it out once again, so that you can start your grow on a canvas where you don’t have to modify measurements as much.

Absorption and over watering Coco Coir

Coco substrates are not particularly porous so can be difficult for a solution to break the substrates surface tension from hand watering. As a result many growers soak their coco with far too much solution with the anticipation of it being slowly saturated into the substrates. This method of wetting can lead to wasting much more nutrients through run off at the bottom of the tray. In addition this soaking may not even be good for you plants, a wet media means the space for roots will be tighter and where there is water there is no air, which is vital for healthy roots.


In reality coco can be tricky and can still appear wet without actually being fully saturated with feed to give to the plant. There is a need for the plant to go through a wet dry cycle to encourage the plant to search for water with its roots and therefore improve development, suggesting that media does not need to be wet, but just moist!

Alternative methods include using a moisture sensor that activates irrigation systems when the moisture reaches a particular level. Also using a speed set drip system, or lowering the pressure and speed of watering to allow the coco substrates to soak the nutrients. This can still produce run off at the bottom and may still not fully saturate your coir with the feed it needs. Shogun Aquazen is a revolutionary technology that makes dry coco substrates soak up nutrients on impact, like a sponge. The special ingredients in this are only found in SAMURAI COCO and are responsible for the lateral distribution of the liquid feed.

  • Superior Product
    Made in Britain
  • Supercharging Plant
    Growth Innovation
  • Research Driven by
    Dr. Callie Seaman
  • Independent 3rd
    Party Lab Tested