That's right! You can grow super dank mary jane in nutrient inert coco coir to achieve the control of hydroponics with a more traditional soil-like potted medium.
Pros and Cons of Coco for Cannabis
Benefits of growing cannabis in Coco Coir
- Even when saturated, maintains 30% air ratio making it very hard to over-water
- Coco is not living, has no nutrients in itself, and therefore plants get exactly what you feed, as you feed. No waiting on microorganism to break down the soil for nutrients.
- Unlike soil there is not a delay in taking corrective action in nutrient levels.
- Reusable: rinse and repeat! Since we supply the nutes, you can easily use coco cori 2-3 times before it has too much plant matter (old roots) to keep going.
- Massive yield. Hydroponics is loved for good reason...
Downside of Coco Coir
Although inert, it has a high cation exchange meaning it steals calcium and magnesium, trading potassium and sodium. This can lead to both calcium deficiency and or potassium toxicity. The fix is simple but critical 'buffering' step after rinse, which I will cover below.
Over the course of the grow you will need to continue a slightly elevated rate of this supplement to maintain that buffer.
Supplies
- Coco coir pith
- I assume you;'re getting by the bale, you can get pre-rinsed and buffered but hard to ship of not local
- "pith" is just the spongy material in plants
- Perlite #3 or larger
- CalMag (Calcium Magnesium) to buffer
- Feed of choice (General Hydroponics has mineral and organic lines, Foop! offers organic feed)
- Cannabis Seeds or Clones
Preparation
There are 4 main steps when using Coco bales, and I'll break down each one.
- Rehydrate the coco pith
- Rinse the coco pith from any existing salts and finer dust.
- Buffer the coco with a high CalMag PH neutral water
- Mix down the coco to a 2:1 - 1:1 ratio with perlite giving you a 66/33 - 50/50 mix.
My personal choice of tooling is an oversized cooler with a drain plug, as you'll see why in the next few steps.
Hydrating Coco Coir / Coco Pith bales
The 'bale' is a compressed dried brick of coco. It's going to expand like mad once we start adding some water. A 5 kg brick should yield 6-8 full pots of mix once perlite is added.
Try to crack or chip the brick if not hydrating it all. Do not cut or saw, we want to avoid the fine dust.
Rinsing coco coir is critical
Before buffering, you should soak and rinse the coco a 2nd time, and drain well, this removes extra salts and the finer dust that is not our ideal substrate.
Buffering Coco to prevent toxicity
Buffering just means to provide an excess of the nutrients we want available (Calcium and Magnesium) to overwhelm and replace the salts we don't want (like potassium and sodium). In science it;'s known as diffusion, we move calmag from areas of high-concentration (the water mix) to areas of low concentration(the coco), and the inverse happens for the salts naturally in the coco, which get pulled out into the water.
This step needs to soak for several hours, and be repeated 2-3 times.
Mixing Coco with Perlite
Even though Coco has a amazing natural protection to over saturation, adding perlite can double the mediums ability to hold moisture and oxygen -- win:win!
Most growers use a 2/3:1/3 mix, some go so far as a 50:50. I'm personally the former. My super-scientific method is to add roughly half the amount of coco in perlite, by volume.
1 full tub of rinsed and buffered coco 
half tub of organic (non fertilized perlite)
mix it all up! 
The final Product
The final product is something that looks damn close to potting mix, but remember - it has no nutrients, so next step is growing and feeding!
Grow
Coco is the perfect medium for automated feeding in something like an Autopot or Drip irrigation.
I won't go into this step, as it;s mostly typical of other methods.
** Be sure to modify feed charts to include CalMag if not prescribed!** 1-2 mg / gallon is my usual dose
Clean-up and Re-use
As I mentioned in my intro, one of my favorite aspects is the re-usability of Coco. I use mine 2-3 times depending on how much root/plant remains are left after rinse.
Start by rinsing the root-balls in some water to loosen the coco from the roots.
Remove the cleaned roots and you;'re left with a slurry of coco and perlite water.
using a mesh filter or strainer, you can scoop the floating perlite from the top once things settle,
and collect for the next mixing.
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