Coco-coir is often considered a stepping block for growers transitioning from soil to more efficient hydroponic growing methods. Coco-coir is used as an inert substrate for the roots to grow in. DWC lets the roots to sit in water 24/7. In DWC hydroton is sometimes misunderstood to be a substrate but its primary function is to block light leaks, give counterweight for the plants and allow air exchange with the water reservoir.
Overview
What is Coco-Coir?
Coco-coir also called coconut fiber or simply coir is a fibrous material extracted from the shell of coconuts. It is a tough material known for its use in doormats, brushes and of course as a substrate for growing cannabis.
What are the Advantages of Coco-Coir?
- Coir has a neutral pH for growing (5.5 – 6.5)
- Excellent drainage and lots of air exposure for the roots, low risk of overwatering as with soil
- There are no nutrients, so you get a blank slate and full control from the start, much like with DWC.
- Environmentally friendly product – can be reused (although not exactly easily) and its production is sustainable.
- Has natural antifungal properties, root rot is not as much of a concern as with DWC
- Roots can tolerate much higher temperatures relative to DWC. I recommend coco for all growers that cannot maintain ambient room temperatures under 80F and water temps below 70F.
- Organic nutrients can be used, unlike DWC which requires the use of synthetic nutrients only
What are the Disadvantages of Coco-Coir
- It is messy and the fibers have a way of getting everywhere
- It is not as efficient as DWC where the roots have constant access to the nutrient solution.
- Most coco grows are drain-to-waste which uses a wasteful amount of nutrients
- Setting up an irrigation system is complex and requires more moving parts than DWC which is essentially growing directly in the reservoir tank
- Without automatic irrigation, plants must be watered frequently
- pH and EC/PPM cannot be continually monitored like with DWC
- Improperly stored coco can carry pathogens into your grow area
- Plants do not grow as quickly as DWC
- Coco needs to be sanitized between grows and replaced every 2-3 grows, which means you have ongoing costs unlike with DWC where hydroton can be reused indefinitely.
Examples of a Coco-Coir Setup
I included the pictures above to show how complex coco setups become when setting up automatic watering and drainage. Coco is often falsely advertised as being easier than DWC, when that is simply not the case.
Summary: DWC vs Coco-Coir
Coco-coir is often compared to DWC but it falls short in many categories. I would only recommend coco over DWC for those that cannot maintain reservoir temperatures for DWC (below 70F water temperature and below 80F ambient air temp). Even then I think it would be easier to set up a rDWC system that keeps the main water reservoir outside the grow box. Coco is also useful for organic nutrients, though no one I know can identify organically fed vs synthetically fed cannabis in a blind test.
To get the same convenience of DWC (being able to leave your plants unattended for 1-2 weeks at a time) you will need to set up a convoluted drip irrigation system as well as drain systems to collect excess runoff.
For the grow doctor DWC is the clear winner. You’d have to be coco to choose coir.
Resources:
http://www.fao.org/economic/futurefibres/fibres/coir/en/
https://www.cocoforcannabis.com/diy-automatic-watering-system/
