I recently developed an interest (which was amplified to an obsession by the quarantine) for carnivorous plants. There are keen growers out there and one of the topics in those circles is the substrate. Most carnivorous plants require a nutrient free, acidic medium. I was immediately tempted to try out coco! Obviously people have tried that before and a lot have failed, but with the knowledge on this forum, I should be ready to try it out, but I realised I lack some understanding. Most CP growers use Peat Moss and Perlite in different ratios, with the occasional addition of sphagnum moss, sand, bark, lava, pumice, etc.
1. The way I understand it, when buffering the coco with calmag, we are replacing some alkali-ions in the coco (such as Na and K) with Ca and Mg. If I am then watering my carnivorous plant with RO water, is there a chance of mobilising these ions again? Or only if I introduce other salts?
2. What is the pH of coco on its own? I know we want to keep watering it at slightly acidic pH, but why?
Any more advice on these issues would be very much appreciated as I would love to avoid peat and move to a more sustainable medium such as coco!
Coco coir has a neutral pH range of 5.2–6.8, but this range will fluctuate over time. Peat Moss has an acidic pH, generally in the range of 4.4.
The default "CP mix" that works for the majority of carnivorous plants is an equal mix of Sphagnum peat and coarse sand. Perlite is a good alternative to sand but it has drawbacks. In some areas it is hard to find perlite that is not salty.
Using distilled water will strip away nutrients making the substrate inert. The reason we buffer is to prevent future problems with calcium and magnesium deficiencies. You won't need to buffer if you just want an inert medium. Coir will likely have salts and should be rinsed thoroughly as well.
The general consensus among cp growers is to just leave coco coir alone when it comes to growing carnivores. Peat is readily available and inexpensive and most go with that. But that doesn't mean it wouldn't be interesting to experiment with the stuff to see what results come. Happy growing!!