Hi Fran ! I haven't experimented with either method (semi-hydro and FWC). Ray certainly has developed his semi-hydroponics technique very well.
As for FWC, I never delved into that side of things - as I was seriously thinking about factors like the awkwardness in needing to prop up a plant in a glass jar, with the leaves poking out the sides. But also considered how easy (or hard) it really is to keep good growth processes under control - preventing algae, preventing disease, preventing issues.
The technique I've been using is the classical one - a suitable airy growing media. I go for inorganic (eg. scoria).
Scoria is available in large quantities in my local region, and works excellently. Not just works, but works excellently. For me - has never failed. Convenient too. But all this depends on how many plants we have - maybe - for watering. On the other hand, it is certainly possible to automate the watering process (but still watch the orchids like a hawk) using timer systems.
I recently posted something about what I do at this following link:
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I grow pretty much all my orchids this way (except for catasetum, as I'm only beginning to test growing it in 100% scoria). My paphs, phrags, oncidium, catts, vanda, psychopsis, encyclia, angraecum, dendrobium, and my first ever phal ----- all grow in 100% scoria. Some of these orchids are my absolute favourite ones. Actually - they're all my favourites. But I have some more favourite than others haha.
One important thing to mention is that my seedlings orchids (still relatively small size) are grown in relatively small size bark pieces - suitably sized orchiata bark. Enough people said this sort of bark is good to use for orchids, so I just used that for tiny plants, until they grow large enough to grow in other media.
Some people even very successfully grow orchids in regular rocks, or even pebbles.
Anything that works nicely and conveniently and indefinitely - is great.
This isn't to say that people can't experiment and try FWC. It's really just about thinking in advance what sort of challenges we face with it, while considering there are super-effective growing techniques available - involving classical growing media. For example, a good-drainage plastic pot with suitable airy growing media (eg. scoria) - simple and effective.
While for FWC - dealing with the task of setting up the system for each plant, and then making the plant grow new roots that take to the water environment, treating or eliminating algae growth, ensuring water doesn't run too low on O2, maybe needing to handle the pot and do things with it every so often, etc.
Now - if a grower doesn't mind the technique they're using, and they're happy with the results - then that's one good thing. Very importantly - as long as the orchids remain healthy for years and years and years, then that will be best.
The attached image shows what can conveniently and easily be done with classical growing methods. The image is showing one of my catt orchids on the left - having two nice sized sheaths developing (with one sheath hidden behind another leaf) - this orchid growing really well in scoria. It is called Rlc. Brunswick Gem 'Coral' - produces nice reddish pink flowers. And the tall hybrid on the right is a recently acquired one - potted in scoria - a Ctt. Porcia 'Cannizarro' - produces quite long stems. It is like a mini tree heheheh.
Finally - since I was mentioning a lot about scoria, and that I use it ----- I can finish off with examples of plants growing in scoria - unmoved - for a few decades - in pots of scoria. The scoria unchanged, and pots unmoved, and plants untouched - for
few decades - watered automatically each night by pop-up rotary lawn grass sprinklers.
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