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I've found that almost all phrags are in moss with hard rock below. They are almost always in full sun at that altitude. Lower, they are in mid-day shade. They like damp to wet roots and a dry plant in daylight and a wet plant at night. I've started some experiments for growing seeds of all types in a natural way, using moss and lichens. I have found longifolium growing in trees that are moss-covered.
I was think of my own growing conditions when I made that comment. In that regard, you are very lucky!
I have phrags hanging in basket culture doing good Dot. That's 3/4 of the way to mounted. If I can do it, I don't see any reason why you can't.
How often do you water them???
I through water on them every day, some days more than others,...