Wet climates produce many more species and numbers of epiphytes. BRBR

There is one more condition you forgot to mention; it has to be warm enough.
Few of the higher plants thrive as epiphytes where it consistently goes much
below freezing. Even in the Pacific Northwest rain forest, there are no higher
plant epiphytes (that I know of), because they are in Zone 8. The northernmost
epiphytic orchid in the Western Hemisphere, Epidendrum conopseum, is found as
far north as South Carolina.
Iris,
Central NY, Zone 5a, Sunset Zone 40
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