I got a phal at my local OS about 6 mo ago. I live in the San Fernando
Valley (Los Angeles, only hotter). Everything was stable, even sprouted a
new and hefty root. I mounted it and moved it to my patio where it gets
bright shade for long periods. Been pretty hot here lately 100F to 105F by
2pm. The other day I noticed that the lowest of 4 tiers of leaves had
turned brown and withered. I figured, well, ok I read that some Orchids are
desiduous. No worries, but now only about 5 days later the next tier (2
leaves) are doing the same. As a precaution I moved it back inside.
Everything else seems healthy, the roots and the other leaves have good
color and feel. So is this normal desiduous behavior or is it just too
blinkin hot. I mist the moss daily in the am, sometimes twice. BTW there
are 4 other mounted orchids of various types on the patio in a group, seem
to be fine.

Got $.02 for me?

Jack