I grow a lot of my Phals outside. Most have to come in when nighttime lows dip into the low 40s (Fahrenheit), but 3 have tolerated temperatures into the upper 30s and spent the winter outside only being brought in when there was a frost potential. They do things a lot slower, but because they’re slow the spikes last forever. One has been in bloom since March, one is sending up double spikes now which look to have a lot of buds, the third had some husbandry hiccups unrelated to temperature and is putting out a keiki. I think if acclimated Phals can tolerate quite a bit.
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