If you're following my thread in the Introduce Yourself forums, you know I'm in the process of trying to get two (of my four) Phals to rebloom. Some great advice was given that I need to obtain a big enough temperature difference to encourage new spike growths. Having recently examined my Christmas cactuses that are in full bud in our FL room (which is like a room that the previous owner created from a garage that has no air or heat), I figured why not putting the orchids out with them during the night and bringing them back inside during the day. I remember my grandma always told me Christmas cactuses need that temperature difference too, so I figured why not try it. Last night was the first time I tried, and this morning when I went to move the two orchids back into the house, I noticed their pots had all this white and grey chalk like substance on them. They didn't have that when I took them out there last night. They are both potted in clay pots, would that have something to do with it? The orchids themselves look unharmed, but the pots were a bit alarmingly. I wiped the chalky substance away, but now I'm wondering if I should continue to put the orchids in that room. As always, any info you can provide is greatly appreciated!