I also find that unglazed terracotta pots work very well. A 4-inch to 6-inch diameter pot would do. these wick excess moisture away from the medium. I repot nearly all my Phals into these, with bark as a medium, as soon as I get them home. I do have a couple Phals growing in plastic net pots; if you have a hydroponics store nearby, net pots are usually very inexpensive.