My new phaius is in spagnum only and it's got tons of new plantlets. First time i've seen one in spag and it's the healthiest one i've ever seen. My other, I mixed a bunch of "junk" stuff. I took potting stuff from other plants i'd repotted, some peat moss, very large bark chunks and a few leaves and twigs i'd clipped from around the yard and mixed it all together. That plant took awhile but it's finally beginning to take off...even giving me a spike this year. They like alot more fertilizer than normal plants. When I have a bucket of my fish emulsion fertilizer and other fertilizers mixed, and have alot left over I dump it on my ground orchids.
Good Luck....these are highly rewarding orchids to grow. Even without flowers they are so pretty.