Hi,
I'm not an expert but from everything I've read and watched, providing a moist environment encourages root growth. I would stay away from bark until you at least have a few roots. I've had good luck with setting rootless orchids on top of constant damp sphagnum moss in a jar or vase for a few weeks. There's tons of youtube videos using this strategy to encourage new root growth and I found it very effective. Miss Orchid Girl has a bunch of videos of orchids in "ICU" where you can also see the stages of root growth. Hope that helps and good luck! ps. very jealous because I've been on the hunt for Saint Andre for several months now.
