That depends like always on your conditions.
I got it in a shallow pot in sphagnum from the nurseries but you also could use bark if you water more frequently.
I mounted it on a treefern totem and water nearly every day.
what's the best medium for bulbo lobbii types? i just got into growing them.
Most of my Bulbos including lobbii types are grown in plastic pots with New Zealand sphagnum moss as the media. I find that they grow best in a damp media under shady conditions.