Oncidium back bulbs

[Bribri]

Hi all,

I have oncidium back bulbs and was hoping to get some new growths from it. As in the picture, I replanted it in a bark and sphagnum mix. Roots are healthy but the bulbs seem a bit dark green fading into light green yellow-brown color. Is that a normal color for bulbs? As I am reading through threads, should I have this in a sphag bag or is my set up acceptable? If I do sphag in a bag, would the dampness cause rot?