My care habits seem to be death to S. hartmannii

[vmax3000]

I can't figure it out. I have tried mounted and potted...each time, death is the result. I have great luck with vandas, in general. The latest attempt with Sarcochilus hartmannii is a mounted plant. Around the base of the plant, there are scads of little plantlets, but the bottom leaves on the main plant have yellowed and fallen off. The leaves have developed sunken lines...kind of a dessicated look, but the humidity in my greenhouse is ~55-60%. I don't water S. hartmannii as much as I do the other vandas, as this one is surrounded with sphag. moss. It's up high in the greenhouse with the sun lovers. I am stumped. Should I just give up?