I am a graduate student and to earn my keep I help run a tissue culture lab. A student took home a petri dish of orchids and emailed me this question. I don't know the answer and would appreciate any information that someone may be able to share. Question: my petri dishes with the orchids and ferns were doin great and then all of a sudden one day the orchids all turned white except for a couple. i dont know y. thers some moisture inside the dishes and they were looking great and then bam white. i had them in a window that had some non direct sun-could they have not been getting enough sunlight? could they have ran out of sugar and starved? or not enough light? for a while i had them under a plant light could i have bleached them or maybe it was a bad light so it really wasnt giving them any help with photosynthesis? Thanks for the help.