I recently purchased an Oncidium about a month ago and it has steadily lost a leaf a week since i have gotten it. When I purchased it, it was in full bloom with no yellowing right now i have it in a greenhouse at about 80% RH at 80-85F during the day and it drops to about 65 at night. The bulbs have been shriveled up since the time of Purchase and there are no new signs of growth. Can anyone help with this problem. I also fertilize weak weekly and water once a week.
In general, oncidiums don't like to dry out completely for more than a few hours. I have some mounted and some potted, and they all get watered daily. Even if they're already wet the additional watering flushes the media and brings fresh air to the roots. They seem to like it.