It's been a long time since I've asked for help with some chids. I attended the Martin County Orchid Society show this past weekend and purchased two plants from my dear friend Alexis of Tropical Orchids. I wasn't going to buy anything but thought I give these two guys a shot.... so I want some input as to caring for them. They are: Oncidium ampliatum x sib (Turtle Orchid) and Enc Randii x sib. I was told the Enc Randii needs lots of sun but want to know about water and temps and any other helpful hints so I don't kill them next week....
I purchased Onc. ampliatum from H. & R in a four inch pot about five years ago and it is still in the four inch pot sitting in a larger pot. Roots have covered both pots and still growing. Your plant will be happy in very bright light (cattleya light), allowed to dry out well between watering and regular weekly or bi-weekly applications of fertilizer. Basically, it can be grown well the same way you grow a cattleya. Too much water and you are inviting rot. So make sure it dries out well. This plant also grows very well on a plaque.
From what I've read, randii may be okay with light a bit lower than that of a catt. Very nice flower on that one -- I look forward to seeing it in bloom!