If the leaves have all dropped off, I dont water mine at all, unless the p-bulbs shrivel up a lot. Then I give a quick splash of water and it fattens right up. Then, in spring, a new growth will begin. Do not begin watering until the roots from the new growth are a few inches long. I personally dont take my catasetum types out of their pots, nor do I cut off the old roots. Some ppl do, though, and it just a matter of preference. Heres the AOS link for these guys:
http://orchidweb.org/aos/orchids/doc...ecatasetum.pdf