It's not necessary or necessarily beneficial to keep Den. nobile completely dry in the wintertime; check out the
Bakers' culture sheet for winter rainfall averages near Chiang Mai, Thailand. I keep mine much drier in winter than I do in the summer because they're not actively growing, but I still water every 4-6 days and sometimes more. Can you put your plants where they'll get some water, but not as much as other things that want to stay moist throughout?