[Cynthia, Prescott, AZ]

I'm not into S/H, so can't comment on it. However, a couple of comments.

I would make it a point to stop using vermiculite, and start using perlite as a substitute. I used to use vermiculite (50%) in my mix for the last 20 years. However, the current mineral for making vermiculite comes from Africa, instead of Utah, where infinitesmal amounts of asbestos were sometimes found. The stuff from Africa, or where ever it is coming from now, has proved deadly to my plants, and I think it is the very rapid break down that is the problem.

Most Dendrobiums, and almost always the ones from home centers and the like, should be allowed to get very dry in winter before watering when not in growth or bloom. If in doubt, add a few extra days dry. The leaf drop may be natural, and should not be considered a problem. If one of your Dens is doing fine, don't change anything for that plant, it probbaly has very different parents from the run of the mill Dens. All Dens while growing should be watered very liberally.

For the Paph, you could try more light, or, and this is the time of year for it, cool the plant down an extra 10 to 15 degrees for a few weeks.