If you are not opposed to a systemic insecticide control, I use Bayer 3 n1 Insect and Mite Control available on Amazon.

I used an insecticidal soap that was marketed as organic from one of the local hardware stores. In reading up on mites, the references I found said products that worked by suffocation tended to be more effective. Because of the short generation time of the mites, they rapidly develop immunity to miticides so if one does go this route more than one formulation may be required.

I sprayed mine down weekly (thoroughly drenching the top and turning it upside down to coat the bottom). I think it took 6 or 7 applications to get rid of the mites. I could see how this might not be doable in a large collection. The soap also caused brown spotting on the flowers, but getting rid of the mites was my priority.

I saw a few mites several weeks after I stopped treatment, but I'm not sure if they were tied to the original infestation. In the mean time, my Dendrobium had also become home to various predatory mites, thrips, and other insects that occupy my yard and I've seen no signs of spider mites for several months now.

UPDATE: I bought an inexpensive mini-microscope and found the little beasties!

Please help ID - I think they are false spidermites?

I tried spraying a mixture of water/mineral oil/drop of soap several times. But they persist! :((

I'm thinking about the Bayer 3 in 1... Thoughts?

I have about 100 plants - so I'm kinda freaking out about treating them all... :(

I think you're right on the ID. I haven't found any success stories with homemade sprays on spider mites (not that there aren't any). Maybe try the Bayer and follow up with an insecticidal soap if any mites survive?

The brand I used was: Garden Safe 24-fl oz Insecticidal Soap Insect Killer. There were no mites alive after treatment until more eggs hatched (6 or 7 days after treatment). I only had one infected plant and two that were in close proximity so I went over them regularly with a magnifying glass to check.