20G terrarium plants
 

I'm planning to start up a terrarium - a tropical set-up, 20 gallon tank, mostly orchids but a few ferns and other plants. The problem is that some of the orchids really need a dry/cool period to flower, and others don't. I'm wondering if the warmer-growing orchids can tolerate a cooler and drier winter period (for instance, around 65-70F). Here are the orchids I'm considering:
Dendrobium aggregatum
Haraella odorata
Ludisia discolor
Mediocalcar decoratum
Phal. schilleriana, violacea, or other small phals
Paph delenatii
Bulbophyllum frostii x dentiferum

I'd really like a phal species and a paph/phrag species, but if the ones I've suggested aren't suitable and there are better ones, that would be great to know too.

Also, I've been having a hard time finding out sizes. If anyone knows that certain of these are too large, I'd be happy to know.

Unless you keep it trimmed, Ludisia will outgrow a 20 gallon. The rest sound fine, though I don't have as much experience keeping the phals/paphs. A couple other interesting miniatures to consider that have never given me problems would be Schoenorchis fragrans, any of the Restrepia, and some of the smaller vining Dendrobiums like lichenastrum. Small Bulbophyllums/Cirrhopetallums usually work out for me well, too.

another suggestion is Dendrobium laevifolium... itdoes it very well in a terrarium... also Aerangis and the smaller Angraecum (e.g. A didierii)... or Trichocentrum tigrinum, which is also good for terrarium, rather mini and with a large great flower

Phal violacea, and schilleriana (especially when in spike), seem to be a bit too big for a 20 gallon terrarium, I would try any of the Section Parishianae...