Thanks for the various suggestions about planting tuberosus. I asked
the local supplier whether they expected this plant to be planted
outside in Ottawa (zone 4B) and they said that it could either be
planted inside or outside. if planted outside, it should be protected
with 6 inches of dead leaves or straw. They imported it from the
Netherlands with the Dutch suppliers being fully knowledgeable about the
temperature regime in this part of N.Am. They said that they ordered it
because of "popular demand", which surprised me as I did not think that
we had a large Hemodactylus demand, or any demand it this area.
As to Mark's question about Florida. I believe that the temperatures
are very similar to its native region but that the humidity would be
very damaging. It might survive in very well drained soil and
protection from the rain during the summer.