Yes, you could do it. I've been pushing tropical species in my zone 9a/8b garden and growing them successfully. You just need to seek out microclimates and avoid putting them in open areas where the cold of space is going to nail them. If you have a south wall, put them in buckets right up against it. I grow a key lime tree that way, even though they would die a few feet out from the wall. Think about thermal mass. Water holds a lot of saved heat energy, as do buildings. Experiment! Plant them in a half-dozen places! Mulch, put rocks around them, etc.

Here's a little encouragement along those lines:

http://www.floridasurvivalgardening.c...