Hm, I have curcumas, and all the hedychiums that die back once it's down int o the 30's for a few nights, and the little Peacock gingers - Kaemferia - are total divas and dive underground every winter, although they did reappear quite early this year. The alpinias seem to keep their leaves through thick and thin, as do the costus (spiral gingers). I just got a start of a blue ginger - dichorisandra? - so I don't know how tender it will be. The Pinecone gingers - zingiber zerumbet - die back to the ground every winter, too. They were spectacular this year with all the rain we had.
My yard is quite protected for winter, but we are at least a mile inland from the water, so I have nights every winter where I do cover things like my veggies to keep them from going dormant. Last winter only a couple of nights went below 40.
