you can let them go dormantin a unheated GH. Most of the hedychium are go to zone 7. You can cut it back or leave it on until it freezes. I just keep them in the pot and reduce watering.

Thanks.
Karyn

I put my hedychiums just under a large high energy efficient light but I cut all the stalks down and just leave the small ones that are under 2 feet high - actually with any of my plants under lights I do this if the leaves get to large especially my brugs I just trim them back and let the smaller ones take over - in the spring around feb/march I will just let them grow out