British Columbia: Suggestions for over-wintering Hedychium gardnerianum?

I've been nursing Hedychium gardnerianum along for 3 to 4 years and had blooms for the first time this September. I had Hedychium 15 years ago for a few years - they bloomed if they wintered indoors and gradually disappeared when I left them in a south facing area that was too dry. I left this batch outside in a west-facing fenced site one winter and they languished the next year. After they were dug and over-wintered in a 10°c garage they took all summer to get growing again and stayed spindly. Last winter they lived in the house, not cut down but apparently dormant, in pots in a sunny south window. They've spent the growing season in-ground in a south-east alcove, backed with a stone wall a couple of feet away. With weeper hoses and fertilization from time to time there's been good expansion of the rhizomes this year and 3 blooms, the last struggling to open over the past 2 weeks.
I'd rather they stayed outside in-ground this winter, but I don't want to lose them. Ag.Canada's postal code mapping puts me in zone 8b. How best to manage them? Last February seemed unusually cold for quite a while here.
Also, I've heard that the rhizome size is key to flowering. Can anyone comment on that? These have taken such a long time to bloom; I bought them commercially in 1 gallon pots, so they were probably quite small.

 

I apologize for apparently hijacking this thread to comment on the climate zone, with the result that there have been no replies to the questions asked and a lot of comments on climate zones. The entire discussion is now at Plant hardiness zones Canada / USA, which was an existing thread that received no replies. Please discuss climate zones in that thread, and over-wintering Hedychium plants here.

 

It's been helpful!
I found older references to Hedychium in the Tropicals section and have messaged those gardeners directly to see how their methods have worked out. It's looks as if it would be wisest to bring them in again.

 

I am glad to see that you are getting information, though we don't get to see what you have learned, which is part of the benefit of a public forum.

 

There you go. That … is what's important.

What works for one, may not work for someone else in the same zone. Zones don't tell the whole story, local gardening does.
Cheers.