Overwintering cordyline cabbage palm

I have seven gorgeous cordyline cabbage palms (or burgundy dracaena spikes) in my railing planters on my balcony railings. They've really grown to be gorgeous and I hate to let them freeze this year. Most of my plants are annuals and I just have to let them go since I have no way to overwinter them. But since these were dessert plants originally (I think) I was wondering if I could save them somehow. My mom used to save her geraniums in the crawl space every winter, so I was thinking I could do something like that in a space high up in the garage that does have dim light all the time and stays above freezing all winter long (unless someone leaves a door open, which shouldn't happen). Does anyone have any thoughts? Should I pot them or wrap the roots? Any thoughts would be appreciated including telling me it won't work if you know it won't. Thanks in advance. Tom.

tom - I bought mine about 4 years ago as my first hobby gh plant. It goes outdoors in the summer and comes indoors once the night time temps hit about 40. Since I keep mine in a pot, it's easy enough to bring indoors. You could transplant yours into pots and bring them in. If you have a sunny window in the house, you could put them there. I generally treat them as "floor" plants on saucers rather than trying to find table space for them. They transplant rather easily. Not sure how cold a temp they could take or if you'd need to cut them back if you have a garage space in mind. I think I'm too chicken to try letting them go dormant.