I don't have direct experience but it is good not to overwater the container during the winter. I wonder if it will pass into dormancy if you cut down watering and feeding it during winter?

Yeah. I was thinking the same thing.

I was going to suggest same as Joseph. I never overwintered that one but most of the tropicals I bring in I let go dormant in my cool cellar. I am trying red mandevilla this year. You can also root cuttings just in case and try to grow them in a sunny window or under lights.

Here in South Georgia, I over winter it right where it is. The cold kills it back but come spring there it is again, the first thing to sprout out. I have had mine now about 5 years and it has always bloomed heavily each year as long as I give it lots of water. I was told once to give it an inch a week. I have mine in a 12x12x12 container with about 2 inches below the container top. I fill it with water at least once a week and a lot of weeks I fill it twice and it blooms its little heart out. It is also very easy to root.
To bring it inside i would not water it hardly at all. Just my two cents worth.

Thank you for all the advice. I am trying to root some now as well. Maybe one way or another I will have one survive.
Denise