I haven't grown coral vine before but found a post on Gardenweb about wintering it over in Atlanta. That may be a little warmer than where you are though and yours might not be established enough to make it through the winter if you leave it in the ground. It's strange that it's gotten smaller. I would be curious what the roots look like. Perhaps part of the tuber has rotted. I think I would store it in the crawl space again since that worked and try different growing conditions next summer. You might be able to divide it and then try one in the ground and store the other in your crawl space. Sounds like a very pretty plant. Good luck.

Here is a link that might be useful: Do you grow this vine?

Thank you for the suggestion. I was starting to think of digging it again since that worked last year and I don't want to lose the plant. I'll be taking your suggestion. I think I'll pot it in really good potting soil and see if I can make it strong, and maybe see if I can propagate it from cuttings next year, then, indeed, I could try it in both places,out and in. That would be the best scenario. I am in a similar situation with a Dutchman's Pipe I brought from Houston area - no clue whether it is the hardy one or not as its been in a pot the whole time. I'd love to propagate that too. I have a really strong hunch it is tropical, though, and I'd love to have seeds or cuttings of the hardy kind, esp for the pipevine swallowtail. Going to keep that on my wishlist.