It does die down overwinter. It'll grow anywhere, but it is a native of damp spots, and does well in the shade, so that would be a good place to put it. I don't know whether the seed needs stratifying or not, but I'd tend to plant now (or plant half if you have plenty) and see what happens. Leave it in pots overwinter, somewhere it can get cold while still getting a bit of protection. I use a frame under a tree for my hardy perennial seeds.