Yes Marco, Many have luck wintering Basjoo's in 6,5 and even colder regions. You can chop em to the ground and mulch them but you will never see a flower. If you use the cage method and save a few feet of trunk they should flower and get taller faster. About 16' is max on a Basjoo but I'm sure someone has grown them taller. The leaf size you described sounds about right but they can get bigger. If you look in my gallery, the pic of the man standing by the canna's with nana's in the background, those are 16' Basjoo's here in 6. As far as being the tallest hardy nana for z6, Yes and no. It will probably winter the easiest but their are other varieties that may get taller such as the Orinoco but really need a lot of protection and may or may not live. Musella Lasiocarpa should survive w/ ease but is small. Velutina will live but only gets 9-10' +or-. Sikkimensis is next on the list for hardy candidate for your area but it is still being tested. I believe Itinerans is also being tested but I don't know the results. So all in all I think Basjoo is the best bet for hardiness/size in your area. Hope this helps. --Nate
