This is blooming its heads off this year. It's supposed to be fragrant (sold to me as the Chadds Ford cultivar), but I just get a faint smell that's not particularly pleasant. Maybe a little vanilla-y. Maybe on a warmer day it would smell better, or maybe, like some orchids, it smells more at different times of the day.

This is hardy to zone 3 according to Plant Delights. I have it on the edge of the bog in normal soil.
DH picked a couple of stems so you can see the "spiral" effect, here with a couple of tired hosta leaves.
Here's a nice article I found about the plant:
http://www.sunfarm.com/picks/spiranthes ... 4020.phtml