This is almost certainly as far north as one can push this plant (erratic zone 5, technically zone 6 but capable of zone 4 winters). However, my small clump is slowly increasing by about a stem or two a year. It comes up Extremely late, so marking its location is critical. The yellow background is Ozark primrose, a very happy and useful plant.
Acair Fearann 
I love this little woodland plant, and saw big stands of it in the shade at Chanticleer Garden. After two failed attempts to grow it myself I am on my third attempt with one plant. This one is the keeper this time, I hope!
I hope it survives; this one has made it through two winters now, and I think it might be a little bigger this year…
Spigelia is just a fabulous plant. I have large vigorous plants in two different parts of my garden. One gets alot less sun and actually blooms longer and later than the other.
Good to know! (my garden is essentially all shade of one type or another…)