Evan,
I have grown this plant in my full shade garden for several years. It has never come CLOSE to 36" tall. I updated the ATP plant file to indicate 12-24" tall and wide, but really, I think mine never gets much taller/wider than 18". It is sited on the north side of my house which gets SOME additional water during really hot dry spells, and is in friable, humusy soil.
