Recommend by Piet Oudolf et al for it's four season speak. The bright staple of a shade garden. Blooms for months and then the seedheads persist until you cut them down in the spring. Of all the astilbe types, this is my personal favorite.
Haven't bought from them yet, but the plant is solid in damp clay and almost complete shade. Offers so much when you have limited options.
Garden from the comfort of your home!