yeah, astilbe gets listed as a shade plant a lot, and it won't
die there, but it really wants quite a bit of sun to look like the pictures. Maybe if you live in the south where it gets super hot in the summer it needs more shade? Not so much here.
If you like it but want more flowers, I might move the astilbe to the new spot - that sounds like a pretty ideal amount of sun.
Or, how about
That does pretty well for me in sun or shade - though the sun will again have more flowers
or
I just started growing this last year in a fairly shady spot and was wowed this spring by how big and dense it was. Photos really don't do the flowers justice - they are really dark and stand out at a distance.
Is one of my best flowers for shade. I don't have that exact cultivar, but I was having a hard time finding a picture with the whole plant in it. Flowers in the fall, which is cool.
oh, and heuchera's can do well in shade. Again, not much in the way of flowers there, but the leaves often have patterns.
and of course ferns and hostas. Those are actually meant for shade, unlike astilbes.
