Had you thought about sarcococca (sweet box) - what the flowers lack in size they make up for in fragrance. Very shade, drought tolerant. Larger, clethra acuminata but it's going to want summer water. Hydrangea relative Dichroa will bloom in, or at least tolerates less sun than hydrangea, but I'm trying that one for the first time this year and I do have a morning sun site for it.

In this mild maritime climate, I have pieris in full sun with no damage, I have trouble seeing it do well in full shade. Do you provide summer water at all to the area you are talking about? Drought in summer is one reason for reduction of flower buds on azalea. Or, had you thought about removing a few limbs from trees, or opening up shrubs to provide dappled rather than dense shade?

Thank you, morz8. I actually have some sarcococca I need to move to less sun because THEY are not doing well. I was planning to try them somewhere else, but you've inspired me to try at least one here.

I think you're right-- the azaleas would like more water. I have others that bloom well with minimal supplemental water, but they've been here for years before I moved in, so perhaps are just so well established, and/or these others have some more root competition or some other factor that I'm not taking into account.

I may conduct an experiment and try both approaches!

kerria japonica