Thanks for writing. Most sun-loving perennials should do all right as long as they get afternoon sun; I know I have success in my Iowa garden with plants like baptisia, amsonia, salvia, peonies, etc. in half-day sun.
If the sun-lovers are not performing the way you'd like them to, you may need to do some trial and error to find out what does best in your particular set of conditions.
---Justin, Senior Garden Editor, BHG.com