I know that the phlox, scabious and poppies like a thin, poor soil and a lot of sunlight.
The ranunculus i think needs a more moist soil.
I have them all and those are the positions i give mine and they thrive.

They prefer neutral to slightly alkaline soil in my experience. but thats my soil and they do well for me.

My Phlox take some shade, Louise. I have some in sun, and others facing east. They all thrive. My soil is neutral, and well - nourished. I grow Oriental poppies and scabious too, but in sun. Strange, isn't it!

Thank you all I believe our soil errs to the acid side I grow azaleas heathers etc well and most other flowers except those mentioned