Hi Linda,
Welcome aboard!
I for one would love to see a pic of your delicate Sedum hispanicum 'Purple Form' - I have 'Blue Carpet' and one that looks identical called hispanicum var. polypetalum. I agree they are delicate, and seem to do best with extremely sharp drainage. Even in perfect conditions they tend to have die back issues.
For soil, there is a lot of information here on the forums, but in general, extra large sand/small gravel added to the native soil provides the good drainage they need.
