Sedum is a charming genus, with its typically soft, rounded leaves, hugely rewarding flowers to insect visitors and a willing, robustness to grow well regardless of constrains.
Ubiquitous as a ground cover for rockery's and now green roof's the genus “Sedum” extend in form and function way past these simple applications.
“ Ideally adapted, Sedum provide a multitude of advantages as part of green roof technologies, being crucial to a number of butterfly species just one.”
My favorite way to include species of Sedum is among naturalistic planting of grass meadow, creating different layers and levels among the sword.
A nice UK site for Sedum is https://sedumshack.co.uk/