First: I will try to collect seeds. It's the first time I grow this plants. Usually I have no problems to collect seeds, but if the weather is bad (moist), I might not be able to collect seeds. Anyway I made a note of it and if I can collect seeds, I will contact you.
I winter sowed the seeds in my zone 6. They really grow very very slow in the beginning and the seedlings are so tiny. You'll need a lot of patience, haha.
I also might have seeds of Sedum sempervivoides, another special one. Same story about seedlings and collecting. Let me know if you would like seeds of those too, if I can collect them.
If you can send me some seeds of Jovivarba, Sedum or Rosularia I don't already have, you would make me very happy. They must be hardy to zone 6.