What soil and how deep should Crinum powelli bulbs be planted?

The bulbs should be planted with the neck just above soil level. All the information I've been able to find suggests that these aren't too fussy about soil, so a decent potting compost should be fine. The only other hint is that these grow best if the roots are restricted, so don't make the pots too big. I haven't grown these myself, but having looked at photographs, I think I may give them a go, too!

I planted 2 of these in pots on Monday. I used multi-purpose compost with a bit of perlite and Osmocote.

I don't know what temperatures they can tolerate though.