Saw your post about C. cyprium, which I have been growing from seed from the seedex. I have found them very easy, to be honest. I have them in my unheated garden house, kept medium moist and with late sun. Low temps are about -6°C, maybe colder last Winter. I have at least 4 different selections from the seedex and, interstingly, one of the packs did little germination and, yes, the seedlings damped off. Maybe we have this in common. Otherwise, this species has surprised me, as I didn't expect the hardiness. At this point, the only species I cannot seem to grow in the garden house is C. rolfsianum. Even C. africanum is doing well, although i di keep it inside for the first Winter, not wanting to trust the few seedlings I had to -11°C the first Winter.
Maybe some of the seed carried a pathogen, or more likely, had a different providence.
cheers,
Jamie