advice on seedlings Austrocactus, Pediocactus and Sclerocactus

[bvdg]

Hi everyone,

Recently I have been modestly successful in germinating small batches of Pediocactus, Austrocactus and Sclerocactus, not the easiest of species. Seedlings have in common a very large stem connecting root with base plant, as shown on the pictures attached. Most of them seem still in good shape, such as the first picture of an Austrocactus sp., and the second three recently germinated Sc Papyrycathus forming their first spines. I was wondering for next year how to repot these plants in the best way? Does the large stem for instance better remain above surface to avoid local rot?

Also, the third picture shows an Austrocactus seedling that is seemingly shriveling around the stem, although it still has an early root. It doesn't seem to pick up any of the moist remaining in the soil. I'm afraid this one will die off if don't do anything in specific. What would be your recommendation, or is it a lost cause?

I intend to grow them on their own roots, especially the Austrocactus sp. So for now, grafting is not considered.

Thanks a lot for your feedback!
Bart