^ good advice there.
Silene capensis/undulata seedlings seem to be quite vulnerable to damping off. In that sense, similar to syrian rue in the first stage. Water from below without excess, and if they seem to weaken, avoid saturated humidity in the ambient and support them packing gently a little soil in the base of the germinal stem to keep them straight.
Watering from below and not too generously also stimulates root growth which will toughen up the seedling.
Mandrake
PS. An observation... "xhosa" is the name of a whole ethnic group in southern Africa. Sometimes S.Capensis is called "Xhosa dream herb", because it is the most known species in the (large) list of the ubulawu shamanic tradition followed by the Xhosa, but in a way calling S. Capensis "Xhosa" would be a little like calling Banisteriopsis Caapi, for instance, "Shipibo".