Right now the D. paradoxa are still in the plugs they were in from the seed tray, which looks like a mixture of >=60% peat to perlite. I planted the plugs intact into a mix of 2:1 sand : peat, which is the recommended mixture. I'll probably separate the individual plants into 2:1 sand : peat early spring, and take a look at the roots of the plants that fell apart on me. Or I just may leave that plug alone.
They seem to be doing well, the centers are getting greener every day with some new leaf growth with dew forming on the new leaves.