Does anyone know whether columbines prefer acidic soil or neutral? I have
them do OK for a short while in acidic soil but then they seem to just
disappear.

Same thing with astilbes. I think I am getting something important wrong
here. I know for nasturtiums and lavendar I bring in sand and put them in
mostly sandy soil and they do fine. I haven't been able to locate a
resource to tell me about astilbe and columbine, though.