Have you put the plants out yet Catwheazle? Into the open garden I mean? If not, perhaps that would be the best thing to do, into a cool, leafy, gritty soil. They shouldn't need a lot of feeding and the old leaves may well yellow but as they do so, new leaves should come from the centres of the plants. Don't despair just yet. Soldanellas can be tricky but I think they prefer an open garden to a pot. They are related to primulas of course and perhaps like the open spaces. (Though I know there have been some stunning potted specimens at AGS and SRGC shows.)