Answer: Cistus, or rock rose, are quite susceptible to root rot if the soil does not drain quickly. They are drought tolerant so very little water is needed, even in summer. If your plants are developing, or have developed root rot, you may not be able to save them - but I think it's worth a try. Dig the plants and clip away any dead or rotting roots; amend the soil with gravel or sand to facilitate fast drainage, then replant. You'll know in spring whether or not you were successful. If the plants do die off, you can replace them; the amended soil should provide the quick drainage they require.
Best wishes with your cistus!
Q&A Library Searching Tips