Neil,
I have just re-read this thread and would like to add to what I said in 2016! I read elsewhere that Lewisia rediviva etc do not mind the winter wet and cold - they just need summer drought during dormancy. Being fed up with aphids on the overwintering leaves - it's very difficult to remove them without damaging the leaves - and because I do not like to use pesticides - I left all my pots of Lewisia outside this past winter, where they have endured cold winds, frost, freeze-thaw..... and they are looking good, and fairly aphid-free, too. After flowering they will have a dry summer holiday in the greenhouse.
