Perhaps plants that are deprived of water in Autumn and allowed to dry out , might withstand the cold better ?
It would be an interesting experiment to do - select a group of identical plants and keep half dry and half fully watered . Expose them to similar cold conditions and observe the result.

Superb pictures
Has anybody estimated how old some of the plants are ? I`m thinking of the large Copiapoa clumps . If I had to guess , I would say 200 - 300 years old . Is there any way of proving this . Counting the growth rings is possible in trees , but in cacti ?

I could post a photo of my greenhouse at the moment , but it would be pointless as it is empty - all the plants are now in the conservatory . Saves me having to heat the greenhouse . I have a few items such as Echinocereus which might survive a cold spell , but having looked after them for several y...