Echeverias in winter

Cold and very windy outside tonight and it has been a particularly long and cold winter. But against the odds Echeverias seem to survive very well. The photo above was taken a couple of days ago of Echeverias, Sempervivums and even an Aloe planted in a raised bed in the garden. Admittedly I usually keep a a sheet of plastic covering them in the worse weather. (Actually I use an old hamster cage lid - the hamsters long since having expired.)
I've kept the basic Echeverias (including 'peacockii') going in the garden for the past 12 years without any protection but these larger varieties such as Perle von Nurnberg (centre) I thought would be less hardy.
I'm going to grow more Echeverias!