Hi
Remember that it`s very windy and wet on Shetlands and parts of skotland.
In these plases cordeline are growing , if they can lots of other things can.
The west coast of Irland are also very windy and wet , but cordeline are growing there. And remember that Sun and hard frost can be devestating.
A bloke of mine lived once in Munchen, and told me that snow and frost are much more sure there than here
John