Hi John look exactly on your map: Nürnberg is a enclave of 8a.... same as frankfurt or stuttgart, Munich is 7.
But don´t forget that the climate in Bergen is not so dry so many exotic plants will not grow or have fruits... and at the costs strong winds can stop the growing.
It´s right that sometimes in southern germany -15°C can reached at night, but not in the cities...

Cheers good night, John.