Yes, we have palm trees in Sweden!
But they are kept indoors in heated greenhouses all winter.
In mid-June it is perfectly safe to plant them outdoors as seen here at the Gothenburg Garden Society.
For a few month, we enjoy the exotic plants.
Before the frost comes in the fall, they are taken indoors.
The method of having Mediterranean plants in a heated green houses for winter storage (often very elegant and fancy buildings) is an old practice used by gardeners in palaces gardens of Northern Europe.