Check what they do in northern USA. I feel that there they get winters similar to Sweden. I am not sure what type of winters you get exaclt but I am assuming deep frost and snow for months? Maybe mulched and covered in snow? Just tossing it in the air, not knowing!
Thanks for the thoughts. When I investigate plants to go into my garden, sometimes zone information is missing for Sweden and I try to use north America as an indicator. For plants that are not sensitive to too little sun and like it wet it could be used as a guide.
What normally kill trees where I live are the excess water october to april and occational strong sun in early spring mars and april if the ground is still frosen. Despite the excess water during the winter the trees dies from thirst
I live close to the ocean. Here is not much snow to cover the plants.
My main challenge is to keep the trees fairly dry. For that the unheated greenhouse might be the best option.....If not the trees can suffer from lack of sun. In that case my basement with addition Lights is The best.
Br
Magnus