Hi.
Chinese elm is one of my favorite species for doing bonsai for the time being. I live in south of Norway and have a question how you store the chinese elm in the winter time when frost. Where I live the temperature can get below -10C degrees for a week or so. I had two trees that lived through a couple of winters outside on the ground, under a bench covered with leaves. This year they died. Probably due to rain combined with hard frost. Is there any one that have advice to share how to protect them? It would be most welcome.
Can they withstand -10 ??

In principle, yeah, they can withstand it. I think however that the problem might be with late frost spells, where the tree has started to wake up. This spring I also lost a chinese elm that I have had outside for the last 5 years, living through much colder than -10. Waking up fine and a frost wave in April caused my lots of headaches this year..

I can confirm. Lost an elm as well in West Sweden (close to norway) due to late frost. From what I can understand there are many elms lost in Europe this year.

The coldest period my tree had experienced was 6 weeks below minus 10 day and night without problem. But onse they have budded they are sensitive and needs protection from frost.