Hi. I'm in need of an urgent help if there is still any hope for my bonsai. I have a small chinese elm, currently living indoors over winter. It was living outdoors during the summer but I had to take it inside, as the climatic zone where I live it was down to -15C. Unfortunately I live in a flat where there is central heating everywhere and I could not put my bonsai in colder location.

Last month bonsai lost all its leaves but I kept it watered and hoped that it would recover. I have two trees and it had worked for second one as it bounced back. I was concerned about this one because it looks like it's dying. I have read online that to check if tree is still alive, I have to look for green layer under bark if I scratch the tree. I have done the test but I can't see the green! There is only one area at the bottom of the trunk where there is a little green ( see picture). Is there a chance it is still alive and may be saved? If so, how? Please help!

Chinese elm is a decidious tree that in my conditions shed all their leaves in spring when heat comes back. It makes me believe that it was what happened when you brought it indoors. In that case you will see buds sprouting in 2-3 weeks.

I have no recommendation about how to make it come out healthy in spring. My elms see temperatures below minus 15 every year and are healthy every spring. Next time, don't panic. It is a very hardy species. And don't scratch bark. It hurts the tree and just gives you a clue about something that will be obvious in a few months anyway.

Thanks, so you think best bet is just wait to see in a few months if it has died or its going to come back..
I thought the way of telling is common to use, whether it is alive still or not.

I was thinking of repotting it but it may hurt it even more.

Absolutely DO NOT REPOT that will only make it even less likely to survive!!!