Jay

Hi Jason, I know we have not seen any suggestions from the more knowledgeable, so I will give you what I know. I remind you that I have overwintered chinese elms for two years and have some knowledge for a novice.

You say you need to overwinter on your balcony. Here is what I suggest. You are looking to protect the trees from the wind. during winter they can dry out quickly with the winds, now I'm talking about the tree not the roots and soil. If you can get a box, styrofoam or just plan wood will do. Make sure there are some drainage wholes so any water will not stand. Place some mulch at the bottom of the box, then put the tree or trees if the box if it is big enough. mulch all around the tree up to a little over the soil line. Cover the box, but not tight. Light is not an issue during winter but some is good. if it snows fill the box with snow, it will insulate the tree and also water it as it melts...remember the holes in the bottom of the box. keep the box up against the slider glass door or uyp against the building. There will be some heat leakage, there always is. The heat will moderate the freezing temps.

Now if you have a friend that has an unheated garage, that would be better, still do the box and mulch .. add the snow also but the garage will moderate the temps and help somewhat. You are in a slightly colder climate than I (5b/6a) but should be able to get away with this type of protection.

Good Luck..
Jay

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A Bonsai student living with his trees at N 44.37 W 77.49...
Think before you act... then think again... no good comes from rushing