I have 3 Chinese Elms, 1 Seiju, 2 Hokkaido. Last winter I kept them in my unheated garage. They all took some damage, I assume from freezing,. The Seiju recovered well, as did 1 of the Hokkaidos. But neither outgrew where they were the previous summer/fall. The other Hokkaido survived, but has been slow in recovering this season.
I live in Southern Ontario, zone 5a/b. Should I keep these Elms in warmer conditions for the winter? I have shelves with led grow lights in the basement, but the average temp is 70-72.
Thanks for any advice.