My first year starting bonsai, winter care seemed the most intimidating aspect of keeping trees in Minnesota.
Unless you only keep tropicals, outdoor winter protection for your trees is a necessary part of caring for bonsai in Minnesota. My first year of bonsai I stored my tree with Lionel Flood (he offers this great service, firstname.lastname@example.org) for the winter, but I knew I had to build a cold frame if I wanted to expand my collection. I toured a lot of members cold frames at the member tour and got a lot of great tips from experienced members. I hope this article helps and you find that winter care isn’t scary or intimidating at all.
As the number of tropical trees that I have has grown, I have run out of south facing window space in my house so I use this greenhouse for some of my tropical trees during the winter. It is approximately 4 feet wide by 5 feet long by 7 feet high. It is tall enough for me to walk inside.