My bonsai friends in Montana dig a hole about 6-8 inches deep large enough for the pot and set the pot in it and cover it with sawdust or straw basicaly filling in the hole. They leave the top of the tree exposed. Junipers will take this just fine. The main thing is to protect the roots from freezing. The roots can go down to -5 C without much risk. This tree should not be in the house ever for more than a few days. Junipers are out door plants an will die from lack of light and the dry environment inside of a house. Good luck, Jack