I live in southern Sweden, where temperatures can get down to around 20C / 4F in the winter. Any tree grown outdoors is exposed to quite a lot of darkness and cold from around early November to late March. It's from this environment I've taken an acorn that have now grown indoors to a small oak tree for almost a year. The goal is to make a bonsai out of my baby oak, but I'm not sure if I should make it an indoor or outdoor bonsai.
My question is basically; Would an oak from a northern climate thrive if kept indoors through the winter, or should I leave it outside?