|I live in zone 3 - or northern zone 4 - not quite sure. I have a Christmas cactus that is 20 years old. I once hung this outside on the north side of the house during the summer when I lived in the Milwaukee area (slightly warmer winters). I would like to know if I can hang it outside in this zone, should it be in the sun or shade, what is the coldest night temperature it can tollerate? I have a corner I would like to hang it from that is partial shade, some sun, on the south side of the house. It now sets on a table in front of a south window, and is blooming right now (Memorial Day). Please advise. I don't want to kill it!