I live in SW Washington state. I have a greenhouse, but I am trying to phase out all my tender plants. It's too expensive to heat the greenhouse, especially on those rare five-day cold spells down to 15F. There isn't enough light in the winter: too cloudy, sun too low in the sky at this latitude. I am a big fan of indoor growing under lights. A basement or laundry room is ideal for this. All of the waste heat from the fixtures goes into heating the house. So you have 100% energy efficiency. You don't have to go outside to get to the plants. Pest control is a problem; you have to restrict your use of pesticides in your living quarters. For tender plants that go dormant in winter, like Haemanthus, I grow them in the greenhouse in summer, and move the pots into the laundry room for the winter.