I do not have a greenhouse and I live in US growing Zone 4 so cannot grow begonias outdoors except in Summer. But slowly, part of my family room off the kitchen is doing quite well in playing the greenhouse part.
Most of my begonias are up against a window that faces 118 degrees SE. Though we get sunlight in winter, especially in the morning, pretty soon the huge maple trees outside will reduce that light. I have T8 lights on cheap fluorescent fixtures for the other plants. Many of my plants are kept in glass or plastic bubbles to provide the needed humidity in our open concept house which tends to be very dry in winter.
I have grown my B. bogneri in a north facing window and it did quite well. Since getting back from the Boston Flower Show, where it spent one week just under conference room lights, I have put it under lights to bring it back to health. Begonia luzonensis is behind it.
More to come….