I'm lucky to have an enclosed sun porch where I can keep the citrus and tropical plants during the winter. The porch is not heated, so the temperature does drop to the low 40s at times. The porch usually stays about 10 degrees above the outside temperature. Luckily, the citrus plants don't mind when the temperature drops. It's a great place for me to overwinter plants. This is the dwarf lime tree that I have had for 3 years. I have to learn how to fertilize it better. I use Growmore organic citrus fertilizer, but I have yet to see this plant produce one lime! I dream of the day that it will. Right next to the lime tree is my potted spearmint plant.