If you cover the plant with a clear bowl or something it should be fine in the cold, but if you want to bring it inside temporairly you can pick up compact flourescent lights, the ones that fit in regular light sockets that are spiraled between 1 regular daylight CFL a few inches from the top of the plant should be plenty of light for it to grow at that size but thick clay soil is not ideal for the roots. Ideally you want a light airy soil mixture that drains well and is not clumpy