i live in savannah, georgia so it is starting to warm up here now. spring is on the way! i will still need the heater at night and probably here and there during the day for the next month but no extra insulation is going to be needed. i got an oil filled heater a while back and tested it out--it actually does a very good job on its own of warming up the space.
my biggest problem is going to be the heat--in just a few short months it will be HOT again. i think i am going to have to put a window unit in the garage--NOT so much looking forward to the electric bill with that addition, but i'm not sure i have many other options.