It should do fine just sitting out there all by its lonely. Once the ground freezes its root activity will shut down and it will be dormant until spring.
Sometimes greens don't emerge until spring even though they are making roots in the fall.

I have to disagree with oldroser. In Arizona zone 6b, you are going to have warm enough weather during much of the winter to have some root growth, at least. As with all plantings in this climate, ornamental and vegetable, water deeply at least once a month if you don't have snow cover. Your garlic will probably survive if you don't water, but you will have significantly smaller heads at harvest time due to the drought stress over the winter.

Catherine