Garlic loves/needs cold weather, so it's really not necessary to move the container into a garage.

Just make sure the container is deep enough and wide enough to give the roots room to grow, and protect it from wild swings in soil temperature (a small pot will freeze quickly and thaw rapidly, especially if it's wet and we get those January thaws). A layer of straw mulch will help.

There are only two good reasons I can think of to do things this way -- you're planning to move in the spring, or you want to force some cloves to eat as g'allions in late winter. If you let the cloves root in a pot kept in a cold place by November and then bring it indoors in Feb, the cloves will start growing edible greens.

Planting in the ground is much more of a sure thing because the growing cloves enjoy the constancy of moisture and temperature 4 inches down. I think leeks are better hardy alliums to handle in containers.

Well its a great idea for a person who doesn't have a garden. I wrote an article on growing in containers. you can check it out here if you want. Jubilee Produce

I grow garlic in 18" containers for clean seed. I grow the main crop in raised beds and the virus load gets too high and the crop starts to show signs of distress so this year I decided that I could probably clean up my seed stock by growing in completely clean soil. I have always grown in containers when I want to preserve a strain, but do not want to commit to a large bed of them. When I checked they yesterday I could see roots just busting out of the drain holes--they might be a bit more work as far as watering and feeding goes (takes more of each), but the results are really worth it to me.