Canning garlic isn’t usually done, but there are some circumstances where it might be worth a try.
Garlic is one of those crops that usually keeps well on its own. Harvest it in the late fall, braid it and hang it to dry before keeping it all winter in a cool, low humidity environment. The trick is…most vegetables and fruits want a high humidity root cellar. To properly root cellar garlic, you need a completely different root cellar environment, and the book Root Cellaring actually recommends having two completely separate root cellars. Who has space for that?!?!
If your house is moist, or you live in a humid climate, storing garlic can be a challenge.