I don't have a root cellar but I do have an area in the basement that is dark, cool and dry. I never seem to be able to keep my garlic past Thanksgiving and rarely Christmas. What is your shelf life as you have a good amount of garlic.
I give a lot of it away and also use a bunch in October for replanting. The rest I would say keeps till January-February. At that point I slice and dehydrate whatever remains. The garlic chips get used in marinades and also garlic powder.