they WILL be fine even if you lived as far north as one can get before heading south again! my garlic both hardneck and soft and elephant usually sprout before spring in fact i was in the garlic patch today id say about 1/3 have sprouted they are very very very tolerant of the cold in some areas they may get have a little "freezer burn" but will regrow again in the spring, however in your zone 5 you may consider mulching it with leaves or straw this will supress weeds conserve water protect against winter extremes and above all give you pease of mind :) dont worry your garlic will be fine

I agree with salmonslayer. During most of my 30 yrs or so of growing garlic, I have seen shoots come up during winter/fall warm spells and they do just fine. I use about eight inches of straw mulch and do not bother to remove it in the Spring. The garlic shoots are strong enough to poke through it. I do remove the mulch from my shallots which are a bit weaker in the leaf department. Good luck and enjoy your garlic beginning next July.

Thank you...I can throw lots of ground up oak leaves...we have tons...other than that pine needles are everywhere...
I sniped one of the sprouted thin leaves...it tastes so good, it felt like spring...martha/zucchini

From what I've seen so far, it seems like cold temperatures are never an issue for the garlic however I like to make sure they are at least a couple inches deep with some leaf mulch on top to make sure the freeze and thaw cycle doesn't cause bulbs to get lifted out of the ground.

I am in the snow belt under the great lakes so there's almost always a layer of snow protection, but I've never seen foliage damage from garlic before. Maybe I'm just growing the hardiest types.