Bummer, I hope they make it too.
Maybe next time make a closed ends tunnel out of wire fencing/chickenwire? Depending on what you want, you could either make it out of large opening that the garlic could grow through, or small opening like chickenwire or hardware cloth that could double as strawberry tunnel to protect the berries from birds, etc.
Unless the garlic you planted is southern cold sensitive varieties like turban, I think garlic doesn't really need a plastic (or glass) tunnel. And even then, the garlic source I got the turban seed garlic from said it might be enough to just plant them deeper and mulch well even for my area... And I think winter lows are a little less severe in TN (well normally, not sure about THIS winter).
I put open ended vented plastic over my garlic bed planted with turban. Not sure if that is doing anything, but I will find out.
Last year, I tried sowing Walla Walla onion seeds in the fall and covering with plastic tunnel. I doubled the plastic on one end but didn't have enough to double on the last 2 feet of the other end of the tunnel. Guess what, only the ones planted in the last two feet survived. Though it was only the one time experience, my guess is that doubled section got too hot on sunny days and prevented them from properly hardening off/going dormant to survive the extreme freezing nights.
(Ugh this is one of my rambling thought posts, and I'm not sure if the paragraphs are in correct and logical order, switch them around to make most sense, please)
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