Although I can't make a blanket recommendation to do this, I have
overwintered thyme for 3 winters (including 22 below zero last winter) in an
18 square pot - albeit in a somewhat sheltered location.
This is zone 5/6 usually.
"Ann" You can't plant it in the ground somewhere? It'll do better
there.....
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Ann, Gardening in zone 6a
Just south of Boston, MA
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