I agree with this method from
@dyzzypyxxy 
"Another method to over-winter would be to dig a hole and bury the pots (the ones that they are in now, not the giant ones Big Grin ) and mulch deeply over the whole thing. Then in spring if you still want them in the giant pots, they'd be easy to transplant and not rooted into that blasted clay."
The plant will suffer less doing it this temporary way; when the spring comes the plant will be in 'grow mode' and should thrive once you finally get in planted in-ground.
