Where I live in Eastern Europe (44°26′7″), we have acclimatized fig trees. And we have temperatures as low as -20C or even -25C (-4 and -13 Fahrenheit).
My parents who still live in the same house do have a small fig tree they don't bury, and my mother's parents a hundred miles south had a larger one in their backyard. I don't know if burying fig trees in that climate is necessary to be honest, maybe it was just a practice my neighbor brought with him (he was Italian as well).
