My grandpa also grew figs in ground, but in Chicago. He used a wood box filled with hay and a window on top to overwinter. He usually trimmed it back hard. It's my first year with figs in ground, but I'm growing mine in a Japanese low cordon style. For protection I made a raised bed frame with a hardware cloth border around it to keep voles out. I filled it with leaves and hay and covered it with a tarp to protect from the wind. Fingers crossed it will survive!