> The plants you mention do not grow here in the winter outside of a greenhouse

You're right, they don't. That's why you plant them in the late summer, with a mix of kale, chicory, rape, and other brassicas. The deer and elk eat the greens above ground right up until snowfall and then they dig the turnips and beets out of the ground over the winter as needed. They usually leave the pumpkins for last, but come late January they'll eat every last one.