After being touched by frost a couple of times, our Brussels sprouts are ready to be picked. Frost seems to sweeten some fruits and vegetables, and Brussels sprouts seem to benefit from a bit of light frost. Like all of the cole crops they do just fine in light frosts. Some extremely hardy cole crops like kale will actually winter-over if covered by early insulating snow. Usually winters in Minnesota are too severe for any annual crop to winter, but when we lived in Nebraska the kale could often be dug from the snow and eaten in the winter.
With most vegetables canned or frozen, the potatoes and onions dug, and the grapes fermenting away in the wine carboy, only a few hardy members of the cabbage family remain to lend freshly picked food to the table. Summer seems way too short!