Your zone is similar to mine. I've had about 50/50 success with trying to overwinter hostas in pots. I have an enclosed porch which I usually use, but still lose about half. Do ensure that they aren't too wet as the freeze-thaw cycle is what is fatal to the plants. But if the plant is valuable to you, it's better to sink it into your veggie garden if you can, of cover it with something that will insulate it. I have many pots buried in my veggie garden and more that are sitting on top but covered with unscreened compost that was emptied from a bin this autumn.
