Hi, for what it's worth, most of my gardening is container gardening, it's all my responsibility and I'm not in the best of health, so containers make more things possible for me. Have you ever tried pineapple sage? I'm to the east of you, but the same zone, and it wintered for me along with two other herbs for years before a killer winter finally had its way with them. The pineapple sage grew to be about three feet high when all was said and done, it gets red flowers on it later in the season, bees and butterflies love it, and it makes a great roast chicken! In fact, it became so established that during the hurricane before Sandy, it all begins to blur, my umbrella blew down on top of it, and the stem of the sage plant ripped a hole in the cloth. I also had rosemary that made it through about four winters before a devastating snowstorm sent it to that big artisanal bakery in the sky, and I had a huge tub of lavender as well that I actually brought with me during a move. It was around for about six years before a blizzard killed it. The rosemary by the deck door was wonderful, the aroma when I opened the door on a summer morning, and of course, lavender is lovely, and again, the butterflies and bees loved them all. I brought dried lavender into the house and kept it in a wall vase, and well, rosemary makes great chicken and bread, for starters!
And I know this sounds weird, and no, I can't explain it, but I plant a lot of annual flowers in containers, and for the last three years before I moved, I had snapdragons come back in containers, they're not supposed to, but they did