I think this past winter was tough on a lot of plants. One nursery told me the temps dropped way faster than normal - down to the teens in mid-November. Another told me many plants were stressed by long dry periods during the winter, and few people thought to water their trees/shrubs.
I lost all but one helianthemum, which are usually rock solid for me. Plus lavenders (which I tend to think of as an annual anyway), a couple artemesias, hyssop, and a young butterfly bush. Random perennials that succumbed: chamomile, skullcap, fleabane, and Mexican tarragon (dang). Some of these I've had for several seasons and all I can chalk up the loss to is the rather weird winter. Another no-show was atropa belladonna that grew from a seed of the mother plant which died a few years ago and I was nursing the baby along.
How did your plants fare over this past winter?