I'm amazed by the information about overwintering. I always grow this plant in my garden, but I have to replace it after every winter that veers closer to zone 8b rather than my official zone 9a (which is their minimum hardiness zone). I guess we "zone-9ers" are so spoiled that we take no overwintering precautions on any plant.
That's hardly a problem, however, because I can always find them in spring for $2.59 at Ace Hardware and start over. They grow quickly and start blooming in summer, continuing through fall. They smell great, in contrast to some salvias, and the blooms are quite vivid.