I was watching P. Allen Smith recently and he also has a home in Arkansas, which is Zone 7 in most parts. To my surprise, he said he leaves his Dahlias in the ground and they come back every year. I haven't been growing them anymore because I thought I had to dig up the tubers. I grew a shorter variety from seed and never dreamed they would bloom so quickly. They were so easy to start and bloomed all summer in our heat! I'm trying dahlias again and can't wait until spring!