dumb question - because I've got some. I haven't lifted them in 3 years, and they keep coming back! We've just had one of the coldest winters ever in this area, too.
BUT - I don't like them. The bloom is smaller and duller in color than the tag indicated. I'd like to dig them, pot them up, and sell them at our garden club sale since they are hardy in this area. (I didn't think there were any that are!) But I know zip about dahlias.