LOL...what a surprise! Iowa is still zone 5...go figure
They should just draw a line when it gets to 6a or so and beyond and write 'COLD AS HELL.'
Eh...who cares anyway...I'm still gonna be growing tropicals my whole life in Iowa. Cold never stopped me yet! I guess a change in climate for you zone 7+ people can make a pretty big difference on what you can overwinter and what protection it requires. However, for us people up farther north, these changes don't really affect the way we do things at all.