If you grow them in the ground, I would suggest what I do, which is just chop it down low enough that you can cover it when the temps are going to drop below freezing. It is literally one of the fastest growing plants in nature. It will come back stronger and still bloom for you by late spring. If you look at the thread I started titled "still going" you can have a idea of the growth rate. Mine was easily 10-12' tall and 8-10' wide before we got our winter storm. I cut it to the ground and it's already about 8' tall and 5' wide again. It's a very hardy plant, don't be afraid to experiment with different ways to make your life easier.
