I cut mine back to 4 to 6 in every fall and put leaves over it but im in a much cooler zone than u...someone will hopefully answer thats more experience with your zone

In zone 9, I would not recommend it. We're still pretty warm, and any new growth would be killed by a cold snap. I always try to wait until at least February to prune drastically. That way, you now they are fully dormant, so no chance of new growth damage.