Thanks everyone.
Evan, The Mule palm is hardy to zone 8b and drought tolerant. I have 50 of them up to 15 gallons size on San Juan Island WA Zone 8a and they are handling the temps fine but the constant rain for the 3 months in the winter is not good. The constant wet feet are not good for these palms. In 2010 we had a bad winter and most of them where burned and I had to bring them indoors. I would say they are bullet proof in a zone 8b.
