By all accounts in the press, forums and blogs, Polar Joy Tree Rose is a very hardy rose, rated at USDA Zone 4. That being stated, you would treat your tree rose as a hardy rose and only need to trim out dead canes, maintain a good shape and promote new flowers in the same manner you would if that rose was growing not growing on a standard. Tree roses can make quite a show in the garden and around a patio.
Sincerely, Richard
