The rockii tree peony can bloom successfully in the temperature of -43℃ and spread as far as 53’N. We set up many peony nurseries for demonstration in Harbin (45’N), Changchun (43’N), Shenyang (41’N). Moreover, we also prompt rockii successfully to Denmark, Finland, the north of Germany, England, north USA, Russia, etc. They all grow very well. So do not worry about your local cold weather, rockii tree peony is very suitable to be planted.