The info you mentioned on the tag is wrong. There is no way it can survive at -20F. Also, survival at -10F is iffy unless you cover/insulate it very elaborately. Many in Zone 6 have grown it in the ground but needs covering up with insulation. You can search here with 'winter protection' to learn how to arrange for such protection. Even then there is probability of die-back to the ground in some winters. The survival in this case will mean sprouting back from the ground (from roots). Sometimes growing from the ground after die-back to the ground gets delayed thus minimizing chances for ripe fruit from the new growth and more so in location with cool or short summer.