I posted this in fruits as well but thought i would try here too. I have a young Kieffer pear that I don't really care for. The tree is still smallish 6', and despite a total lack of care beside some basic pruning it seems to have established and shaped very well. My problem is I am just about out of space in the orchard. I have room for one more pear in addition to the Bartlet we have and this Kiefer. I intend to plant one of the more cold hardy varieties offered by SLN in the open spot. And I need to decide weather to completely top work over the Kiefer to other more interesting and region suitable varieties, or to just tear it out and put something new in. my question is how cold hardy is the woody tissue of a kiefer? We are technically zone 4 but every few years we have cold snaps that are pretty brutal. With trees I like to have faith in thier long term survival and generally plant Z3. Anyone have experience or thoughts on this? I enjoy grafting, and the tree is quite well formed so far, but there isn't much point putting hardy varieties on top of a base that won't hack -25-35F once and awhile.