Looking for advice on apple rootstocks
I live in northern Alberta and I am looking for some advice or recommendations for good apple rootstocks that can handle at least -50C. I have seen -58C, but that was about a decade ago, still a possibility I will see it again though.
Most garden centers are much further south and their rootstocks are only rated for zone 3 and I know zone 3 shrubs don't survive even a warm winter (I have tried).
Due to the sheer number of deer and moose, I will need a tree that can hit at least 10 feet, 15 feet wouldn't bother me although I am hoping it won't go past 20 feet. I am hoping for one that grows fairly fast the first few years to get the top branches out of range of the 4 legged tree destroyers.