I have no idea how far north they grow. I do know they are not everywhere, even around here. They seem to pick their spots. I have none on the Box Elders on the north end of our property but they are everywhere on the south end. I think the big thing is you need old trees with scars but, that is just my observation. One cool thing is, once you have found one growing on a scar, look there next year and there will be another one. Best way to spot them is look up. Most of mine grow above eye level.
Happy Hunting!
Last edited by Bill D.; 10/01/15 07:20 PM. Reason: Clarification