Kieffer pear trees in Colorado
Thanks for your question about planting pearsp trees. What issues are important to growing fruit trees at higher altitudes are how cold it gets, and the number of warm days during the growing season. Keiffer pear trees are hardy in zones 4-9. (You can read about them here: https://www.arborday.org/trees/treeguide/TreeDetail.cfm?ItemID=895) But an Extension publication indicates they should be okay if you plant them in the right location: http://planttalk.colostate.edu/topics/fruits/1217-fruit-trees-colorado/ You also need to consider potential problems with pears, described here: http://planttalk.colostate.edu/topics/fruits/1205-pears/ I hope this is helpful. If you still have questions, I suggest you call your county Extension office, since the Ask an Expert route didn’t appear to get you a fast response. Good luck!