Answer: Gardening in Montana is very challenging as you have probably already figured out. I would suggest you work closely with your local county extension and local, professionally trained, garden center staff to analyze the growing conditions in your new garden spot, and based on that, determine what will have the best chances of thriving for you. Then, select the plants you like best from among those.
The Montana State University extension service does offer a number of publications, many available on line, that would be very helpful to you in the planning stages.
For example, here is information about roses specifically for Montana.
Here is a link to the official page listing the publications and order form for those that are not free on-line.
You may also find the following web pages by Dr. Bob Gough very helpful.
I hope this helps.
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