Hi Tom,
Thank you for your question about Sister’s planting climate zone.

The following OSU Extension publication about gardening in Central Oregon’s climate discusses hardiness zones and states the following:
“There are numerous factors that contribute to whether or not a plant will survive besides minimum temperatures. Some of these factors include soil type, rainfall, heat tolerance and exposure to wind and sun. According to the USDA Hardiness Zone map, Central Oregon is placed in Zone 6 (–10 degrees Fahrenheit to 0 degrees Fahrenheit). However, this is really oversimplified given our many microclimates. The following chart is a more accurate guide to use when looking at plant hardiness for Central Oregon. Just remember to think about microclimates within your own landscape.”

When selecting plant material for your landscape, the chart indicates that the USDA hardiness zone for Sisters is 3-5. Gardening in Central Oregon's climate | OSU Extension Service (oregonstate.edu)

The OSU Deschutes County Extension website provides many helpful publications about gardening in Central Oregon. Following is a link to this website, which will direct you to a variety of gardening topics specific for our geographic area and climate.
Central Oregon Garden Publications | OSU Extension Service (oregonstate.edu)

If you need additional information, I recommend you call the Deschutes County OSU Extension office in Redmond at<personal data hidden>. Ask to speak with Amy Jo Detweiler (oregonstate.edu), a member of the Horticulture Staff. Amy Jo welcomes your home garden questions and is a great resource.