I moved to Wyoming from the Midwest over 20 years ago. I thought I understood what ‘arid’ meant, but it took two failed vegetable gardens to really get through to me.
Sunset’s Western Gardens does a pretty good job of describing our climate:
“…this zone sees January temperatures from 0-12 degrees F with extremes between -30 and -50. Zone 1b lies east of the Great Divide, where the continental climate reigns supreme. Arctic cold fronts sweep through 6 to 12 times a year, sometimes dropping temperatures by 30 or 40 degrees in 24 hours. The summer growing season tends to be warm and generous at 110 to 140 days long, but constant winds call for windbreaks and shade trees….”
I might argue with their use of the term ‘generous’ when applied to our growing season. The old timers will tell you not to plant vegetables before Memorial Day, and I have learned this is a good rule of thumb. As far as the end of the growing season, it is anybody’s guess. If you garden out of town you may experience killing frost a month or more before the town gardeners. You can pretty much bet on vegetable gardens being done by the end of September, but many perennials such as garden mums and Asters will still be blooming through October.