USDA Hardiness Zones can be a good way to determine what may be grown in your area; particularly when it comes to perennials that need to survive the winter. However, for some areas, like this one, it may be difficult to determine just what your zone is. For instance, when I enter my zip code HERE, it indicates that I am in Zone 5a. Since I used to live in Zone 5b, and I know that the conditions here are quite different, my gut tells me this is not Zone 5a. After talking with other locals in addition to observing the past 3-4 years of weather, I would consider that my zone is 4a. The “Interactive Map” is a little more detailed, and shows my location closer to Zone 4b. Some local gardeners have suggested it’s best to plant perennials that are hardy to Zone 3. I’m going with that, to be on the safe side. Our first winter here, we did experience one morning of -23 degrees. One thing that has been difficult on some of the nursery websites is that they have automatic zone finders to choose plants hardy for your region. I have had to locate a Zone 3 zip code to enter to those websites to filter for hardier plants. I also had to make a request of one website, when making my order, NOT to send out plants based on my zip code; I told them when I wanted the plants.

Frost dates
are another important thing to consider, particularly for annuals. There are also some internet sources to determine frost dates, but some of these also leave something to be desired. The Farmer’s Almanac “Frost Dates Calculator” is VERY wrong for my location. After entering my zipcode, it shows a location that is about 4,000 feet lower than mine. If I try another zipcode nearby, it shows another location nowhere near us. The First and Last Freeze/Frost Dates calculator on is much more accurate, and shows a couple of nearby locations. For my location, it suggests, “Each winter, on average, your risk of frost is from August 22 through July 7. Almost certainly, however, you will receive frost from September 9 through June 20.”  Generally, I consider our Last Frost Date to be June 15th, and our First Frost Date to be September 15th. I watch the weather closely to around those dates to determine whether it may be safe to plant, or whether things will need to be covered and/or harvested.

Here are some weather statistics for our location. We have a weather station located on our site, and have been recording these statistics since late 2014. Shown here are stats for 2015-2017.

This page was written in December 2017, after our first year gardening at high altitude. Please refer to an update written September 2019 regarding my frustration with finding good information about what might grow well in my climate, “Growing Zone Frustration.”