Colorado has 5 plant hardiness zones: 7, 6, 5, 4 and 3.
If you’re new to plant hardiness zones, they tell you whether your flower plants are likely to survive the coldest winter temperatures that are expected in your area and come back next year.
(For the full scoop on hardiness zones, check out: What is a plant hardiness zone? And why they matter)
So, what plant hardiness zone is your Colorado garden? It depends on where you live, as you can see in the USDA Plant Hardiness Zone Map for Colorado below. (Scroll down this page for specifics.)
Areas with warmer winters have higher zone numbers. They’re in green. Areas with colder winters have lower zone numbers. They’re in purple and pink.
Let’s look at plant hardiness zones in Colorado in broad strokes:
- If you live in the hottest parts of Colorado — like the southwest corner and parts of the Grand Junction area — you’re likely in plant hardiness zone 7. Surrounding areas are in zone 6.
- The majority of the Front Range is in zone 5.
- But if you live in the heart of an urban corridor — like certain parts of Colorado Springs, Denver, Aurora and Boulder — you may be in zone 6a. Buildings and concrete can heat things up. Parts of Pueblo are in zone 6 too.
- At higher elevations, like up in the mountains, your plants often need to be able to withstand colder winter temperatures. (For every 1000 feet you go up in elevation in Colorado, temperatures drop about 3 to 4 degrees.) Your garden will likely have a lower plant hardiness zone number. The majority of mountain towns are in zone 4. A few are in zone 3 and a few are in zone 5.
There are exceptions to the “it gets colder as you go higher” guideline.
For example, if you live on a valley floor in Colorado, your garden can be up to 10-degrees COLDER than your neighbors on nearby hillsides or mountainsides.
Cold air slides down the slopes and settles on valley floors at night.
Another exception…
If you live on a north-facing slope, your garden may be a lot cooler and damper than the dry, heat-gathering gardens on south- and western-facing slopes.
And one more exception… It’s possible to create “microclimates” in your garden that are warmer than the surrounding area. For example, you could include large boulders in your garden. Boulders and large rocks can radiate heat to surrounding plants and help block winds. Often times, flowers planted along the south and western sides of buildings or rock walls can receive more heat too.
So, what’s the takeaway? Your local surroundings play a role.
The zone you’ll get from the USDA may not accurately reflect what’s going on in your individual garden in Colorado.
You may want to adjust down a zone (for colder conditions) or up a zone (for warmer conditions).
Just keep this in mind as you get your Colorado hardiness zone below!
To get the Colorado plant hardiness zone for your garden:
Click to the USDA website here and enter your zip code in the upper left >>
