The USDA uses the Plant Hardiness Zones, which offer 10 fundamental classifications (Zones 1 to Zone 10) across the country to assist growers in determining which varieties are best suited for their environment. The zones are determined by the annual minimum temperatures on average.
Colorado is in Zone 4 to 6. As a result, it is likely that some perennial plants that grow continuously in other Zones will freeze and perish during the harsh winters in Colorado. -30 to -20 F are the typical low temperatures in the mountains in Zone 4. Colorado’s plains are in Zones 5 or 6, with an average temperature of -20 to 10 F.
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What are Plant Hardiness Zones
When you buy a flowering plant…
You may notice a strange phrase on the plant tag that says: “Hardiness zones” or “Zones.”
If you’re wondering, “What does a plant hardiness zone mean? What does that mean?”, you’re in the right place.
At its most basic, a plant hardiness zone tells you whether a plant is likely to survive the winter temperatures in your area.
Understanding this idea is useful because it affects whether or not your plants will grow back.
I like to think of a hardiness zone like a jean size
Consider your favorite pair of jeans for a moment.
They practically fit like a glove when you put them on. They both feel and look good. Your butt looks good because of them.
YOU. LOVE. THEM.
Sure, you could wear a size or two bigger, but they just wouldn’t feel right.
And yes, it’s possible you may be able to s-q-u-e-e-z-e into jeans one size smaller — with the help of some serious Spanx or more repetitions at the gym. Your jeans would, however, REALLY not fit comfortably. In them, you wouldn’t last very long.
The sweet spot exists, though.
The size you need is in your favorite pair of jeans.
Your garden is like your beloved pair of denim: It has a sweet spot too
Its “size” is known as its hardiness zone.
And that zone number tells you which plants should be the right fit for surviving winter temperatures and returning to your garden next year.
Although they are less likely to come back, you can try planting flowers that don’t belong in the plant hardiness zone of your garden.
Luckily, you don’t have to become a meteorologist to figure out your zone
The U.S. Department of Agriculture (USDA) has developed an easy method to assist you in making plant selections for your garden.
It’s called the “USDA Zone Map for Plant Hardiness.”
Your home has essentially been given a zone. The coldest temperatures that are forecast for your area determine your zone.
As long as you choose plants that match your zone, your plants should be strong enough to survive winter temperatures in your area.
The opportune word here is “should.” Hardiness zones are based on the expected coldest temperatures in your area. However, Mother Nature has been known to exceed the coldest temperature ranges, as was the case with the recent arctic blast that affected much of the United States. in There are additional factors that may affect whether your plants survive the winter in the West, which could be as late as February 2021. The key takeaway? Plant hardiness zones are useful, but they are not perfect.
What Zone is Colorado
Plant hardiness zones in Colorado are 7, 6, 5, 4, and 3.
If you’re unfamiliar with plant hardiness zones, they indicate whether your flower plants will likely survive the region’s coldest winter temperatures and return the following year.
Which plant hardiness zone does your Colorado garden fall under? You can see the USDA Plant Hardiness Zone Map for Colorado below to get a better idea of where you live.
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 >>
Areas with warmer winters have higher zone numbers. They’re in the green. Areas with colder winters have lower zone numbers. They have pink and purple colors.
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 Zone 7 of the plant hardiness scale probably applies to the Grand Junction area. Zone 6 pertains to the neighborhood.
- The majority of the Front Range is in zone 5.
- But if you live in the heart of an urban corridor — certain parts of Zone 6a may include Colorado Springs, Denver, Aurora, and Boulder. Things can get warm because of buildings and concrete. Zone 6 also includes some of Pueblo.
- At higher elevations, like up in the mountains, your plants often need to be able to withstand colder winter temperatures. (In Colorado, temperatures decrease by 3 to 4 degrees for every 1000 feet of elevation gain.) The plant hardiness zone number in your garden is probably lower. Zone 4 is where the majority of mountain towns are located. Some are in zone 3, while others 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 In Colorado, your garden could be up to 10 degrees colder than your neighbors who live on nearby mountain or hillside slopes.
In the evening, cold air settles on valley floors as it slides down the slopes.
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 the 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. You could, for instance, incorporate sizable boulders into your garden. Large rocks and boulders can help block wind and radiate heat to nearby plants. Flowers placed along the south and western sides of structures or rock walls frequently receive more heat.
Use Your Zone to Be a Smarter Plant Shopper
When You Buy Plants That You Want to Return Every Year:
- Don’t assume that the plants at the store are right for where you live.
- Check the plant tags to make sure their plant hardiness zones match yours.
- If you’re buying plants online, look for each plant’s hardiness zone in the online description of the plant.
If you choose a plant that doesn’t work in your zone, you might have to replace a dead plant the following year!
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.
In order to compensate for colder or warmer conditions, you might want to move up or down a zone.
Just bear this in mind as you receive your Colorado hardiness zone!