Understanding Hardiness Zones

I’m sure all of us at one point or another have daydreamed about all of the fun, colorful and unique plants that we could spruce up our landscaping with. You Pinterest ideas and find the coolest looking combination of plants, and then you go to your local nursery in search of these plants that you’ve set your heart on, only to be told that the nursery doesn’t carry those plants because they are specific to hardiness zones outside of our own.

Disappointed and not entirely understanding, you nod your head and come to terms with the fact that you will now have to restart your journey of finding the perfect plants to include in your landscaping.

What Are Hardiness Zones Anyways?

Hardiness zones are geographical areas designated to contain a range of climates relevant to the specific growth and survival needs of different plants. The United States Department of Agriculture (USDA) developed a map which splits the United States into thirteen different zones based on annual extreme low temperatures. The USDA even goes as far as to break these zones up into sub-zones (ex. Zone 2a, Zone 2b, etc.) so that gardeners and landscapers across the country can be sure to only plant what will not only grow, but thrive in their area.

Do Hardiness Zones Really Matter?

You might be asking, does it really matter if I am in Hardiness Zone 5, but I want to buy a plant that is specific to Hardiness Zone 6? Many people may be tempted to buy a plant outside of their zone because they like the way it looks or the colors it displays, and then get frustrated at the business they bought it from when the plant does not survive or when it loses all its beautiful features that drew you to the plant in the first place. So, to answer the question, yes!! It does matter!!

All plants present a lovely display unique to their variety, and often this display, whether it is vibrant color, beautiful flowers, deep green foliage, etc., is dependent on the climate. If the plant does not get the right amount of sun and warmth, it will lose its color. Or if a plant gets too cold, it may not flower. That is why the Hardiness Zones were developed– to help people know which plants will grow best in which climates. So, while buying a plant that is marked for Zone 8 when you live in Zone 5 (or any zone that is warmer than the one you are in) may not result in the immediate death of your plant, it definitely will affect the health of the plant, and therefore the plant will likely lack many of the qualities that made it so beautiful and intriguing.

You can, however, plant something that is hardy to zone 3 in zone 5. This is because a zone 3 plant will be able to withstand temperatures much colder than zone 5 will ever experience, so the plant will be fine. So, you can always plant something from a colder zone in a warmer zone, but you cannot plant something from a warmer zone in a colder zone, as a warm-weather plant will not be able to withstand the extreme temperatures of a hardiness zone that is colder than the one they are rated for.

How To Read A Plant Hardiness Zone Map

This task is really very simple. If you do a Google search, the first result will likely be a map of the designated hardiness zones with a legend on one side explaining which colors are correlated to which zones.

Simply find your place on the map, and the color of your area will tell you the annual average extreme minimum temperature range of that area. Here in Fort Collins, Colorado, we are in Zone 5b, with extreme temperatures reaching as low as -10 to -15 degrees Fahrenheit, on average.