Know your zone
February 5th, 2021
It’s often said that the key to successful, sustainable plants is putting the right plant in the right place. But first, you need to know your place. That begins by learning your hardiness zone while you plan your landscape.
This USDA system divides the US into 13 plant hardiness zones—including Alaska, Hawaii, and Puerto Rico—based on the average annual extreme minimum temperature of a region. It’s a rough guide to helping gardeners and landscape professionals choose plants that will grow well in their area.
Much of Colorado falls into zones 4-6, though Colorado's fruit-growing area near Grand Junction can cross into zone 7.
Stay in your zone
Look for these numbers when buying seeds or plants for your landscape. Be realistic; you won’t be successful growing Zone 10 avocadoes in your Front Range backyard. But native plants like rudbeckia hirta, aka black-eyed Susan (pictured above), can add hardy color to your landscape.
Keep in mind that hardiness zone labels can cause some confusion in the Rocky Mountain region. A plant sold as a “perennial” in a big chain store may grow as a perennial in its home zone, but in Colorado zones they would be an annual. Examples include chrysanthemums and verbena.
Zones don’t tell the whole story
Plant health depends on more than just temperature. Soil quality, sun, wind, and drainage can all affect the success of a plant—even if it is labeled for your zone. Keep these variations in mind, and you’ll set yourself and your garden up for success in the growing season.
Of course, consulting with a landscape professional will help you make sense of zones and find the right plants. You can also consider Plant Select, which develops plants that often have low water requirements and are well-suited to Colorado’s harsh growing conditions. Any reliable plant source should be able to provide the zone information to help you make your choices.