The United States Department of Agriculture Developed the Plant Hardiness Zone Map for Landscapers and Gardeners to Use as a Guide
Ever wonder why your dahlia’s droop or your winterberry wilts? Before you blame yourself for having a “brown thumb,” look at your climate. Like people, some plants thrive in strong sunlight, while others prefer the cold.
With some help from the USDA, we can turn your thumb and garden green again. The United States Department of Agriculture developed the hardiness zone map for landscapers and gardeners to use as a guide. This map is essential because gardeners plant seeds and starter-plants from all over the world. The hardiness zone map helps you get a feel for whether a variety of plant will thrive in your location.
Each zone is defined by the lowest winter temperatures in a region– the lower the number, the colder. The zones are also calculated by elevation, snowfall, and rainfall… anything that affects growing conditions. The hardiness zone map offers excellent guidelines for planting.
Finding Your Growing Zone
The easiest way to find your hardiness zone is to visit the interactive zone map and enter your zip code. Once you’ve determined your zone, then the fun begins.
Use the Hardiness Zone in my Garden
Once you know your growing zone, you’ll want to check on your first and last frost dates to get the full picture. You can start many seeds in indoor using seed starter kits. You can do this approximately 6 weeks before your area expects the last frost of the season. This will give you a head start on spring planting. When selecting annuals, your hardiness zone only dictates when you can sow seeds. Since annuals only last for the growing season, they’ll need to be re-planted each year from seed.
But, when looking at perennial plants, shrubs, and trees, your hardiness zone is critical to their survival. After you’ve entered your growing zone into the Park Seed interactive map, browse through flower and perennial seeds. You will see a little green checked box appear in the lower left-hand corner of all the varieties particularly well-suited to your zone. Park Seed will only ship plants and seeds when it’s safe to put them in the ground. This is especially helpful while you’re still learning about growing zones and planting schedules.
Extreme northern gardeners may find themselves frustrated by the limits of many flowering varieties, but even they have some vibrant options: delphinium do well in zones 3 to 7, achillea and sempervivum varieties will thrive from zones 3 to 8. Asclepias, echinacea, and peonies are suited for zones 3 to 9.
These ranges may seem generous, but the zones become critical when you live on either end of the extreme. Many perennials that survive cold winters will not tolerate hot summers (Arizona, Texas, and Florida, here’s looking at you). For long, hot summers, you will need to find perennials that are drought-tolerant. Consider kniphofia or penstemon for zones 4 to 9, buddleia or coreopsis for zones 5 to 9, agastache for zones 6 to 10.
Why Plant Perennials?
There’s more to gardening than growing edible annual and perennial plants. Even if they aren’t delivering edible fruits or flowers, perennials serve a vital purpose in the garden: attracting pollinators. Beautiful bloomers bring a smile to gardeners’ faces each spring, but they also bring the birds and bees to the yard. A vegetable garden is only as prolific as its pollinators. The more you attract bees, butterflies, and hummingbirds into the garden the more bountiful it will be.
Sure, it takes a little effort to understand a heat zone map and look for the right plants for your area, but you’ll save yourself in the long run by not planting anything that won’t survive in your climate.
