USDA Plant Hardiness Zones: What are they?
magine the United States as a giant patchwork quilt, each square representing a different climate zone. Thirteen zones range from Alaska to Puerto Rico, representing a 10°F difference in the average annual minimum temperature. You can reference the official growing zone maps on the USDA website anytime.
Half zones exist along with the thirteen different zones, ranging from coldest (zone 1) to warmest (zone 13). The zone is divided into “a” and “b,” representing a five-degree difference within each area.
The USDA updates the Plant Hardiness Zone map approximately every ten years, taking into account changes to the climate. The most recent update was in 2023.
Using the Planting Zone Map
Coldest planting zones 1-4
Zones 1 through 4 all fall in the negatives for annual minimum temperatures. These regions are in Alaska, the Northeast, the Northern Midwest, and mountain elevations. Below is a look at the average temperatures and examples of plants that thrive in these zones.
- Zone 1: Below -50°F: Think rugged evergreens like spruce and fir trees, hardy perennials like Siberian iris, and creeping juniper.
- Zone 2: -50°F to -40°F: Here, you’ll find cold-hardy specimens like dwarf Alberta spruce, fragrant winter jasmine, and colorful winterberries.
- Zone 3: -40°F to -30°F: Explore the world of cold-tolerant plants such as snowball viburnum, Japanese maple, and the resilient daylily.
- Zone 4: -30°F to -20°F: To add a splash of color to your garden beds, look for early bloomers like forsythia, tulips, and lilacs.
Moderate planting zones 5-8
Zones 5-8 represent areas with relatively moderate climates, where temperatures are neither extremely cold nor excessively hot. These are the southern Northeast states, the Midwest, the Great Plains, and parts of the Pacific Northwest.
- Zone 5: -20°F to -10°F: Embrace the resilience of stalwart perennials like hostas, peonies, and phlox as they burst into bloom.
- Zone 6: -10°F to 0°F: Revel in the bounty of plants such as hydrangeas, roses, and lavender that thrive in this temperate climate.
- Zone 7: 00°F to 10°F: Embrace the diversity of options, from colorful azaleas and camellias to fragrant magnolias and ornamental grasses.
- Zone 8: 10°F to 20°F: Think palm trees, citrus fruits, and hibiscus flowers, transforming your garden into a tropical oasis.
Warm planting zones 9 – 13
The warm planting zones (Zone 9 to Zone 13) in the USDA Plant Hardiness Zone map represent regions with mild to hot climates and generally frost-free winters. You’ll find these in the Southeast, Southwest, Hawaiian islands, and Puerto Rico.
- Zone 9: 20°F to 30°F: Dive into the world of exotic plants like bougainvillea, banana trees, and orchids, creating a lush landscape that knows no season.
- Zone 10: 30°F to 40°F: Explore the wonders of tropical flora such as mango trees, bird of paradise, and plumeria, turning your garden into a sun-drenched paradise.
- Zone 11: 40°F to 50°F: This tropical climate is ideal for coconut palms, orchids, bromeliads, heliconias, ginger, and taro.
- Zone 12: 50°F to 60°F: Rainforest trees, ferns, mosses, epiphytes (plants that grow on other plants), and many exotic tropical plants.
- Zone 13: Above 60°F: Tropical rainforest plants, rare and exotic tropical fruits, rare palms, and a wide variety of tropical flowers and foliage plants.
How to use your planting zone
Armed with your USDA planting zone knowledge, you can now embark on a gardening journey tailored to your unique climate. Use your growing season to determine the best time to plant, which plants will likely thrive, and when to expect those pesky frost dates.
Enter your zip code into a USDA Hardiness Zone map, and let the adventure begin. With your newfound planting wisdom, you’ll cultivate a garden that blooms with beauty and vitality, no matter the season!
