What is the Hardiness Zone? Learn How to Find Your Gardenia’s Hardiness Zone!
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What Do Plant Hardiness Zones Mean?
A plant’s hardiness zone is a classification of climates in which the plant will typically grow best. It is based on a plant’s ability to withstand cold temperatures and periods of frost, as well as its need for sunshine. The United States Department of Agriculture (USDA) has developed eleven hardiness zones, based on average monthly minimum temperatures. The zones are color-coded according to their heat requirements: Most plants are hardy in at least seven zones, though they will perform better in some areas and worse in others. For most landscape plants that you buy from a store or garden center, the planting instructions will list the zone for your area. These zones are as follows:
Zone 1: These plants can only tolerate brief exposures to very cold temperatures and must be grown in a greenhouse or other warm environment.
Zone 2: These plants can only tolerate very short exposures to severe cold and must be grown in a greenhouse or other warm environment.
Zone 3: These plants can tolerate short exposures to severe cold, but should be moved to warmer climates if they are expected to endure extended periods of cold weather.
Zone 4: This is the transitional zone between Zones 3 and 5 and is typically found near the middle of the United States. Plants in this zone can tolerate brief exposure to cold temperatures but should be moved to warmer climates if they are expected to endure extended periods of cold weather.
Zone 5: This is the most common zone in the United States and Europe. Plants in this zone can withstand brief exposure to moderate cold, but should be moved to warmer climates if they are expected to endure extended periods of cold weather.
Zones 6-9: These plants can tolerate brief exposure to cold temperatures, but should be moved to warmer climates if they are expected to endure long periods of cold weather.
Zone 10 is only found in a few states near the equator. The plant can tolerate brief exposure to very cold temperatures.
Zone 11 is the most northerly zone and the least hardy of all. The plant will not tolerate any exposure to cold weather and should be grown indoors.
Zone 12 is found along the Gulf of Mexico. The plant can tolerate brief exposure to moderate cold and should be moved to warmer climates if they are expected to endure extended periods of cold weather.
Zone 13 This zone is found in the southwestern United States and Mexico. The plant can tolerate brief exposure to cold temperatures and should be grown in a warmer climate if they are expected to endure extended periods of cold weather.
If you live somewhere outside of those eleven USDA zones or have specific growing conditions that require a different zone, then consult plant HardinessZone Finder.com to determine what range of temperatures your plant should be able to tolerate.
What Are the Benefits of Planting a Gardenia in a Hardiness Zone?
If you live in one of the 11 USDA hardiness zones, planting gardenias there is likely to be beneficial. Plants within these zones generally have shorter growing seasons and cooler temperatures than those outside this zone range. This means that your gardenia will typically grow faster and larger indoors, where light intensity and duration are higher levels than outdoors.
In addition Gardenias also benefit from a regular supply of sunlight, as they are evergreen flowers. Planting them in an area with ample natural light will help them to grow and blossom in the same shape year after year.
USDA Plant Hardiness Zone Temperature Chart
| Zones | Temperature |
| Zone 1a | -60 to -55°F or -51 to -48.3°C |
| Zone 1b | -55 to -50°F or -48.3 to -45.6°C |
| Zone 2a | -50 to -45°F or -45.6 to -42.8°C |
| Zone 2b | -45 to -40°F or -42.8 to -40.0°C |
| Zone 3a | -40 to -35°F or -40.0 to -37.2°C |
| Zone 3b | -35 to -30°F or -37.2 to -34.4°C |
| Zone 4a | -30 to -25°F or -34.4 to -31.7°C |
| Zone 4b | -25 to -20°F or -31.7 to -28.9°C |
| Zone 5a | -20 to -15 °F or -28.9 to -26.1 °C |
| Zone 5b | -15 to -10°F or -26.1 to -23.3°C |
| Zone 6a | -10 to -5°F or -23.3 to -20.6°C |
| Zone 6b | -5 to 0°F or -20.6 to -17.8°C |
| Zone 7a | 0 to 5°F or -17.8 to -15°C |
| Zone 7b | 5 to 10°F or -15 to -12.2°C |
| Zone 8a | 10 to 15°F or 12.2 to -9.4°C |
| Zone 8b | 15 to 20°F or -9.4 to -6.7°C |
| Zone 9a | 20 to 25°F or -6.7 to -3.9°C |
| Zone 9b | 25 to 30°F or -3.9 to -1.1°C |
| Zone 10a | 30 to 35°F or -1.1 to 1.7°C |
| Zone 10b | 35 to 40°F or 1.7 to 4.4°C |
| Zone 11a | 40 to 45°F or 4.4 to 7.2°C |
| Zone 11b | 45 to 50 °F/7.2 to 10 °C |
| Zone 12a | 50 to 55°F or 10 to 12.8°C |
| Zone 12b | 55 to 60°F or 12.8 to 15.6°C |
| Zone 13a | 60 to 65°F or 15.6 to 18.3°C |
| Zone 13b | 65 to 70°F or 18.3 to 21.1°C |
Gardenia Varieties
| Popular Varieties | USDA Plant Hardiness Zone |
| Large-Sized Gardenia | |
| Cape Jasmine ‘Aimee Yoshioka’ | Zone 8-11 |
| Cape Jasmine ‘Belmont’ | Zone 7-11 |
| Cape Jasmine ‘Fortuniana’ | Zone 8-11 |
| Cape Jasmine ‘Miami Supreme’ | Zone 8-11 |
| Cape Jasmine ‘Mystery’ | Zone 8-11 |
| Medium-Sized Cultivars | |
| Common Gardenia | Zone 8-11 |
| Cape Jasmine ‘August Beauty’ | Zone 8a-11 |
| Cape Jasmine ‘Chuck Hayes’ | Zone 7-11 |
| Cape Jasmine ‘Coconut Magic’ | Zone 8-11 |
| Cape Jasmine ‘Daisy’ | Zone 7a-10b |
| Cape Jasmine ‘Frost Proof’ | Zone 7a-11 |
| Cape Jasmine ‘Heaven Scent’ | Zone 6b-9b |
| Cape Jasmine ‘Jubilation’ | Zone 7a-11 |
| Cape Jasmine ‘Pinwheel’ | Zone 6-11 |
| Cape Jasmine ‘Veitchii’ | Zone 8-11 |
| Cape Jasmine ‘Celestial Star’ | Zone 7a-11 |
| Cape Jasmine ‘Double Mint’ | Zone 7a-9b |
| Cape Jasmine ‘Swan Maiden’ | Zone 6b-11 |
| Cape Jasmine ‘Swan Queen’ | Zone 6b-11 |
| Cape Jasmine ‘Fall in Love’ | Zone 7a-11 |
| Cape Jasmine ‘Diamond Spire’ | Zone 7a-10b |
| Cape Jasmine ‘Fool Proof’ | Zone 7a-11 |
| Cape Jasmine ‘Swan Princess’ | Zone 6b-11 |
| Groundcover/ Creeping Varieties | |
| Gardenia ‘Radicans’ | Zone 8-11 |
| Cape Jasmine ‘Buttons’ | Zone 7a-11 |
| Cape Jasmine ‘Crown Jewel’ | Zone 6-11 |
| Cape Jasmine ‘Golden Magic’ | Zone 8-11 |
| ‘Lee Two’ or ‘ScentAmazing’ | Zone 7a-10b |
| Cape Jasmine ‘Four Seasons’ | Zone 8-11 |
| Cape Jasmine ‘Kleim’s Hardy’ | Zone 7-11 |
| Variegated Gardenia | Zone 8-11 |