Zone lookup
What’s my USDA hardiness zone?
Enter your ZIP code and we’ll find your exact zone from the official 2023 USDA Plant Hardiness Zone Map, the one thing every gardener needs to know before buying a plant.
What does a hardiness zone mean?
The USDA divides the contiguous US (plus Alaska, Hawaii, and Puerto Rico) into 13 zones numbered 1 through 13, each 10°F wide. Each zone is further split into “a” (colder half) and “b” (warmer half), making 26 sub-zones in total.
A perennial plant labeled “hardy to Zone 6a” can survive an average low of −10°F to −5°F. If your winters get colder than that, the plant won’t survive outdoors.
Zone hardiness tells you about winter survival. It doesn’t say anything about summer heat, humidity, or drought. A plant can be perfectly zone-hardy but still struggle in your garden for other reasons. That’s why Bloomwise looks at light, water, space, and your preferences alongside zone.
Zone temperature reference
| Zone | Min. temp (°F) | Where |
|---|---|---|
| 3 | −40 to −30°F | Interior Minnesota, North Dakota |
| 4 | −30 to −20°F | Northern New England, Great Lakes |
| 5 | −20 to −10°F | Chicago, Denver, Cleveland |
| 6 | −10 to 0°F | New York City, St. Louis, Louisville |
| 7 | 0 to 10°F | Washington DC, Atlanta, Dallas |
| 8 | 10 to 20°F | Pacific NW, coastal Carolinas, Houston |
| 9 | 20 to 30°F | Central California, Florida Panhandle |
| 10 | 30 to 40°F | Miami, Los Angeles, Hawaii lowlands |
Source: USDA 2023 Plant Hardiness Zone Map (public domain). Zones 1–2 and 11–13 omitted for brevity.
Frequently asked questions
- What is a USDA Plant Hardiness Zone?
- The USDA Plant Hardiness Zone Map divides the US into 13 zones (1–13) based on average annual minimum winter temperatures. Zone 1 is the coldest (interior Alaska), Zone 13 is the warmest (south Florida, Hawaii). Each zone is split into a and b sub-zones, 5°F apart. Knowing your zone tells you which perennial plants can survive your winters without dying back to the roots.
- How do I find my hardiness zone by ZIP code?
- Enter your 5-digit US ZIP code in the lookup tool above. We convert your ZIP to latitude and longitude, then check it against the USDA 2023 Plant Hardiness Zone shapefile to find your exact zone, accurate to the sub-zone (a or b) level.
- What does my hardiness zone tell me?
- Your zone tells you the coldest it typically gets in winter. A plant labeled 'hardy to Zone 6' can survive winters where the coldest night reaches –10°F to 0°F. If your zone is 6 or warmer, that plant should survive outdoors year-round. If you're in Zone 5, that plant will likely die in winter and must be treated as an annual or brought indoors.
- Can I grow plants outside my hardiness zone?
- Yes, in both directions. You can grow Zone 8 plants in Zone 6 by mulching heavily and sheltering them in winter (called 'zone pushing'). You can also grow Zone 4 plants in Zone 8, but they may struggle with hot summers even though they're cold-hardy. Microclimates (south-facing walls, urban heat islands, low frost pockets) can shift your effective zone by 1–2 zones.
- Is the USDA Hardiness Zone the only thing that matters?
- No. It's the most important factor for winter survival, but heat tolerance, humidity, soil type, rainfall, and sunlight hours matter just as much for a plant to thrive. Two gardens in the same zone can have very different growing conditions. That's why Bloomwise also considers your space, light, and watering habits when recommending plants.