USDA hardiness zones in Connecticut
| Zone | Avg. extreme minimum | ZIP codes | Example cities |
|---|---|---|---|
| Zone 6a | −10 to −5°F | 36 | Torrington |
| Zone 6b | −5 to 0°F | 168 | Hartford, Waterbury, Danbury, New Britain |
| Zone 7a | 0 to 5°F | 61 | Bridgeport, Stamford, New Haven, Norwalk |
| Zone 7b | 5 to 10°F | 5 | — |
Growing zone and frost dates by city
| City | Zone | Frost dates |
|---|---|---|
| Bridgeport | 7a (0 to 5°F) | Bridgeport frost dates |
| Stamford | 7a (0 to 5°F) | Stamford frost dates |
| New Haven | 7a (0 to 5°F) | New Haven frost dates |
| Hartford | 6b (−5 to 0°F) | Hartford frost dates |
| Waterbury | 6b (−5 to 0°F) | Waterbury frost dates |
| Norwalk | 7a (0 to 5°F) | Norwalk frost dates |
| Danbury | 6b (−5 to 0°F) | Danbury frost dates |
| New Britain | 6b (−5 to 0°F) | New Britain frost dates |
| Bristol | 6b (−5 to 0°F) | Bristol frost dates |
| Meriden | 6b (−5 to 0°F) | Meriden frost dates |
| West Haven | 7a (0 to 5°F) | West Haven frost dates |
| Milford | 7a (0 to 5°F) | Milford frost dates |
| Middletown | 6b (−5 to 0°F) | Middletown frost dates |
| Shelton | 6b (−5 to 0°F) | Shelton frost dates |
| Norwich | 6b (−5 to 0°F) | Norwich frost dates |
| Torrington | 6a (−10 to −5°F) | Torrington frost dates |
| Naugatuck | 6b (−5 to 0°F) | Naugatuck frost dates |
| New London | 7a (0 to 5°F) | New London frost dates |
| Ansonia | 6b (−5 to 0°F) | Ansonia frost dates |
| Derby | 6b (−5 to 0°F) | Derby frost dates |
| Groton | 7a (0 to 5°F) | Groton frost dates |
Frequently asked questions
What growing zone is Connecticut in?
Connecticut’s ZIP codes span USDA zones 6a to 7b, and 6b is the most common. Zones vary with elevation and distance from water, so check your own ZIP code.
When should I plant?
Hardiness zones are about winter cold, not planting dates. For timing, use the last spring frost date for your city on our Connecticut frost dates page.