Danbury, CT planting zone & frost dates
Danbury is in USDA hardiness zone 6b. The last spring frost usually comes around April 20 and the first fall frost around October 20, for a growing season of about 181 days.
Planting calendar for Danbury
Dates are counted from the average last spring frost (April 20) using the typical timing recommended by U.S. extension services. Warm-season crops go out only after the danger of frost has passed and the soil has warmed.
| Crop | When |
|---|---|
| Tomatoes | Start seeds indoors: Feb 23 – Mar 9 Transplant outdoors: Apr 27 – May 4 |
| Peppers | Start seeds indoors: Feb 9 – Feb 23 Transplant outdoors: May 4 – May 11 |
| Eggplant | Start seeds indoors: Feb 9 – Feb 23 Transplant outdoors: May 4 – May 11 |
| Broccoli | Start seeds indoors: Feb 9 – Feb 23 Transplant outdoors: Mar 23 – Apr 6 |
| Cabbage | Start seeds indoors: Feb 9 – Feb 23 Transplant outdoors: Mar 23 – Apr 6 |
| Onions (sets) | Plant outdoors: Mar 23 – Apr 6 |
| Peas | Sow outdoors: Mar 9 – Mar 23 |
| Spinach | Sow outdoors: Mar 9 – Mar 23 |
| Lettuce | Sow outdoors: Mar 23 – Apr 6 |
| Carrots | Sow outdoors: Mar 23 – Apr 6 |
| Potatoes | Plant outdoors: Mar 23 – Apr 6 |
| Beans | Sow outdoors: Apr 27 – May 4 |
| Sweet corn | Sow outdoors: Apr 27 – May 4 |
| Cucumbers | Sow outdoors: Apr 27 – May 4 |
| Squash & zucchini | Sow outdoors: Apr 27 – May 4 |
| Basil | Start seeds indoors: Mar 9 – Mar 23 Transplant outdoors: Apr 27 – May 4 |
Fall garden: cool-season crops like lettuce, spinach and kale can be sown again around Aug 25 (8 weeks before the average first fall frost on Oct 20).
Useful for zone 6b gardens
- Seed starting kit with dome — to start seeds indoors before the last frost
- LED grow light for seedlings — stops leggy seedlings
- Frost cloth / plant covers — for late spring and early fall frosts
- Soil thermometer — warm-season crops need soil above 60°F
- Cold frame / mini greenhouse — adds weeks to a short season
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Frost risk in detail
| 90% chance | 50% chance | 10% chance | |
|---|---|---|---|
| Last 32°F frost in spring is after | Apr 7 | Apr 20 | May 6 |
| First 32°F frost in fall is before | Nov 4 | Oct 20 | Oct 5 |
How to read it: in spring there is a 10% chance of a frost after May 6, so that is a safe date for tender plants. In fall there is a 10% chance of frost before October 5. A hard freeze (28°F) usually ends around April 7.
Hardiness zone by ZIP code in Danbury
- 06810 zone 6b
- 06811 zone 6b
- 06813 zone 6b
Nearby cities
- New Fairfield zone 6b, last frost Apr 20
- Wilton zone 7a, last frost Apr 17
- New Canaan zone 7a, last frost Apr 17
- Southbury zone 6b, last frost Apr 25
- Westport zone 7a, last frost Apr 17
- North Stamford zone 7a, last frost Apr 17
- Norwalk zone 7a, last frost Apr 17
- East Norwalk zone 7a, last frost Apr 17
Questions
What growing zone is Danbury, CT?
Danbury is in USDA Plant Hardiness Zone 6b (average extreme winter low -5°F to 0°F), according to the USDA 2023 map.
When is the last frost in Danbury?
The average last spring frost (32°F) in Danbury is April 20. There is still a 10% chance of frost until May 6.
When can I plant tomatoes in Danbury?
Transplant tomatoes outdoors 1–2 weeks after the average last frost: around Apr 27 – May 4. Start seeds indoors 6–8 weeks before the last frost.
Frost dates: NOAA U.S. Climate Normals 1991–2020, station Danbury, CT (USC00061762), 2.8 km (1.7 mi) from the city center, elevation 123 m, based on 25 years of records. Hardiness zone: USDA Plant Hardiness Zone Map 2023 for the ZIP code nearest to the city center. Microclimates (valleys, hills, cities, coasts) can be warmer or colder: check the local forecast before planting. How we calculate the data.