Derby, CT frost dates
Last spring frostApr 25median date
First fall frostOct 17median date
Growing season175 daysfrost-free
Hardiness zone6bZone 6b
How Derby compares
- In 8 years out of 10, the last spring frost in Derby falls between April 11 and May 10, a 29-day window. The first fall frost falls between October 4 and November 1.
- The median last frost is 4 days later than the Connecticut median of Apr 21.
- Its 175-day growing season is longer than 37% of the 267 Connecticut places with a regular frost season (state median 178 days).
- The last frost is typical for zone 6b, where the median is Apr 22.
- The weather station records an average of 130 nights a year at or below 32°F.
- Compared with Milford, CT, 11 km away, the last frost here is 20 days later than there and the growing season is 40 days shorter.
Frost probability
| Chance of frost after | Date |
|---|---|
| 90% (early) | April 11 |
| 50% (median) | April 25 |
| 10% (safe for tender plants) | May 10 |
| Chance of frost before | Date |
|---|---|
| 10% (early) | October 4 |
| 50% (median) | October 17 |
| 90% (late) | November 1 |
Frost here means 32°F (0°C). A median date means half of years have their last frost earlier and half later.
Planting calendar for Derby, CT
Derby, CT frost dates — last frost Apr 25, first frost Oct 17, zone 6b. whenisthelastfrost.com
Crop
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Start indoors: Jan 31 to Feb 14Transplant outside: Mar 28 to Apr 11
Start indoors: Feb 14 to Feb 28Transplant outside: May 9 to May 23
Start indoors: Feb 14 to Feb 28Transplant outside: May 9 to May 23
Start indoors: Feb 28 to Mar 14Transplant outside: May 2 to May 16
Start indoors: Feb 28 to Mar 14Transplant outside: Apr 4 to Apr 18Sow outdoors: Mar 28 to May 2Plant for fall: Aug 22 to Sep 19
Start indoors: Feb 28 to Mar 14Transplant outside: Mar 28 to Apr 11Sow outdoors: Mar 28 to Apr 11Plant for fall: Aug 8 to Aug 29
Start indoors: Feb 28 to Mar 14Transplant outside: Apr 11 to Apr 25Plant for fall: Jul 11 to Aug 1
Start indoors: Feb 28 to Mar 14Transplant outside: Apr 4 to Apr 18Plant for fall: Jul 11 to Aug 1
Start indoors: Feb 28 to Mar 14Transplant outside: Apr 11 to Apr 25Plant for fall: Jul 11 to Aug 1
Start indoors: Mar 14 to Mar 28Transplant outside: May 16 to May 30Sow outdoors: May 16 to May 30
Start indoors: Mar 14 to Mar 28Transplant outside: May 2 to May 16
Sow outdoors: Mar 14 to Apr 4Plant for fall: Jul 25 to Aug 15
Sow outdoors: Mar 14 to Apr 4Plant for fall: Aug 22 to Sep 12
Sow outdoors: Mar 21 to May 2Plant for fall: Sep 5 to Sep 26
Start indoors: Mar 28 to Apr 4Transplant outside: May 9 to May 16Sow outdoors: May 2 to May 16Plant for fall: Aug 1 to Aug 15
Start indoors: Mar 28 to Apr 4Sow outdoors: May 2 to May 16Plant for fall: Aug 8 to Aug 22
Start indoors: Mar 28 to Apr 4Sow outdoors: May 2 to May 16
Start indoors: Mar 28 to Apr 4Transplant outside: May 9 to May 23
Sow outdoors: Apr 4 to May 2Plant for fall: Jul 25 to Aug 8
Sow outdoors: Apr 4 to May 2Plant for fall: Aug 8 to Aug 22
Sow outdoors: Apr 4 to Apr 25
Sow outdoors: Apr 11 to May 9Plant for fall: Aug 8 to Aug 22
Sow outdoors: Apr 11 to May 2Plant for fall: Aug 22 to Sep 12
Sow outdoors: May 2 to May 23Plant for fall: Aug 1 to Aug 15
Sow outdoors: May 2 to May 16
Transplant outside: May 9 to May 30
Plant for fall: Oct 3 to Nov 7
Start indoorsTransplant outsideSow outdoorsPlant for fallMedian frost dates
When to plant vegetables in Derby, CT
| Crop | Start indoors | Transplant | Sow outdoors | Fall crop |
|---|---|---|---|---|
| Onions | Jan 31 – Feb 14 | Mar 28 – Apr 11 | — | — |
| Peppers | Feb 14 – Feb 28 | May 9 – May 23 | — | — |
| Eggplant | Feb 14 – Feb 28 | May 9 – May 23 | — | — |
| Tomatoes | Feb 28 – Mar 14 | May 2 – May 16 | — | — |
| Lettuce | Feb 28 – Mar 14 | Apr 4 – Apr 18 | Mar 28 – May 2 | Aug 22 – Sep 19 |
| Kale | Feb 28 – Mar 14 | Mar 28 – Apr 11 | Mar 28 – Apr 11 | Aug 8 – Aug 29 |
| Broccoli | Feb 28 – Mar 14 | Apr 11 – Apr 25 | — | Jul 11 – Aug 1 |
| Cabbage | Feb 28 – Mar 14 | Apr 4 – Apr 18 | — | Jul 11 – Aug 1 |
| Cauliflower | Feb 28 – Mar 14 | Apr 11 – Apr 25 | — | Jul 11 – Aug 1 |
| Okra | Mar 14 – Mar 28 | May 16 – May 30 | May 16 – May 30 | — |
| Basil | Mar 14 – Mar 28 | May 2 – May 16 | — | — |
| Peas | — | — | Mar 14 – Apr 4 | Jul 25 – Aug 15 |
| Spinach | — | — | Mar 14 – Apr 4 | Aug 22 – Sep 12 |
| Radishes | — | — | Mar 21 – May 2 | Sep 5 – Sep 26 |
| Cucumbers | Mar 28 – Apr 4 | May 9 – May 16 | May 2 – May 16 | Aug 1 – Aug 15 |
| Zucchini & Summer Squash | Mar 28 – Apr 4 | — | May 2 – May 16 | Aug 8 – Aug 22 |
| Winter Squash & Pumpkins | Mar 28 – Apr 4 | — | May 2 – May 16 | — |
| Melons & Watermelon | Mar 28 – Apr 4 | May 9 – May 23 | — | — |
| Carrots | — | — | Apr 4 – May 2 | Jul 25 – Aug 8 |
| Beets | — | — | Apr 4 – May 2 | Aug 8 – Aug 22 |
| Potatoes | — | — | Apr 4 – Apr 25 | — |
| Swiss Chard | — | — | Apr 11 – May 9 | Aug 8 – Aug 22 |
| Cilantro | — | — | Apr 11 – May 2 | Aug 22 – Sep 12 |
| Green Beans | — | — | May 2 – May 23 | Aug 1 – Aug 15 |
| Sweet Corn | — | — | May 2 – May 16 | — |
| Sweet Potatoes | — | May 9 – May 30 | — | — |
| Garlic | — | — | — | Oct 3 – Nov 7 |
Dates come from the median frost dates and common extension-service timing. Adjust for your soil temperature, microclimate and the varieties you grow.
About these dates
Based on 1991–2020 NOAA climate normals for the Ansonia 1 Ne, CT weather station, 3 km away (elevation 138 ft (42 m)).
Frost dates near Derby
- Ansonia Apr 25 · Oct 17
- Shelton Apr 25 · Oct 17
- Orange Apr 25 · Oct 17
- Seymour Apr 25 · Oct 17
- Milford Apr 5 · Nov 6
- West Haven Apr 17 · Oct 27
- Stevenson Apr 25 · Oct 17
- Oxford Apr 25 · Oct 17
- Monroe Apr 25 · Oct 17
- Beacon Falls Apr 25 · Oct 17
Frequently asked questions
When is the last frost in Derby, CT?
The median last spring frost in Derby, CT is April 25. There is still about a 10% chance of frost after May 10, so wait until then to plant frost-tender crops like tomatoes and peppers.
When is the first frost in Derby, CT?
The median first fall frost is October 17, with about a 10% chance of frost before October 4.
How long is the growing season in Derby, CT?
About 175 days between the median last spring frost and first fall frost.
What planting zone is Derby, CT?
Derby, CT is in USDA hardiness zone 6b.