When to plant in Derby, CT
USDA Zone 6bHere are the average frost dates, USDA hardiness zone, and a month-by-month planting calendar for Derby, Connecticut — all computed from Derby's nearest NOAA weather station.
Zone 6b means Derby sees real winter cold, but a good range of perennials survive; the frost dates above govern when annual vegetables go out.
Frost probability
ANSONIA 1 NE · 1991–2020The date the last spring and first fall frost occur, by threshold and probability. A 90% date is later in spring — and earlier in fall — than a 10% date; the 50% · 32°F row is what most gardeners plan around. These are Derby’s own odds, recorded at ANSONIA 1 NE.
| Threshold | SPRING 10% | SPRING 50% | SPRING 90% | FALL 10% | FALL 50% | FALL 90% |
|---|---|---|---|---|---|---|
| 36°F | May 22 | May 8 | Apr 24 | Sep 27 | Oct 7 | Oct 21 |
| 32°F | May 10 | Apr 25 | Apr 11 | Oct 4 | Oct 17 | Nov 1 |
| 28°F | Apr 27 | Apr 10 | Mar 30 | Oct 14 | Oct 30 | Nov 13 |
Download this table as CSV ↓ — every threshold and probability, plus this city’s planting-window dates.
What to plant now
TODAY · JULY 19Full-year planting calendar
Each bar is the exact window to take a planting action in Derby, drawn to the day from the local frost dates. The dashed line is today.
Nearby weather stations
3 within 18 km · complete 32°F normalsWhen stations disagree by more than a few days, that spread is real microclimate variation — elevation, water, urban heat. Judge which station best matches your own yard.
Derby planting FAQ
When is the last spring frost in Derby, CT?
Plan for the last spring frost in Derby around April 25 (the date it has a 50% chance of a 32°F freeze). Anything frost-sensitive should go out after it.
When is the first fall frost in Derby, CT?
In Derby, the first 32°F freeze of fall lands around October 17 on average. Time your last harvests and any season-extension cover before it.
What hardiness zone is Derby in?
Derby is in USDA hardiness zone 6b. In zone 6b, winters are moderate — most common vegetables grow well in season.
How long is the growing season in Derby?
There are roughly 175 frost-free days in Derby (a moderate growing season), running from the average last frost around April 25 to the first fall frost near October 17.
When should I plant tomatoes in Derby?
In Derby, start tomato seeds indoors around February 28–March 14, then transplant seedlings outdoors around May 2 once the danger of frost has passed.
Never miss a window in Derby
An email when it’s time to start seeds, transplant, and sow — timed to Derby’s frost dates. Double opt-in, one-click unsubscribe, no spam.
Nearby cities
8 within reach- Ansonia · 2 km
- Shelton · 5 km
- Orange · 7 km
- West Haven · 11 km
- Milford · 11 km
- Trumbull Center · 13 km
- New Haven · 13 km
- Bridgeport · 18 km
Frost dates recorded at ANSONIA 1 NE, 3 km from the city center · 1991–2020 NOAA climate normals · zone from the USDA/PRISM 2023 map. How we compute this.
BlissGarden. "When to Plant in Derby, CT — Frost Dates & Zone 6b." Frost normals: NOAA NCEI U.S. Climate Normals 1991–2020, station USC00060128. Retrieved from https://blissgarden.com/connecticut/derby.