New Haven, Connecticut: planting zone & frost dates
New Haven is in USDA plant hardiness zone 7a, where the average coldest winter night reaches 0 to 5°F (-17.8 to -15.0°C). The typical last spring frost is around Apr 22 and the first fall frost around Oct 20.
Frost dates
| Probability | Last spring frost (32°F) | First fall frost (32°F) |
|---|---|---|
| Safer (10% risk) | May 1 | Oct 11 |
| Typical planning date (30% risk) | Apr 22 | Oct 20 |
| Median (50%) | Apr 17 | Oct 27 |
How to read this: after the spring "10% risk" date, a 32°F frost happens in only about 1 year in 10. In fall, the "10% risk" date is the early end — a frost before it happens about 1 year in 10.
Frost data comes from NOAA station NEW HAVEN TWEED AP, CT (USW00014758), 3.8 mi (6.1 km) from the city center and 26 ft lower than the city center (-8 m). Record used for the 1991–2020 normals: 19 years.
Why your yard may differ from the station: microclimates.
Hardiness zone across New Haven
All 6 ZIP codes covering New Haven are in zone 7a.
Vegetable planting calendar for New Haven
Dates are counted from the 30%-risk frost dates above (last frost Apr 22, first frost Oct 20). Shift a week later in cold spots or low-lying ground.
| Crop | Start indoors | Transplant / plant out | Direct sow | Fall crop sow/plant |
|---|---|---|---|---|
| Tomato | Feb 25 – Mar 11 | Apr 29 – May 13 | — | — |
| Pepper | Feb 11 – Feb 25 | May 6 – May 20 | — | — |
| Lettuce | Mar 11 – Mar 25 | Apr 8 – Apr 29 | Mar 25 – May 6 | Aug 11 – Sep 8 |
| Green Beans | — | — | Apr 29 – Jun 3 | Jul 28 – Aug 11 |
| Sweet Corn | — | — | Apr 29 – May 27 | — |
| Zucchini & Summer Squash | Mar 25 – Apr 1 | Apr 29 – May 13 | Apr 29 – May 20 | Jul 28 – Aug 11 |
| Cucumber | Mar 25 – Apr 1 | May 6 – May 13 | Apr 29 – May 20 | Jul 28 – Aug 11 |
| Carrot | — | — | Apr 1 – May 6 | Jul 28 – Aug 11 |
| Onion | Jan 28 – Feb 11 | Mar 25 – Apr 8 | — | — |
| Potato | — | Mar 25 – Apr 15 | — | — |
| Basil | Mar 11 – Mar 25 | May 6 – May 20 | May 6 – May 27 | — |
| Spinach | — | — | Mar 11 – Apr 8 | Aug 25 – Sep 22 |
| Kale | Feb 25 – Mar 11 | Mar 25 – Apr 15 | Mar 25 – Apr 15 | Aug 11 – Sep 8 |
| Broccoli | Feb 25 – Mar 11 | Apr 8 – Apr 29 | — | Jul 28 – Aug 11 |
| Peas | — | — | Mar 11 – Apr 1 | Aug 11 – Aug 25 |
| Eggplant | Feb 11 – Feb 25 | May 6 – May 20 | — | — |
| Cabbage | Feb 25 – Mar 11 | Mar 25 – Apr 8 | — | Jul 28 – Aug 11 |
| Radish | — | — | Mar 18 – May 6 | Sep 8 – Oct 6 |
| Strawberry | — | Mar 25 – Apr 15 | — | — |
| Beets | — | — | Apr 1 – May 13 | Aug 11 – Aug 25 |
Nearby cities in Connecticut
- Waterbury — zone 6b, last frost May 1, first frost Oct 11
- Bridgeport — zone 7a, last frost Apr 9, first frost Nov 1
- Hartford — zone 6b, last frost Apr 23, first frost Oct 20
- Norwalk — zone 7a, last frost Apr 23, first frost Oct 16
- Danbury — zone 6b, last frost May 6, first frost Oct 7
- Stamford — zone 7a, last frost Apr 23, first frost Oct 16
More: all Connecticut cities · other zone 7a cities: Louisville, KY, Wichita, KS, Cleveland, OH, Lexington, KY, St. Louis, MO, Boise, ID, Amarillo, TX, Providence, RI
New Haven gardening questions
When is the last frost in New Haven, CT?
Plan around Apr 22. At NOAA's NEW Haven Tweed Airport, CT station, 3.8 mi from the city center, there is a 30% chance of a 32°F frost after that date. Half of springs have their last frost by Apr 17, and after May 1 the risk drops to about 1 in 10. A hard freeze (28°F) usually ends earlier, around Apr 4. The 90% and 10% dates are 29 days apart, close to the 36-day median for cities on this site.
When should I plant tomatoes in New Haven, CT?
Start seeds indoors Feb 25 – Mar 11 and set transplants outside Apr 29 – May 13, once nights stay above 50°F and the soil is near 60°F. That leaves 181 days between the 30% frost dates, enough for most varieties including 80–85-day slicers. More: tomato planting dates by zone.
How long is the growing season in New Haven?
About 193 days without a 32°F frost in a typical (median) year. In 9 years out of 10 the season lasts at least 174 days, and in 1 year in 10 it runs 211 days or more. In fall there is a 10% chance of frost by Oct 11 and a 30% chance by Oct 20. That ranks 2nd longest of 7 Connecticut cities on this site.
When should I plant a fall garden in New Haven?
Count back from the first fall frost (Oct 20): transplant broccoli Jul 28 – Aug 11; sow kale Aug 11 – Sep 8; sow lettuce Aug 11 – Sep 8; sow radishes Sep 8 – Oct 6. Hardy crops keep growing through light frosts; the median 28°F hard freeze here is Nov 6. How the math works: succession and fall planting.
Did New Haven's hardiness zone change on the 2023 map?
No. Going by the zone that covers most of the city's land, New Haven is zone 7a on both the 2012 and the 2023 USDA maps (PRISM/OSU ZIP listings). About 42% of U.S. ZIP codes kept their half-zone in 2023. Why the 2023 map is warmer.
How does New Haven compare with Bridgeport, CT?
Both are in zone 7a. The typical last spring frost in New Haven (Apr 22) comes about 13 days later than in Bridgeport, CT (Apr 9), 16 miles away, and the first fall frost is Oct 20 versus Nov 1. The two cities use different NOAA stations.