USDA zone 7a in Connecticut
USDA plant hardiness zone 7a covers 7 locations across Connecticut (average annual extreme minimum 0 to 5 °F): Deep River Center, CT, Milford, CT, New Haven, CT, New London, CT, Stamford, CT, Stamford, CT, and 1 more. Average last spring frost across this group ranges April 5 (Milford) to May 1 (Weston), and growing seasons run 166–216 days (Weston to Milford) — even within one state, because hardiness sets winter survival, not planting dates. The table below gives every Connecticut location's own frost dates; the printable planting calendar uses New Haven, this group's median-season location.
- USDA zone
- 7a0 to 5 °F
- Last frost range
- Apr 5–May 1avg, 32°F
- First frost range
- Oct 14–Nov 6avg, 32°F
- Growing season range
- 166–216days
Locations in this group
Every location below shares this zone and a nearby weather station, but keeps its own frost dates — find your town for its own numbers, or use the ZIP planner on the home page for an instant personalized answer.
| Location | Also covers | Nearest station | Last frost | First frost | Season (days) |
|---|---|---|---|---|---|
| Deep River Center | — | Meriden Markham Muni Ap | Apr 26 | Oct 16 | 175 |
| Milford | Orange, Bridgeport, Daniels Farm, Westport, Southport, Lordship, +3 more | Bridgeport Sikorsky Mem Ap | Apr 5 | Nov 6 | 216 |
| New Haven * | East Haven, West Haven, Northford, Clinton, Guilford Center, Madison Center, +2 more | New Haven Tweed Ap | Apr 17 | Oct 27 | 193 |
| New London | Fishers Island, Essex, Mystic, Pawcatuck, Old Saybrook Center, Waterford, +3 more | Groton | Apr 8 | Nov 2 | 207 |
| Stamford | Norwalk, Old Hill, Scotts Corners, New Canaan, Cannondale | Stamford 5 N | Apr 17 | Oct 23 | 188 |
| Stamford | Harrison, White Plains, Scarsdale, Briarcliff Manor, Armonk, Greenwich, +12 more | Westchester Co Ap | Apr 12 | Oct 31 | 200 |
| Weston | — | Danbury Muni Ap | May 1 | Oct 14 | 166 |
* New Haven is this group's median-season location — the calendar below is computed from its data.
Data: NOAA NCEI U.S. Climate Normals 1991–2020 (public domain) and USDA Plant Hardiness Zone Map 2023. Planting windows synthesized from U.S. Cooperative Extension guides.
Planting calendar (New Haven, representative)
Computed from New Haven's average frost dates — the median-season location in this Connecticutzone 7a group. hatched = start seeds indoors, solid green = plant out, teal = a fall sowing, and the terracotta dot marks the estimated first harvest. Ranges are extension-guide planning guidance, not guarantees — your own location's dates may run a week or two earlier or later (see the table above).
- Start indoors
- Plant out
- Fall sowing
- First harvest
| Crop | Frost tolerance | Start indoors | Plant out | First harvest | Fall planting | Season fit |
|---|---|---|---|---|---|---|
| Tomato | Tender | Feb 20 – Mar 6 | Apr 24 – May 1 | Jun 23 – Jul 13 | — | matures comfortably |
| Pepper | Very tender | Feb 6 – Feb 20 | May 1 – May 8 | Jun 30 – Jul 30 | — | matures comfortably |
| Cucumber | Tender | Mar 20 – Mar 27 | Apr 24 – May 1 | Jun 13 – Jul 3 | — | matures comfortably |
| Summer squash / zucchini | Tender | — | Apr 24 – May 1 | Jun 8 – Jun 23 | — | matures comfortably |
| Bush bean | Tender | — | Apr 24 – May 1 | Jun 13 – Jun 23 | Aug 28 – Sep 7 | matures comfortably |
| Sweet corn | Tender | — | Apr 17 – May 1 | Jun 16 – Jul 16 | — | matures comfortably |
| Basil | Very tender | Mar 6 – Mar 20 | Apr 24 – May 1 | May 24 – Jun 8 | — | matures comfortably |
| Lettuce | Half-hardy | Mar 6 – Mar 20 | Mar 20 – Apr 3 | May 4 – May 19 | Aug 14 – Aug 29 | matures comfortably |
| Pea | Hardy | — | Mar 6 – Mar 20 | Apr 30 – May 15 | Aug 4 – Aug 19 | matures comfortably |
| Spinach | Hardy | — | Mar 6 – Mar 20 | Apr 15 – Apr 25 | Aug 24 – Sep 3 | matures comfortably |
| Carrot | Half-hardy | — | Mar 27 – Apr 3 | May 26 – Jun 15 | Jul 25 – Aug 14 | matures comfortably |
| Broccoli | Half-hardy | Feb 20 – Mar 6 | Mar 20 – Apr 3 | May 14 – Jun 3 | Jul 30 – Aug 19 | matures comfortably |
Which crops fit this growing season
Using New Haven's own 193-day growing season (32°F, NOAA 1991–2020 median) against each crop's real days-to-maturity range: 12 of 12 crops mature here with comfortable margin. A different location in the table above with a longer or shorter season will get a different mix — the ZIP planner on the home page gives your own.
Frost & freeze dates (New Haven)
From NOAA's 1991–2020 Climate Normals at station USW00014758. The median (p50) is the average date; the 90%-safe column is the date the freeze has passed in about 9 years out of 10 — the conservative date to plant after or harvest before.
| Threshold | Last spring — avg | Last spring — 90%-safe | First fall — avg | First fall — 90%-safe | Season (days) |
|---|---|---|---|---|---|
| 36°F | Apr 30 | May 12 | Oct 15 | Nov 1 | 170 |
| 32°F (freeze) | Apr 17 | May 1 | Oct 27 | Nov 8 | 193 |
| 28°F | Apr 4 | Apr 18 | Nov 6 | Nov 21 | 215 |
| 24°F | Mar 25 | Apr 5 | Nov 19 | Dec 6 | 240 |
Growing degree days
Growing degree days (GDD) accumulate warmth above a base temperature over the year — a better predictor of crop development than the calendar alone. This group's median GDD (base 50°F) across all 7 locations is 3,028; New Haven's own reading is shown below.
| Model | °F·days | Used for |
|---|---|---|
| Base 50°F (warm-season) | 3,028 | standard warm-season base (tomato, corn, beans) |
| Base 40°F (cool-season) | 5,319 | cool-season crops (brassicas, greens) |
Hardiness zone 7a in Connecticut
Zone 7a means an average annual extreme minimum winter temperature of about 0 to 5 °F on the USDA's 2023 map — the number that tells you which perennials, shrubs, and trees reliably survive an average winter here. It does not set your planting dates, which come from the frost calendar above. Connecticut spans 5 hardiness zones in this dataset — see all Connecticut locations for the full range, including zones5b, 6a, 6b, 7b.
Explore zone 7a in other states at zone 7a, or see all USDA hardiness zones.
Frequently asked questions
- What does USDA hardiness zone 7a mean in Connecticut?
- Zone 7a means an average annual extreme minimum winter temperature of 0 to 5 °F — the standard USDA measure of which perennials survive winter. 7 locations in Connecticut fall in this zone. It does not set planting dates; see the frost calendar below for that.
- Where in Connecticut's zone 7a is the growing season longest?
- Milford runs the longest season on this page at about 216 days; Weston is shortest at about 166 days — they share the same hardiness zone, but they sit at different weather stations, so their frost calendars differ.
- When should I plant tomatoes in Connecticut's zone 7a?
- Using New Haven's frost dates (this page's median-season location): start seeds indoors about Feb 20 – Mar 6, then transplant outside about Apr 24 – May 1. Your own location in the table above may differ by a week or two — use the ZIP planner on the home page for your exact station's dates.
- Does every location in Connecticut's zone 7a have the same frost dates?
- No — they do not all share a weather station, so frost dates vary by a week or more across the 7 locations listed (see the table above for each location's own dates).
Sources & method
Frost, freeze, growing-season, and growing-degree-day figures are NOAA NCEI U.S. Climate Normals 1991–2020, one reading per location's own nearest station (see the table above). The hardiness zone is the USDA Plant Hardiness Zone Map 2023, matched to each location's ZIP. Planting windows are computed by counting from the average last and first frost using per-crop offsets synthesized from U.S. Cooperative Extension guides — the full method and citations are on the methodology page.