State guide
Planting zones in Connecticut
Connecticut spans USDA zones 6a to 7b across its 286 ZIP codes, so there is no single zone for the state and anyone who gives you one is rounding. 61% of its ZIP codes are zone 6b; the rest are not.
Your ZIP code
Get the exact answer for your address
Everything above describes Connecticut as a whole. Hardiness zones and freeze dates are published per ZIP code, so yours is exact — enter it and this page will tell you your zone, which NOAA station it comes from and how far away that station is.
Which zone you are in depends where you are
Connecticut covers 4 hardiness zones. A guide that gives the state one zone has picked whichever is largest and rounded everyone else into it — which is fine for the 61% in zone 6b and wrong for the other 39%. Here is the actual split, by ZIP code.
| Zone | ZIP codes | Share | |
|---|---|---|---|
| 6b | 175 | 61% | |
| 7a | 64 | 22% | |
| 6a | 44 | 15% | |
| 7b | 3 | 1% |
Zones are published per ZIP code, so yours is exact even though the state's is not. The hardiness tool will tell you which one you are in.
Your freeze dates
Those are the earliest and latest medians among the 23 stations in Connecticut with an ordinary freeze window — not an average, and not one station standing in for the rest. Half of years freeze later than a station's own median.
Your growing season
NOAA publishes a growing-season length for each station, and across the 23 stations in Connecticut it runs 146–216 days . That figure is published, not computed from the two freeze dates — subtracting one from the other gives the wrong answer wherever a season crosses New Year. Mean summer high (June–August) runs 76–83 °F , below the 90 °F point where cool-season crops reliably bolt.
The ends of each range, named
A range with no station behind it cannot be checked, and Connecticut has too many stations to table them all. So every figure above is reported here with the station standing at each end of it, by name and NOAA ID. No station on this page represents Connecticut — these are its edges, which is a different claim.
| Measure | Earliest / lowest | Station | Latest / highest | Station |
|---|---|---|---|---|
| Last spring freeze | April 5 | Bridgeport Sikorsky Mem AP, CT USW00094702 | May 11 | Falls Village, CT USC00062658 |
| First fall freeze | October 4 | Falls Village, CT USC00062658 | November 6 | Bridgeport Sikorsky Mem AP, CT USW00094702 |
| Growing season | 146 days | Falls Village, CT USC00062658 | 216 days | Bridgeport Sikorsky Mem AP, CT USW00094702 |
| Mean summer high | 76 °F | Norfolk 2 SW, CT USC00065445 | 83 °F | Hartford Bradley INTL AP, CT USW00014740 |
These are medians, not averages — NOAA publishes freeze dates as a probability distribution, and half of years freeze later than the date shown.
When to start seeds in Connecticut
Every spring job for 63 crop dates, counted from this state's own last spring freeze. Each is a range across all 23 stations — the earliest and latest that job falls anywhere in Connecticut — because no one station speaks for a whole state. The ranges are wide on purpose: that width is the state.
| Crop | Job | When | Offset |
|---|---|---|---|
| Green Onions | Start indoors | February 8 – March 16 | 8 weeks before |
| Peppers | Start indoors | February 8 – March 16 | 8 weeks before |
| Broccoli | Start indoors | February 22 – March 30 | 6 weeks before |
| Cabbage | Start indoors | February 22 – March 30 | 6 weeks before |
| Collards | Start indoors | February 22 – March 30 | 6 weeks before |
| Kale | Start indoors | February 22 – March 30 | 6 weeks before |
| Leaf Lettuce | Start indoors | February 22 – March 30 | 6 weeks before |
| Peas | Direct sow | February 22 – March 30 | 6 weeks before |
| Spinach | Direct sow | February 22 – March 30 | 6 weeks before |
| Sweet Potato | Start indoors | February 22 – March 30 | 6 weeks before |
| Tomatoes | Start indoors | February 22 – March 30 | 6 weeks before |
| Bok Choy | Start indoors | March 1 – April 6 | 5 weeks before |
| Kohlrabi | Start indoors | March 1 – April 6 | 5 weeks before |
| Swiss Chard | Start indoors | March 1 – April 6 | 5 weeks before |
| Arugula | Direct sow | March 8 – April 13 | 4 weeks before |
| Baby Salad Greens | Direct sow | March 8 – April 13 | 4 weeks before |
| Beets | Direct sow | March 8 – April 13 | 4 weeks before |
| Green Onions | Direct sow | March 8 – April 13 | 4 weeks before |
| Mustard Greens | Direct sow | March 8 – April 13 | 4 weeks before |
| Okra | Start indoors | March 8 – April 13 | 4 weeks before |
| Radishes | Direct sow | March 8 – April 13 | 4 weeks before |
| Turnips | Direct sow | March 8 – April 13 | 4 weeks before |
| Cabbage | Set out | March 15 – April 20 | 3 weeks before |
| Carrots | Direct sow | March 15 – April 20 | 3 weeks before |
| Collards | Direct sow | March 15 – April 20 | 3 weeks before |
| Collards | Set out | March 15 – April 20 | 3 weeks before |
| Cucumbers | Start indoors | March 15 – April 20 | 3 weeks before |
| Green Onions | Set out | March 15 – April 20 | 3 weeks before |
| Kale | Direct sow | March 15 – April 20 | 3 weeks before |
| Kale | Set out | March 15 – April 20 | 3 weeks before |
| Kohlrabi | Direct sow | March 15 – April 20 | 3 weeks before |
| Kohlrabi | Set out | March 15 – April 20 | 3 weeks before |
| Leaf Lettuce | Direct sow | March 15 – April 20 | 3 weeks before |
| Pumpkins | Start indoors | March 15 – April 20 | 3 weeks before |
| Summer Squash | Start indoors | March 15 – April 20 | 3 weeks before |
| Winter Squash | Start indoors | March 15 – April 20 | 3 weeks before |
| Zucchini | Start indoors | March 15 – April 20 | 3 weeks before |
| Bok Choy | Direct sow | March 22 – April 27 | 2 weeks before |
| Bok Choy | Set out | March 22 – April 27 | 2 weeks before |
| Broccoli | Set out | March 22 – April 27 | 2 weeks before |
| Cilantro | Direct sow | March 22 – April 27 | 2 weeks before |
| Leaf Lettuce | Set out | March 22 – April 27 | 2 weeks before |
| Swiss Chard | Direct sow | March 22 – April 27 | 2 weeks before |
| Swiss Chard | Set out | March 22 – April 27 | 2 weeks before |
| Dill | Direct sow | March 29 – May 4 | 1 week before |
| Bush Beans | Direct sow | April 12 – May 18 | 1 week after |
| Cucumbers | Set out | April 12 – May 18 | 1 week after |
| Pumpkins | Direct sow | April 12 – May 18 | 1 week after |
| Pumpkins | Set out | April 12 – May 18 | 1 week after |
| Summer Squash | Direct sow | April 12 – May 18 | 1 week after |
| Summer Squash | Set out | April 12 – May 18 | 1 week after |
| Sweet Corn | Direct sow | April 12 – May 18 | 1 week after |
| Tomatoes | Set out | April 12 – May 18 | 1 week after |
| Winter Squash | Direct sow | April 12 – May 18 | 1 week after |
| Winter Squash | Set out | April 12 – May 18 | 1 week after |
| Zucchini | Direct sow | April 12 – May 18 | 1 week after |
| Zucchini | Set out | April 12 – May 18 | 1 week after |
| Cucumbers | Direct sow | April 19 – May 25 | 2 weeks after |
| Okra | Direct sow | April 19 – May 25 | 2 weeks after |
| Okra | Set out | April 19 – May 25 | 2 weeks after |
| Peppers | Set out | April 19 – May 25 | 2 weeks after |
| Southern Peas | Direct sow | April 19 – May 25 | 2 weeks after |
| Sweet Potato | Set out | April 19 – May 25 | 2 weeks after |
The week offsets are conventional extension guidance and vary by variety; the freeze dates they are counted from are measured. For a single date rather than a range, run when do I start my seeds? with your own ZIP code.
What survives the winter changes across Connecticut
Of 74 perennial fruits, nuts, berries, vegetables and herbs, 58 come through the winter in zone 7a and only 51 in zone 6a. Winter hardiness runs on the zone alone, so each row below is exact for the ZIP codes in it.
| Zone | ZIPs | Survive | Fail for being too warm |
|---|---|---|---|
| 6a | 44 | 51 of 74 | 0 |
| 6b | 175 | 51 of 74 | 0 |
| 7a | 64 | 58 of 74 | 1 |
| 7b | 3 | 56 of 74 | 3 |
The best zone in Connecticut is 7a, which is not its mildest — 7b is. The count peaks in the middle and falls both ways, because the warm end loses plants to insufficient winter chill and summer heat rather than to cold. Most temperate fruit needs a documented number of hours below about 45 °F to break dormancy and set a crop, so an apple fails in a winter that is too warm; currants and rhubarb cook in the heat that comes with it. See the full list with reasons.
Your own ZIP
Work out your own dates
Each of these takes a ZIP code and answers for that ZIP alone, citing the station it used and how far away it is. There is a ZIP box in the header of every page.
- What survives my winter?
Runs on the hardiness zone, so it answers exactly for your ZIP code rather than for Connecticut as a whole — 74 perennial fruits, berries, vegetables and herbs.
- When do I start my seeds?
Dates every spring job from your own last freeze — sow indoors, set out, direct sow.
- When do I sow the next round?
How often each crop is worth re-sowing, and when the next sowing is due.
- What can I still plant?
Counts the growing days left before your first fall freeze, crop by crop.
Metro areas in Connecticut
Connecticut has no metro pages. Census reorganised its counties into planning regions in 2023, and those do not join the 2020 ZIP-to-county relation these metro pages are built from — so rather than guess at the mapping, there is nothing here. The zone split above and the tools answer every Connecticut ZIP code regardless.
Counties in Connecticut
8 countys here have its own page, listing every ZIP code in it with that ZIP code's exact zone and nearest station. These are the smaller places outside the metro areas above — where most of Connecticut's ZIP codes actually are.
- Hartford County, CT Zones 6a–6b
- Fairfield County, CT Zones 6b–7b
- New Haven County, CT Zones 6b–7a
- Litchfield County, CT Zones 6a–6b
- New London County, CT Zones 6b–7a
- Windham County, CT Zones 6a–6b
- Middlesex County, CT Zones 6b–7a
- Tolland County, CT Zone 6b
Other states to compare
Gear
If you want to act on this
Each link opens an Amazon search rather than a product we picked. We have not tested these and do not rank them — the search is the honest version, and you choose.
- Trunk wrapZone 6a is cold enough that winter sun on a young trunk does more damage than the cold does.
- Row cover and frost clothThe season here closes at the first fall freeze dated above — a cover buys back some of those days at the end.
- MulchFor the perennials nearest their cold limit in zone 6a, where an insulated crown is what decides whether they come back.
As an Amazon Associate we earn from qualifying purchases. That costs you nothing extra, and it buys no influence over anything on this site: the dates come from NOAA normals and the zones from the USDA, and no product affects either.
Sources
Where these numbers come from
The hardiness zone is the USDA 2023 Plant Hardiness Zone Map, published per ZIP code by PRISM at Oregon State. The freeze dates, growing seasons and summer highs are NOAA's 1991–2020 Climate Normals, read from every station in Connecticut. Which ZIP codes are in Connecticut comes from the Census ZIP-to-county relation, since a county's federal code begins with its state's. Nothing here is estimated.
This page names no single station for Connecticut on purpose. Picking one to represent a state sounds reasonable and is not — the same reason the metro pages refuse it, only more so at this size. Instead every range names the station at each end, so you can check both without either one being made to speak for the state.