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Last and first frost dates in New Haven

United States

In New Haven the last spring frost usually comes around 6 April and the first autumn frost around 12 November, which leaves about 220 frost-free days (median of 2016–2025). Tomato seedlings can go into open ground from 17 May to 23 July.

Last spring frostaround 6 April
First autumn frostaround 12 November
Frost-free days220 days

Median of 2016–2025 for the 25 km grid cell of the city: the last day at or below 0 °C in spring and the first in autumn (ERA5 reanalysis via Open-Meteo). In a cold year a frost can come a week or two later — Greenly warns 48 hours ahead.

When is the last frost in New Haven?

The last frost in New Haven usually comes around 6 April: that is the median of 2016–2025, so in about half of those years the last night at or below 0 °C came later. Hardy crops start before it and frost-tender ones only after it: in the table below arugula can go into open ground from 16 March, while corn waits until 20 April. The first autumn frost follows around 12 November, about 220 days later: harvest or cover frost-tender crops before then.

When to sow and plant

CropSow for seedlingsPlant out in a greenhouseOpen ground
Achocha12 February – 4 August24 March – 13 September14 April – 13 September
Ageratumfrom 1 March—from 17 May
Arugula——sow 16 March – 8 October
Basil28 March – 10 September5 May – 18 October26 May – 18 October
Beet——sow 16 March – 13 September
Bell Pepper6 March – 24 May5 May – 23 July26 May – 23 July
Black-eyed Susanfrom 21 January—from 14 April
Bok Choy17 February – 21 September24 March – 26 October14 April – 26 October
Borage——sow 13 April – 18 September
Broad bean——sow 16 March – 4 August
Broccoli——sow 16 March – 28 July
Brussels Sprouts9 January – 25 June23 February – 9 August16 March – 9 August
Busy Lizziefrom 19 January—from 13 April
Cabbage——sow 16 March – 5 July
Calendula——sow from 16 March
Carrot——sow 16 March – 20 August
Cauliflower12 January – 28 July23 February – 8 September16 March – 8 September
Celeriac6 January – 25 May24 March – 10 August14 April – 10 August
Celery6 January – 4 June24 March – 20 August14 April – 20 August
Celosiafrom 14 Marchfrom 28 Aprilfrom 19 May
Chamomile——sow 16 March – 8 September
Chayote1 January – 18 May30 March – 14 August20 April – 14 August
Chickpea——sow 16 March – 25 July
Chicory29 January – 19 August—16 March – 13 September
Chili Pepper6 March – 30 June5 May – 29 August26 May – 29 August
China asterfrom 14 Marchfrom 5 Mayfrom 26 May
Chives——sow 16 March – 30 August
Cilantro——sow 16 March – 9 September
Corn——sow 20 April – 25 July
Corn poppy——sow from 16 March
Cosmosfrom 14 Marchfrom 28 Aprilfrom 19 May
Cucumber7 April – 31 July5 May – 28 August26 May – 28 August
Daikon——sow 16 March – 6 September
Delphiniumfrom 26 December—from 16 March
Dill——sow 16 March – 19 September
Edging lobeliafrom 20 January—from 14 April
Eggplant6 March – 24 May5 May – 23 July26 May – 23 July
Florence fennel7 February – 4 August24 March – 18 September14 April – 18 September
Foxglovefrom 8 December—from 16 March
Garden sorrel——sow 16 March – 7 September
Green Beans——sow 19 May – 2 August
Hollyhock——sow from 16 March
Hyssop——sow 16 March – 31 July
Kale——sow 16 March – 1 September
Kiwano25 March – 7 August26 April – 8 September17 May – 8 September
Kohlrabi——sow 16 March – 11 September
Leek15 December – 16 May23 February – 25 July16 March – 25 July
Lemon balm——sow 16 March – 3 September
Lettuce——sow 16 March – 16 September
Lisianthusfrom 28 Novemberfrom 23 Februaryfrom 16 March
Lovage——sow from 16 March
Luffa24 March – 1 June5 May – 13 July26 May – 13 July
Marigoldfrom 10 Februaryfrom 24 Marchfrom 14 April
Marjoram6 March – 19 August—26 May – 18 October
Melon7 April – 18 July5 May – 15 August26 May – 15 August
Microgreens——sow 19 May – 29 October
Moringa24 March – 24 August18 May – 18 October8 June – 18 October
Moss rosefrom 26 January—from 13 April
Mustard greens——sow 16 March – 28 September
Napa cabbage19 February – 29 August24 March – 1 October14 April – 1 October
Nasturtiumfrom 14 Februaryfrom 24 Marchfrom 14 April
Okra24 March – 12 August5 May – 23 September26 May – 23 September
Oregano25 December – 9 August23 February – 8 October16 March – 8 October
Pansyfrom 29 Decemberfrom 23 Februaryfrom 16 March
Parsley——sow 16 March – 28 August
Parsnip——sow 16 March – 17 July
Peanut29 March – 8 July5 May – 14 August26 May – 14 August
Peas——sow 16 March – 30 August
Petuniafrom 3 Marchfrom 5 Mayfrom 26 May
Physalis12 March – 5 July26 April – 19 August17 May – 19 August
Pumpkin24 March – 6 June5 May – 18 July26 May – 18 July
Purple coneflowerfrom 23 December—from 16 March
Radish——sow 16 March – 13 October
Sage5 January – 5 August23 February – 23 September16 March – 23 September
Scarlet sagefrom 5 March—from 17 May
Snapdragonfrom 20 Decemberfrom 23 Februaryfrom 16 March
Soybean——sow 26 May – 24 August
Spinach——sow 16 March – 18 September
Stevia8 March – 26 June26 April – 14 August17 May – 14 August
Stock——sow from 16 March
Sunflower——sow from 19 May
Sweet alyssum——sow from 16 March
Sweet Corn17 March – 19 August8 April – 10 September29 April – 10 September
Sweet peafrom 12 Januaryfrom 23 Februaryfrom 16 March
Sweet William——sow from 16 March
Swiss Chard——sow 16 March – 13 September
Thyme——sow 16 March – 25 July
Tomato5 March – 1 June26 April – 23 July17 May – 23 July
Turnip——sow 16 March – 15 September
Watercress——sow 16 March – 26 September
Watermelon7 April – 6 July5 May – 3 August26 May – 3 August
Zinniafrom 13 Aprilfrom 18 Mayfrom 8 June
Zucchini14 April – 5 August5 May – 26 August26 May – 26 August

Planting out: a week after the last frost once the soil is warm enough for the crop; frost-hardy crops three weeks before it; an unheated greenhouse three weeks earlier. Seedlings are sown so they are ready on that day. Each window starts on the Greenly calendar date and ends on the last day that still leaves the crop’s days to harvest (from its card) before the average first autumn frost, plus six weeks of picking for crops harvested over weeks (tomatoes, peppers, aubergines, cucumbers, courgettes, pumpkins, watermelons, beans) — our rule; earlier in the window is safer.

When the soil warms up in New Haven

The day the top 7 cm of soil first averages each temperature over a week, median of 2016–2025 (ERA5 via Open-Meteo). The soil reaches 10 °C 8 days after the last spring frost and 15 °C 41 days after it.

SoilDateAgainst the last spring frost
5 °C1 March36 days earlier
10 °C14 April8 days later
15 °C17 May41 days later
18 °C26 May50 days later

Frost dates near New Haven

Of the nearest cities on our list, the last spring frost ends earliest in New York (3 April) and latest in Albany (17 April).

CityDistanceLast spring frostFirst autumn frost
Hartford54 km13 April8 November
New York113 km3 April20 November
Providence138 km11 April8 November
Worcester (United States)141 km11 April8 November
Albany164 km17 April6 November

Seeds, seedlings and markets in New Haven

Within 15 km of New Haven OpenStreetMap lists 5 garden centres, 1 plant nursery, 1 market and 3 farm shops (collected 28 October 2026). The nearest garden centre to the city centre is Shoreline Nursery, 7 km away.

Places: © OpenStreetMap contributors, ODbL.

What to grow at home in winter in New Haven

Frosts in New Haven usually come from about 12 November to about 6 April. These plants have indoor care in their Greenly cards and are harvested quickly, so they can be sown on a windowsill in winter.

Weather in New Haven by month

Average weather in New Haven over 2016–2025: the warmest month is July. Months that average 20 °C or more by day: June–September (23.6–28.2 °C). Nights average below 0 °C in January (-3.4 °C), February (-2.8 °C) and December (-1.1 °C). About 1328 mm of rain falls in a year, on 130 days; December is the wettest month (131 mm) and June the driest (81 mm).

MonthDay, °CNight, °CRain, mmRainy days
January4-3.410610
February5.7-2.89910
March9.30.311311
April14.25.112712
May19.410.511713
June24.915.98110
July28.220.112112
August27.119.210312
September23.615.811810
October18.210.412511
November11.53.5878
December6-1.113111

Average of the daily highs and lows, rain per month and days with at least 1 mm (ERA5 via Open-Meteo, the same grid cell as the frost dates).

Planted in autumn

CropWhen to plant
Bearded Irisby 13 October
Crocus13 October – end of December
Daffodil13 October – end of December
Garlic13 October – end of December
Grape hyacinthby 13 October
Helleboreby 13 October
Hyacinth13 October – end of December
Lilyby 13 October
Ornamental onionby 13 October
Peonyby 13 October
Saffronby 13 October
Snowdropby 13 October
Tulip13 October – end of December
Wild garlicby 13 October

From a month before the first autumn frost, so the roots grow before winter, to the late-planting limit on each crop’s page (about two weeks before the ground freezes, by ten years of weather).