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Last and first frost dates in Hartford

United States

In Hartford the last spring frost usually comes around 13 April and the first autumn frost around 8 November, which leaves about 209 frost-free days (median of 2016–2025). Tomato seedlings can go into open ground from 19 May to 19 July.

Last spring frostaround 13 April
First autumn frostaround 8 November
Frost-free days209 days
Hardiness zone (USDA-equivalent)official USDA map: 6b

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 Hartford?

The last frost in Hartford usually comes around 13 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 23 March, while corn waits until 29 April. The first autumn frost follows around 8 November, about 209 days later: harvest or cover frost-tender crops before then.

When to sow and plant

CropSow for seedlingsPlant out in a greenhouseOpen ground
Achocha18 February – 31 July30 March – 9 September20 April – 9 September
Ageratumfrom 3 March—from 19 May
Arugula——sow 23 March – 4 October
Basil2 April – 6 September10 May – 14 October31 May – 14 October
Beet——sow 23 March – 9 September
Bell Pepper11 March – 20 May10 May – 19 July31 May – 19 July
Black-eyed Susanfrom 27 January—from 20 April
Bok Choy23 February – 17 September30 March – 22 October20 April – 22 October
Borage——sow 20 April – 14 September
Broad bean——sow 23 March – 31 July
Broccoli——sow 23 March – 24 July
Brussels Sprouts16 January – 21 June2 March – 5 August23 March – 5 August
Busy Lizziefrom 26 January—from 20 April
Cabbage——sow 23 March – 1 July
Calendula——sow from 23 March
Carrot——sow 23 March – 16 August
Cauliflower19 January – 24 July2 March – 4 September23 March – 4 September
Celeriac12 January – 21 May30 March – 6 August20 April – 6 August
Celery12 January – 31 May30 March – 16 August20 April – 16 August
Celosiafrom 15 Marchfrom 29 Aprilfrom 20 May
Chamomile——sow 23 March – 4 September
Chayote10 January – 14 May8 April – 10 August29 April – 10 August
Chickpea——sow 23 March – 21 July
Chicory5 February – 15 August—23 March – 9 September
Chili Pepper11 March – 26 June10 May – 25 August31 May – 25 August
China asterfrom 19 Marchfrom 10 Mayfrom 31 May
Chives——sow 23 March – 26 August
Cilantro——sow 23 March – 5 September
Corn——sow 29 April – 21 July
Corn poppy——sow from 23 March
Cosmosfrom 15 Marchfrom 29 Aprilfrom 20 May
Cucumber12 April – 27 July10 May – 24 August31 May – 24 August
Daikon——sow 23 March – 2 September
Delphiniumfrom 2 January—from 23 March
Dill——sow 23 March – 15 September
Edging lobeliafrom 26 January—from 20 April
Eggplant11 March – 20 May10 May – 19 July31 May – 19 July
Florence fennel13 February – 31 July30 March – 14 September20 April – 14 September
Foxglovefrom 15 December—from 23 March
Garden sorrel——sow 23 March – 3 September
Green Beans——sow 20 May – 29 July
Hollyhock——sow from 23 March
Hyssop——sow 23 March – 27 July
Kale——sow 23 March – 28 August
Kiwano27 March – 3 August28 April – 4 September19 May – 4 September
Kohlrabi——sow 23 March – 7 September
Leek22 December – 12 May2 March – 21 July23 March – 21 July
Lemon balm——sow 23 March – 30 August
Lettuce——sow 23 March – 12 September
Lisianthusfrom 5 Decemberfrom 2 Marchfrom 23 March
Lovage——sow from 23 March
Luffa29 March – 28 May10 May – 9 July31 May – 9 July
Marigoldfrom 16 Februaryfrom 30 Marchfrom 20 April
Marjoram11 March – 15 August—31 May – 14 October
Melon12 April – 14 July10 May – 11 August31 May – 11 August
Microgreens——sow 20 May – 25 October
Moringa30 March – 20 August24 May – 14 October14 June – 14 October
Moss rosefrom 2 February—from 20 April
Mustard greens——sow 23 March – 24 September
Napa cabbage25 February – 25 August30 March – 27 September20 April – 27 September
Nasturtiumfrom 20 Februaryfrom 30 Marchfrom 20 April
Okra29 March – 8 August10 May – 19 September31 May – 19 September
Oregano1 January – 5 August2 March – 4 October23 March – 4 October
Pansyfrom 5 Januaryfrom 2 Marchfrom 23 March
Parsley——sow 23 March – 24 August
Parsnip——sow 23 March – 13 July
Peanut3 April – 4 July10 May – 10 August31 May – 10 August
Peas——sow 23 March – 26 August
Petuniafrom 8 Marchfrom 10 Mayfrom 31 May
Physalis14 March – 1 July28 April – 15 August19 May – 15 August
Pumpkin29 March – 2 June10 May – 14 July31 May – 14 July
Purple coneflowerfrom 30 December—from 23 March
Radish——sow 23 March – 9 October
Sage12 January – 1 August2 March – 19 September23 March – 19 September
Scarlet sagefrom 7 March—from 19 May
Snapdragonfrom 27 Decemberfrom 2 Marchfrom 23 March
Soybean——sow 31 May – 20 August
Spinach——sow 23 March – 14 September
Stevia10 March – 22 June28 April – 10 August19 May – 10 August
Stock——sow from 23 March
Sunflower——sow from 20 May
Sweet alyssum——sow from 23 March
Sweet Corn22 March – 15 August13 April – 6 September4 May – 6 September
Sweet peafrom 19 Januaryfrom 2 Marchfrom 23 March
Sweet William——sow from 23 March
Swiss Chard——sow 23 March – 9 September
Thyme——sow 23 March – 21 July
Tomato7 March – 28 May28 April – 19 July19 May – 19 July
Turnip——sow 23 March – 11 September
Watercress——sow 23 March – 22 September
Watermelon12 April – 2 July10 May – 30 July31 May – 30 July
Zinniafrom 19 Aprilfrom 24 Mayfrom 14 June
Zucchini19 April – 1 August10 May – 22 August31 May – 22 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.

What planting zone is Hartford?

The official USDA map (2023, 1991–2020 data) puts the centre of Hartford (ZIP 06160) in zone 6b. Zone 6b stands for an average coldest night of -5 to 0 °F (-20.6 to -17.8 °C), so perennials hardy to zone 6b or a colder zone should come through a typical winter here.

Check the official USDA map for Hartford: USDA Plant Hardiness Zone Map.

When the soil warms up in Hartford

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 3 days after the last spring frost and 15 °C 36 days after it.

SoilDateAgainst the last spring frost
5 °C10 March34 days earlier
10 °C16 April3 days later
15 °C19 May36 days later
18 °C31 May48 days later

Frost dates near Hartford

Of the nearest cities on our list, the last spring frost ends earliest in New Haven (6 April) and latest in Albany (17 April).

CityDistanceLast spring frostFirst autumn frost
New Haven54 km6 April12 November
Worcester (United States)93 km11 April8 November
Providence106 km11 April8 November
Albany133 km17 April6 November
Boston150 km9 April13 November

Seeds, seedlings and markets in Hartford

Within 15 km of Hartford OpenStreetMap lists 10 garden centres, 1 farm-supply shop, 1 plant nursery, 5 markets and 11 farm shops (collected 20 October 2026). The nearest garden centre to the city centre is General Landscaping, 10 km away.

Places: © OpenStreetMap contributors, ODbL.

What to grow at home in winter in Hartford

Frosts in Hartford usually come from about 8 November to about 13 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 Hartford by month

Average weather in Hartford over 2016–2025: the warmest month is July. Months that average 20 °C or more by day: May–September (20.8–29.5 °C). Nights average below 0 °C in December–March (-5.1–-1 °C). About 1315 mm of rain falls in a year, on 132 days; July is the wettest month (141 mm) and June the driest (82 mm).

MonthDay, °CNight, °CRain, mmRainy days
January3.4-5.11009
February5.4-4.58910
March9.6-111111
April154.112612
May20.89.911413
June26.515.28212
July29.51914114
August28.118.19511
September24.114.51279
October18.18.912611
November10.81.9829
December5.2-2.912211

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 9 October
Crocus9 October – 19 December
Daffodil9 October – 19 December
Garlic9 October – 19 December
Grape hyacinthby 9 October
Helleboreby 9 October
Hyacinth9 October – 19 December
Lilyby 9 October
Ornamental onionby 9 October
Peonyby 9 October
Saffronby 9 October
Snowdropby 9 October
Tulip9 October – 19 December
Wild garlicby 9 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).