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Last and first frost dates in Harrisburg

United States

In Harrisburg the last spring frost usually comes around 10 April and the first autumn frost around 11 November, which leaves about 215 frost-free days (median of 2016–2025). Tomato seedlings can go into open ground from 3 May to 22 July.

Last spring frostaround 10 April
First autumn frostaround 11 November
Frost-free days215 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 Harrisburg?

The last frost in Harrisburg usually comes around 10 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 20 March, while corn waits until 17 April. The first autumn frost follows around 11 November, about 215 days later: harvest or cover frost-tender crops before then.

When to sow and plant

CropSow for seedlingsPlant out in a greenhouseOpen ground
Achocha15 February – 3 August27 March – 12 September17 April – 12 September
Ageratumfrom 15 February—from 3 May
Arugula——sow 20 March – 7 October
Basil27 March – 9 September4 May – 17 October25 May – 17 October
Beet——sow 20 March – 12 September
Bell Pepper5 March – 23 May4 May – 22 July25 May – 22 July
Black-eyed Susanfrom 24 January—from 17 April
Bok Choy20 February – 20 September27 March – 25 October17 April – 25 October
Borage——sow 17 April – 17 September
Broad bean——sow 20 March – 3 August
Broccoli——sow 20 March – 27 July
Brussels Sprouts13 January – 24 June27 February – 8 August20 March – 8 August
Busy Lizziefrom 23 January—from 17 April
Cabbage——sow 20 March – 4 July
Calendula——sow from 20 March
Carrot——sow 20 March – 19 August
Cauliflower16 January – 27 July27 February – 7 September20 March – 7 September
Celeriac9 January – 24 May27 March – 9 August17 April – 9 August
Celery9 January – 3 June27 March – 19 August17 April – 19 August
Celosiafrom 1 Marchfrom 15 Aprilfrom 6 May
Chamomile——sow 20 March – 7 September
Chayote29 December – 17 May27 March – 13 August17 April – 13 August
Chickpea——sow 20 March – 24 July
Chicory2 February – 18 August—20 March – 12 September
Chili Pepper5 March – 29 June4 May – 28 August25 May – 28 August
China asterfrom 13 Marchfrom 4 Mayfrom 25 May
Chives——sow 20 March – 29 August
Cilantro——sow 20 March – 8 September
Corn——sow 17 April – 24 July
Corn poppy——sow from 20 March
Cosmosfrom 1 Marchfrom 15 Aprilfrom 6 May
Cucumber6 April – 30 July4 May – 27 August25 May – 27 August
Daikon——sow 20 March – 5 September
Delphiniumfrom 30 December—from 20 March
Dill——sow 20 March – 18 September
Edging lobeliafrom 23 January—from 17 April
Eggplant5 March – 23 May4 May – 22 July25 May – 22 July
Florence fennel10 February – 3 August27 March – 17 September17 April – 17 September
Foxglovefrom 12 December—from 20 March
Garden sorrel——sow 20 March – 6 September
Green Beans——sow 6 May – 1 August
Hollyhock——sow from 20 March
Hyssop——sow 20 March – 30 July
Kale——sow 20 March – 31 August
Kiwano11 March – 6 August12 April – 7 September3 May – 7 September
Kohlrabi——sow 20 March – 10 September
Leek19 December – 15 May27 February – 24 July20 March – 24 July
Lemon balm——sow 20 March – 2 September
Lettuce——sow 20 March – 15 September
Lisianthusfrom 2 Decemberfrom 27 Februaryfrom 20 March
Lovage——sow from 20 March
Luffa23 March – 31 May4 May – 12 July25 May – 12 July
Marigoldfrom 13 Februaryfrom 27 Marchfrom 17 April
Marjoram5 March – 18 August—25 May – 17 October
Melon6 April – 17 July4 May – 14 August25 May – 14 August
Microgreens——sow 6 May – 28 October
Moringa16 March – 23 August10 May – 17 October31 May – 17 October
Moss rosefrom 30 January—from 17 April
Mustard greens——sow 20 March – 27 September
Napa cabbage22 February – 28 August27 March – 30 September17 April – 30 September
Nasturtiumfrom 17 Februaryfrom 27 Marchfrom 17 April
Okra23 March – 11 August4 May – 22 September25 May – 22 September
Oregano29 December – 8 August27 February – 7 October20 March – 7 October
Pansyfrom 2 Januaryfrom 27 Februaryfrom 20 March
Parsley——sow 20 March – 27 August
Parsnip——sow 20 March – 16 July
Peanut28 March – 7 July4 May – 13 August25 May – 13 August
Peas——sow 20 March – 29 August
Petuniafrom 2 Marchfrom 4 Mayfrom 25 May
Physalis26 February – 4 July12 April – 18 August3 May – 18 August
Pumpkin23 March – 5 June4 May – 17 July25 May – 17 July
Purple coneflowerfrom 27 December—from 20 March
Radish——sow 20 March – 12 October
Sage9 January – 4 August27 February – 22 September20 March – 22 September
Scarlet sagefrom 19 February—from 3 May
Snapdragonfrom 24 Decemberfrom 27 Februaryfrom 20 March
Soybean——sow 25 May – 23 August
Spinach——sow 20 March – 17 September
Stevia22 February – 25 June12 April – 13 August3 May – 13 August
Stock——sow from 20 March
Sunflower——sow from 6 May
Sweet alyssum——sow from 20 March
Sweet Corn5 March – 18 August27 March – 9 September17 April – 9 September
Sweet peafrom 16 Januaryfrom 27 Februaryfrom 20 March
Sweet William——sow from 20 March
Swiss Chard——sow 20 March – 12 September
Thyme——sow 20 March – 24 July
Tomato19 February – 31 May12 April – 22 July3 May – 22 July
Turnip——sow 20 March – 14 September
Watercress——sow 20 March – 25 September
Watermelon6 April – 5 July4 May – 2 August25 May – 2 August
Zinniafrom 5 Aprilfrom 10 Mayfrom 31 May
Zucchini13 April – 4 August4 May – 25 August25 May – 25 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 Harrisburg

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 16 days before the last spring frost and 15 °C 23 days after it.

SoilDateAgainst the last spring frost
5 °C6 March35 days earlier
10 °C25 March16 days earlier
15 °C3 May23 days later
18 °C25 May45 days later

Frost dates near Harrisburg

Of the nearest cities on our list, the last spring frost ends earliest in Annapolis (29 March) and latest in Allentown (15 April).

CityDistanceLast spring frostFirst autumn frost
Hagerstown103 km4 April11 November
Baltimore111 km31 March22 November
Allentown124 km15 April3 November
Annapolis148 km29 March19 November
Philadelphia150 km3 April11 November

Seeds, seedlings and markets in Harrisburg

Within 15 km of Harrisburg OpenStreetMap lists 4 garden centres, 4 markets and 3 farm shops (collected 28 October 2026). The nearest garden centre to the city centre is The Plant Witch, 1 km away.

Places: © OpenStreetMap contributors, ODbL.

What to grow at home in winter in Harrisburg

Frosts in Harrisburg usually come from about 11 November to about 10 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 Harrisburg by month

Average weather in Harrisburg over 2016–2025: the warmest month is July. Months that average 20 °C or more by day: May–September (22.2–31 °C). Months that average 30 °C or more by day: July (31 °C). Nights average below 0 °C in January (-3.5 °C), February (-2.3 °C) and December (-1.3 °C). About 1156 mm of rain falls in a year, on 130 days; July is the wettest month (126 mm) and November the driest (70 mm).

MonthDay, °CNight, °CRain, mmRainy days
January4.2-3.5799
February7.4-2.3919
March11.918611
April17.5610012
May22.211.412115
June27.616.59713
July3120.112613
August291911012
September25.415.711110
October19.39.7799
November11.82.9707
December6.3-1.38610

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 12 October
Crocus12 October – end of December
Daffodil12 October – end of December
Garlic12 October – end of December
Grape hyacinthby 12 October
Helleboreby 12 October
Hyacinth12 October – end of December
Lilyby 12 October
Ornamental onionby 12 October
Peonyby 12 October
Saffronby 12 October
Snowdropby 12 October
Tulip12 October – end of December
Wild garlicby 12 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).