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Last and first frost dates in Siena

Italy

In Siena the last spring frost usually comes around 16 March and the first autumn frost around 27 November, which leaves about 256 frost-free days (median of 2016–2025). Tomato seedlings can go into open ground from 22 April to 7 August.

Last spring frostaround 16 March
First autumn frostaround 27 November
Frost-free days256 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 Siena?

The last frost in Siena usually comes around 16 March: 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 February, while corn waits until 2 April. The first autumn frost follows around 27 November, about 256 days later: harvest or cover frost-tender crops before then.

When to sow and plant

CropSow for seedlingsPlant out in a greenhouseOpen ground
Achocha21 January – 19 August2 March – 28 September23 March – 28 September
Ageratumfrom 4 February—from 22 April
Arugula——sow 23 February – 23 October
Basil28 March – 25 September5 May – 2 November26 May – 2 November
Beet——sow 23 February – 28 September
Bell Pepper6 March – 8 June5 May – 7 August26 May – 7 August
Black-eyed Susanfrom 30 December—from 23 March
Bok Choy26 January – 6 October2 March – 10 November23 March – 10 November
Borage——sow 23 March – 3 October
Broad bean——sow 23 February – 19 August
Broccoli——sow 23 February – 12 August
Brussels Sprouts19 December – 10 July2 February – 24 August23 February – 24 August
Busy Lizziefrom 29 December—from 23 March
Cabbage——sow 23 February – 20 July
Calendula——sow from 23 February
Carrot——sow 23 February – 4 September
Cauliflower22 December – 12 August2 February – 23 September23 February – 23 September
Celeriac15 December – 9 June2 March – 25 August23 March – 25 August
Celery15 December – 19 June2 March – 4 September23 March – 4 September
Celosiafrom 26 Februaryfrom 12 Aprilfrom 3 May
Chamomile——sow 23 February – 23 September
Chayote14 December – 2 June12 March – 29 August2 April – 29 August
Chickpea——sow 23 February – 9 August
Chicory8 January – 3 September—23 February – 28 September
Chili Pepper6 March – 15 July5 May – 13 September26 May – 13 September
China asterfrom 14 Marchfrom 5 Mayfrom 26 May
Chives——sow 23 February – 14 September
Cilantro——sow 23 February – 24 September
Corn——sow 2 April – 9 August
Corn poppy——sow from 23 February
Cosmosfrom 26 Februaryfrom 12 Aprilfrom 3 May
Cucumber7 April – 15 August5 May – 12 September26 May – 12 September
Daikon——sow 23 February – 21 September
Delphiniumfrom 5 December—from 23 February
Dill——sow 23 February – 4 October
Edging lobeliafrom 29 December—from 23 March
Eggplant6 March – 8 June5 May – 7 August26 May – 7 August
Florence fennel16 January – 19 August2 March – 3 October23 March – 3 October
Foxglovefrom 17 November—from 23 February
Garden sorrel——sow 23 February – 22 September
Green Beans——sow 3 May – 17 August
Hollyhock——sow from 23 February
Hyssop——sow 23 February – 15 August
Kale——sow 23 February – 16 September
Kiwano28 February – 22 August1 April – 23 September22 April – 23 September
Kohlrabi——sow 23 February – 26 September
Leek24 November – 31 May2 February – 9 August23 February – 9 August
Lemon balm——sow 23 February – 18 September
Lettuce——sow 23 February – 1 October
Lisianthusfrom 7 Novemberfrom 2 Februaryfrom 23 February
Lovage——sow from 23 February
Luffa24 March – 16 June5 May – 28 July26 May – 28 July
Marigoldfrom 19 Januaryfrom 2 Marchfrom 23 March
Marjoram6 March – 3 September—26 May – 2 November
Melon7 April – 2 August5 May – 30 August26 May – 30 August
Microgreens——sow 3 May – 13 November
Moringa16 March – 8 September10 May – 2 November31 May – 2 November
Moss rosefrom 5 January—from 23 March
Mustard greens——sow 23 February – 13 October
Napa cabbage28 January – 13 September2 March – 16 October23 March – 16 October
Nasturtiumfrom 23 Januaryfrom 2 Marchfrom 23 March
Okra24 March – 27 August5 May – 8 October26 May – 8 October
Oregano4 December – 24 August2 February – 23 October23 February – 23 October
Pansyfrom 8 Decemberfrom 2 Februaryfrom 23 February
Parsley——sow 23 February – 12 September
Parsnip——sow 23 February – 1 August
Peanut29 March – 23 July5 May – 29 August26 May – 29 August
Peas——sow 23 February – 14 September
Petuniafrom 3 Marchfrom 5 Mayfrom 26 May
Physalis15 February – 20 July1 April – 3 September22 April – 3 September
Pumpkin24 March – 21 June5 May – 2 August26 May – 2 August
Purple coneflowerfrom 2 December—from 23 February
Radish——sow 23 February – 28 October
Sage15 December – 20 August2 February – 8 October23 February – 8 October
Scarlet sagefrom 8 February—from 22 April
Snapdragonfrom 29 Novemberfrom 2 Februaryfrom 23 February
Soybean——sow 26 May – 8 September
Spinach——sow 23 February – 3 October
Stevia11 February – 11 July1 April – 29 August22 April – 29 August
Stock——sow from 23 February
Sunflower——sow from 3 May
Sweet alyssum——sow from 23 February
Sweet Corn27 February – 3 September21 March – 25 September11 April – 25 September
Sweet peafrom 22 Decemberfrom 2 Februaryfrom 23 February
Sweet William——sow from 23 February
Swiss Chard——sow 23 February – 28 September
Thyme——sow 23 February – 9 August
Tomato8 February – 16 June1 April – 7 August22 April – 7 August
Turnip——sow 23 February – 30 September
Watercress——sow 23 February – 11 October
Watermelon7 April – 21 July5 May – 18 August26 May – 18 August
Zinniafrom 5 Aprilfrom 10 Mayfrom 31 May
Zucchini14 April – 20 August5 May – 10 September26 May – 10 September

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 Siena

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 1 day before the last spring frost and 15 °C 37 days after it.

SoilDateAgainst the last spring frost
5 °Calready in the first week of January—
10 °C15 March1 day earlier
15 °C22 April37 days later
18 °C26 May71 days later

Frost dates near Siena

Of the nearest cities on our list, the last spring frost ends earliest in Livorno (22 January) and latest in Pisa (9 April).

CityDistanceLast spring frostFirst autumn frost
Arezzo47 km6 April21 November
Florence50 km23 March27 November
Livorno84 km22 January—
Pisa87 km9 April18 November
Perugia89 km7 April25 November

Seeds, seedlings and markets in Siena

Within 15 km of Siena OpenStreetMap lists 3 garden centres, 2 farm-supply shops, 4 plant nurseries, 6 markets and 1 farm shop (collected 27 October 2026). The nearest garden centre to the city centre is Brico & Garden, 3 km away.

Places: © OpenStreetMap contributors, ODbL.

What to grow at home in winter in Siena

Frosts in Siena usually come from about 27 November to about 16 March. 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 Siena by month

Average weather in Siena over 2016–2025: the warmest month is July. Months that average 20 °C or more by day: May–October (21.4–32.5 °C). Months that average 30 °C or more by day: July (32.5 °C) and August (32.4 °C). No month averages below 0 °C at night; the coldest nights, in January, average 1.5 °C. About 799 mm of rain falls in a year, on 103 days; November is the wettest month (107 mm) and July the driest (22 mm).

MonthDay, °CNight, °CRain, mmRainy days
January10.51.5479
February12.82.8759
March15.14.1669
April18.96.9569
May22.5119112
June29.116417
July32.518.8224
August32.418.9356
September26.514.8778
October21.410.9978
November15.26.210712
December11.52.88510

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 28 October
Crocusby 28 October
Daffodilby 28 October
Garlic28 October – end of December
Grape hyacinthby 28 October
Helleboreby 28 October
Hyacinthby 28 October
Lilyby 28 October
Ornamental onionby 28 October
Peonyby 28 October
Saffronby 28 October
Snowdropby 28 October
Tulipby 28 October
Wild garlicby 28 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).