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Last and first frost dates in Tucson

United States

In Tucson the last spring frost usually comes around 6 February and the first autumn frost around 18 December, which leaves about 315 frost-free days (median of 2016–2025). Tomato seedlings can go into open ground from 14 February to 28 August.

Last spring frostaround 6 February
First autumn frostaround 18 December
Frost-free days315 days
Hardiness zone (USDA-equivalent)official USDA map: 9b

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 Tucson?

The last frost in Tucson usually comes around 6 February: 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 January, while corn waits until 13 February. The first autumn frost follows around 18 December, about 315 days later: harvest or cover frost-tender crops before then.

When to sow and plant

CropSow for seedlingsPlant out in a greenhouseOpen ground
Achocha14 December – 9 September23 January – 19 October13 February – 19 October
Ageratumfrom 29 November—from 14 February
Arugula——sow 16 January – 13 November
Basil7 January – 16 October14 February – 23 November7 March – 23 November
Beet——sow 16 January – 19 October
Bell Pepper16 December – 29 June14 February – 28 August7 March – 28 August
Black-eyed Susanfrom 22 November—from 13 February
Bok Choy19 December – 27 October23 January – 1 December13 February – 1 December
Borage——sow 13 February – 24 October
Broad bean——sow 16 January – 9 September
Broccoli——sow 16 January – 2 September
Brussels Sprouts11 November – 31 July26 December – 14 September16 January – 14 September
Busy Lizziefrom 21 November—from 13 February
Cabbage——sow 16 January – 10 August
Calendula——sow from 16 January
Carrot——sow 16 January – 25 September
Cauliflower14 November – 2 September26 December – 14 October16 January – 14 October
Celeriac7 November – 30 June23 January – 15 September13 February – 15 September
Celery7 November – 10 July23 January – 25 September13 February – 25 September
Celosiafrom 14 Decemberfrom 28 Januaryfrom 18 February
Chamomile——sow 16 January – 14 October
Chayote27 October – 23 June23 January – 19 September13 February – 19 September
Chickpea——sow 16 January – 30 August
Chicory1 December – 24 September—16 January – 19 October
Chili Pepper16 December – 5 August14 February – 4 October7 March – 4 October
China asterfrom 24 Decemberfrom 14 Februaryfrom 7 March
Chives——sow 16 January – 5 October
Cilantro——sow 16 January – 15 October
Corn——sow 13 February – 30 August
Corn poppy——sow from 16 January
Cosmosfrom 14 Decemberfrom 28 Januaryfrom 18 February
Cucumber17 January – 5 September14 February – 3 October7 March – 3 October
Daikon——sow 16 January – 12 October
Delphiniumfrom 28 October—from 16 January
Dill——sow 16 January – 25 October
Edging lobeliafrom 21 November—from 13 February
Eggplant16 December – 29 June14 February – 28 August7 March – 28 August
Florence fennel9 December – 9 September23 January – 24 October13 February – 24 October
Foxglovefrom 10 October—from 16 January
Garden sorrel——sow 16 January – 13 October
Green Beans——sow 18 February – 7 September
Hollyhock——sow from 16 January
Hyssop——sow 16 January – 5 September
Kale——sow 16 January – 7 October
Kiwano23 December – 12 September24 January – 14 October14 February – 14 October
Kohlrabi——sow 16 January – 17 October
Leek17 October – 21 June26 December – 30 August16 January – 30 August
Lemon balm——sow 16 January – 9 October
Lettuce——sow 16 January – 22 October
Lisianthusfrom 30 Septemberfrom 26 Decemberfrom 16 January
Lovage——sow from 16 January
Luffa3 January – 7 July14 February – 18 August7 March – 18 August
Marigoldfrom 12 Decemberfrom 23 Januaryfrom 13 February
Marjoram16 December – 24 September—7 March – 23 November
Melon17 January – 23 August14 February – 20 September7 March – 20 September
Microgreens——sow 18 February – 4 December
Moringa28 December – 29 September21 February – 23 November14 March – 23 November
Moss rosefrom 28 November—from 13 February
Mustard greens——sow 16 January – 3 November
Napa cabbage21 December – 4 October23 January – 6 November13 February – 6 November
Nasturtiumfrom 16 Decemberfrom 23 Januaryfrom 13 February
Okra3 January – 17 September14 February – 29 October7 March – 29 October
Oregano27 October – 14 September26 December – 13 November16 January – 13 November
Pansyfrom 31 Octoberfrom 26 Decemberfrom 16 January
Parsley——sow 16 January – 3 October
Parsnip——sow 16 January – 22 August
Peanut8 January – 13 August14 February – 19 September7 March – 19 September
Peas——sow 16 January – 5 October
Petuniafrom 13 Decemberfrom 14 Februaryfrom 7 March
Physalis10 December – 10 August24 January – 24 September14 February – 24 September
Pumpkin3 January – 12 July14 February – 23 August7 March – 23 August
Purple coneflowerfrom 25 October—from 16 January
Radish——sow 16 January – 18 November
Sage7 November – 10 September26 December – 29 October16 January – 29 October
Scarlet sagefrom 3 December—from 14 February
Snapdragonfrom 22 Octoberfrom 26 Decemberfrom 16 January
Soybean——sow 7 March – 29 September
Spinach——sow 16 January – 24 October
Stevia6 December – 1 August24 January – 19 September14 February – 19 September
Stock——sow from 16 January
Sunflower——sow from 18 February
Sweet alyssum——sow from 16 January
Sweet Corn1 January – 24 September23 January – 16 October13 February – 16 October
Sweet peafrom 14 Novemberfrom 26 Decemberfrom 16 January
Sweet William——sow from 16 January
Swiss Chard——sow 16 January – 19 October
Thyme——sow 16 January – 30 August
Tomato3 December – 7 July24 January – 28 August14 February – 28 August
Turnip——sow 16 January – 21 October
Watercress——sow 16 January – 1 November
Watermelon17 January – 11 August14 February – 8 September7 March – 8 September
Zinniafrom 17 Januaryfrom 21 Februaryfrom 14 March
Zucchini24 January – 10 September14 February – 1 October7 March – 1 October

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 Tucson?

The official USDA map (2023, 1991–2020 data) puts the centre of Tucson (ZIP 85726) in zone 9b. Zone 9b stands for an average coldest night of 25 to 30 °F (-3.9 to -1.1 °C), so perennials hardy to zone 9b or a colder zone should come through a typical winter here.

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

When the soil warms up in Tucson

The day the top 7 cm of soil first averages each temperature over a week, median of 2016–2025 (ERA5 via Open-Meteo).

SoilDateAgainst the last spring frost
5 °Calready in the first week of January—
10 °Calready in the first week of January—
15 °C14 February8 days later
18 °C7 March29 days later

Frost dates near Tucson

Of the nearest cities on our list, the last spring frost ends earliest in Phoenix (4 February) and latest in Flagstaff (5 May).

CityDistanceLast spring frostFirst autumn frost
Phoenix173 km4 February29 December
Flagstaff335 km5 May21 October
Yuma345 km——
Hermosillo350 km——
Las Cruces390 km28 February24 November

Seeds, seedlings and markets in Tucson

Within 15 km of Tucson OpenStreetMap lists 10 garden centres, 1 farm-supply shop and 5 markets (collected 20 October 2026). The nearest garden centre to the city centre is Casita Verde, 4 km away.

Places: © OpenStreetMap contributors, ODbL.

What to grow at home in winter in Tucson

Frosts in Tucson usually come from about 18 December to about 6 February. 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 Tucson by month

Average weather in Tucson over 2016–2025: the warmest month is June. Months that average 20 °C or more by day: February–November (20.9–38.5 °C). Months that average 30 °C or more by day: May–October (30.7–38.5 °C). No month averages below 0 °C at night; the coldest nights, in January, average 4.5 °C. About 349 mm of rain falls in a year, on 47 days; July is the wettest month (59 mm) and May the driest (3 mm).

MonthDay, °CNight, °CRain, mmRainy days
January17.94.5364
February20.96295
March24.38.9224
April29.41351
May33.117.231
June38.523.2101
July3825.7598
August36.924.6467
September3521.8536
October30.715.9283
November24.410233
December19.66.3354

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 18 November
Crocusby 18 November
Daffodilby 18 November
Garlicby 18 November
Grape hyacinthby 18 November
Helleboreby 18 November
Hyacinthby 18 November
Lilyby 18 November
Ornamental onionby 18 November
Peonyby 18 November
Saffronby 18 November
Snowdropby 18 November
Tulipby 18 November
Wild garlicby 18 November

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).