Greenly Garden
Get the app
EN

Last and first frost dates in Okayama

Japan

In Okayama the last spring frost usually comes around 20 March and the first autumn frost around 15 December, which leaves about 270 frost-free days (median of 2016–2025). Tomato seedlings can go into open ground from 21 April to 25 August.

Last spring frostaround 20 March
First autumn frostaround 15 December
Frost-free days270 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 Okayama?

The last frost in Okayama usually comes around 20 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 27 February, while corn waits until 30 March. The first autumn frost follows around 15 December, about 270 days later: harvest or cover frost-tender crops before then.

When to sow and plant

CropSow for seedlingsPlant out in a greenhouseOpen ground
Achocha25 January – 6 September6 March – 16 October27 March – 16 October
Ageratumfrom 3 February—from 21 April
Arugula——sow 27 February – 10 November
Basil16 March – 13 October23 April – 20 November14 May – 20 November
Beet——sow 27 February – 16 October
Bell Pepper22 February – 26 June23 April – 25 August14 May – 25 August
Black-eyed Susanfrom 3 January—from 27 March
Bok Choy30 January – 24 October6 March – 28 November27 March – 28 November
Borage——sow 27 March – 21 October
Broad bean——sow 27 February – 6 September
Broccoli——sow 27 February – 30 August
Brussels Sprouts23 December – 28 July6 February – 11 September27 February – 11 September
Busy Lizziefrom 2 January—from 27 March
Cabbage——sow 27 February – 7 August
Calendula——sow from 27 February
Carrot——sow 27 February – 22 September
Cauliflower26 December – 30 August6 February – 11 October27 February – 11 October
Celeriac19 December – 27 June6 March – 12 September27 March – 12 September
Celery19 December – 7 July6 March – 22 September27 March – 22 September
Celosiafrom 17 Februaryfrom 3 Aprilfrom 24 April
Chamomile——sow 27 February – 11 October
Chayote11 December – 20 June9 March – 16 September30 March – 16 September
Chickpea——sow 27 February – 27 August
Chicory12 January – 21 September—27 February – 16 October
Chili Pepper22 February – 2 August23 April – 1 October14 May – 1 October
China asterfrom 2 Marchfrom 23 Aprilfrom 14 May
Chives——sow 27 February – 2 October
Cilantro——sow 27 February – 12 October
Corn——sow 30 March – 27 August
Corn poppy——sow from 27 February
Cosmosfrom 17 Februaryfrom 3 Aprilfrom 24 April
Cucumber26 March – 2 September23 April – 30 September14 May – 30 September
Daikon——sow 27 February – 9 October
Delphiniumfrom 9 December—from 27 February
Dill——sow 27 February – 22 October
Edging lobeliafrom 2 January—from 27 March
Eggplant22 February – 26 June23 April – 25 August14 May – 25 August
Florence fennel20 January – 6 September6 March – 21 October27 March – 21 October
Foxglovefrom 21 November—from 27 February
Garden sorrel——sow 27 February – 10 October
Green Beans——sow 24 April – 4 September
Hollyhock——sow from 27 February
Hyssop——sow 27 February – 2 September
Kale——sow 27 February – 4 October
Kiwano27 February – 9 September31 March – 11 October21 April – 11 October
Kohlrabi——sow 27 February – 14 October
Leek28 November – 18 June6 February – 27 August27 February – 27 August
Lemon balm——sow 27 February – 6 October
Lettuce——sow 27 February – 19 October
Lisianthusfrom 11 Novemberfrom 6 Februaryfrom 27 February
Lovage——sow from 27 February
Luffa12 March – 4 July23 April – 15 August14 May – 15 August
Marigoldfrom 23 Januaryfrom 6 Marchfrom 27 March
Marjoram22 February – 21 September—14 May – 20 November
Melon26 March – 20 August23 April – 17 September14 May – 17 September
Microgreens——sow 24 April – 1 December
Moringa7 March – 26 September1 May – 20 November22 May – 20 November
Moss rosefrom 9 January—from 27 March
Mustard greens——sow 27 February – 31 October
Napa cabbage1 February – 1 October6 March – 3 November27 March – 3 November
Nasturtiumfrom 27 Januaryfrom 6 Marchfrom 27 March
Okra12 March – 14 September23 April – 26 October14 May – 26 October
Oregano8 December – 11 September6 February – 10 November27 February – 10 November
Pansyfrom 12 Decemberfrom 6 Februaryfrom 27 February
Parsley——sow 27 February – 30 September
Parsnip——sow 27 February – 19 August
Peanut17 March – 10 August23 April – 16 September14 May – 16 September
Peas——sow 27 February – 2 October
Petuniafrom 19 Februaryfrom 23 Aprilfrom 14 May
Physalis14 February – 7 August31 March – 21 September21 April – 21 September
Pumpkin12 March – 9 July23 April – 20 August14 May – 20 August
Purple coneflowerfrom 6 December—from 27 February
Radish——sow 27 February – 15 November
Sage19 December – 7 September6 February – 26 October27 February – 26 October
Scarlet sagefrom 7 February—from 21 April
Snapdragonfrom 3 Decemberfrom 6 Februaryfrom 27 February
Soybean——sow 14 May – 26 September
Spinach——sow 27 February – 21 October
Stevia10 February – 29 July31 March – 16 September21 April – 16 September
Stock——sow from 27 February
Sunflower——sow from 24 April
Sweet alyssum——sow from 27 February
Sweet Corn18 February – 21 September12 March – 13 October2 April – 13 October
Sweet peafrom 26 Decemberfrom 6 Februaryfrom 27 February
Sweet William——sow from 27 February
Swiss Chard——sow 27 February – 16 October
Thyme——sow 27 February – 27 August
Tomato7 February – 4 July31 March – 25 August21 April – 25 August
Turnip——sow 27 February – 18 October
Watercress——sow 27 February – 29 October
Watermelon26 March – 8 August23 April – 5 September14 May – 5 September
Zinniafrom 27 Marchfrom 1 Mayfrom 22 May
Zucchini2 April – 7 September23 April – 28 September14 May – 28 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 Okayama

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 5 days before the last spring frost and 15 °C 32 days after it.

SoilDateAgainst the last spring frost
5 °Calready in the first week of January—
10 °C15 March5 days earlier
15 °C21 April32 days later
18 °C14 May55 days later

Frost dates near Okayama

Of the nearest cities on our list, the last spring frost ends earliest in Kitakyushu (17 February) and latest in Hiroshima (9 April).

CityDistanceLast spring frostFirst autumn frost
Hiroshima138 km9 April25 November
Osaka145 km14 March17 December
Kyoto174 km22 March7 December
Nagoya278 km22 March10 December
Kitakyushu292 km17 February—

Seeds, seedlings and markets in Okayama

Within 15 km of Okayama OpenStreetMap lists 8 garden centres, 5 farm-supply shops, 3 markets and 19 farm shops (collected 28 October 2026). The nearest garden centre to the city centre is 瀬戸内庭園資材, 12 km away.

Places: © OpenStreetMap contributors, ODbL.

What to grow at home in winter in Okayama

Frosts in Okayama usually come from about 15 December to about 20 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 Okayama by month

Average weather in Okayama over 2016–2025: the warmest month is August. Months that average 20 °C or more by day: May–October (22.4–32.4 °C). Months that average 30 °C or more by day: July (30.5 °C) and August (32.4 °C). No month averages below 0 °C at night; the coldest nights, in January, average 0.3 °C. About 1448 mm of rain falls in a year, on 118 days; July is the wettest month (230 mm) and January the driest (37 mm).

MonthDay, °CNight, °CRain, mmRainy days
January8.90.3374
February9.70.6487
March14.34.39610
April19.1913510
May23.413.613310
June26.718.320814
July30.523.123015
August32.424.216213
September28.320.819314
October22.414.211510
November16.77.7546
December10.82.3375

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 15 November
Crocus15 November – end of December
Daffodil15 November – end of December
Garlic15 November – end of December
Grape hyacinthby 15 November
Helleboreby 15 November
Hyacinth15 November – end of December
Lilyby 15 November
Ornamental onionby 15 November
Peonyby 15 November
Saffronby 15 November
Snowdropby 15 November
Tulip15 November – end of December
Wild garlicby 15 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).