Gardening in Japan: climate, frost dates and crops by region

Climate zones of Japan

By the days between the last spring frost and the first autumn frost.

How the regions of Japan differ

Splitting the cities in two — north (Sapporo, Sendai, Niigata and 4 more) and south (Okayama, Hiroshima, Kitakyushu and 4 more): the last spring frost comes about 15 days later in the north.

The gap between the warmest month’s days and the coldest month’s nights is widest in Sapporo (34.2 °C) and smallest in Naha (15 °C): the smaller it is, the milder both winter and summer. Kagoshima is the wettest of these cities with 2,616 mm a year, Sapporo the driest with 1,410 mm. The hottest summer days are in Osaka (32.5 °C on average in the warmest month), the coolest in Sapporo (22.3 °C). In 6 of the 15 cities at least one month averages below 0 °C at night; the longest such winter is in Sapporo (November–April).

Which crops suit which part of Japan

Season long enough: the days from planting to the first autumn frost cover the days to the first harvest on the plant card. 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.

Cities without a spring frost: months that suit each crop

Months whose average day is not above the highest temperature on the plant card and whose average night is not below its lowest.

Cities of Japan: weather in numbers

ERA5 2016–2025 via Open-Meteo, 25 km grid cell of each city; dates by the Greenly calendar and the plant cards.

More about Japan

• Japan: frost dates by city
• Where to buy seeds and plants
• When to plant tomatoes in Japan
• When to plant cucumbers in Japan
• When to plant peas in Japan
• When to plant garlic in Japan
• Gardening by country