When to plant cucumbers in Kumamoto: 2 May – 18 September

In Kumamoto, cucumber: sow for seedlings from 14 March to 21 August; plant into a greenhouse from 11 April to 18 September; plant out into open ground from 2 May to 18 September.

Cucumber in Kumamoto: soil, season and weather

In Kumamoto the soil, not frost, sets the date: the last frost is over around 18 March, but the top 7 cm of soil reaches 18 °C — the minimum on the cucumber card — only around 2 May, 45 days later.

Last spring frost	18 March
Top 7 cm of soil at 18 °C	2 May, 45 days after the last frost
Into an unheated greenhouse	11 April – 18 September; April outside: 10.4 °C at night, 20.6 °C by day; card 18–25 °C
First autumn frost	3 December, 215 days after the start
Days in the bed to the first harvest (card)	34
First harvest, if planted in this window	5 June – 22 October
Days left for picking	181
Daylight	12:37 on 4 April, 13:30 on 2 May
Watering outdoors when fruiting (card)	every 2 days; the driest month, December, has 9 rainy days

The same dates in Kumamoto hold for Bell Pepper, Eggplant, Zucchini, Pumpkin and Watermelon.

Cucumber in Kumamoto: care after planting

Planted on 2 May: in the first weeks water every 4 days.

Feeding, by the card’s schedule from that day:

9 May — feed: nitrogen

Pests and diseases of cucumber to watch for:

Dates count from the first planting day of the window above; a later planting moves them by as many days.

Weather in Kumamoto during the cucumber season

No month of the season averages above the cucumber card's 18–35 °C by day; the warmest, August, averages 32.3 °C. Months that stay below 18 °C even by day on average: December (12.4 °C). Nights average below 18 °C in May and October–December (2.9–14.8 °C).

Month	Day, °C	Night, °C	Rain, mm	Rainy days	Daylight on the 15th
May	24.3	14.6	255	14	13:50
June	27.2	19.3	442	18	14:18
July	30.8	23.4	381	19	14:07
August	32.3	23.8	258	17	13:23
September	29.4	21.1	205	17	12:24
October	24.4	14.8	112	11	11:24
November	18.5	8.3	89	9	10:29
December	12.4	2.9	70	9	10:00

ERA5 2016–2025, Open-Meteo

Cucumber in nearby cities

All the nearest cities on our list plant cucumber later than Kumamoto; the closest date is in Fukuoka, 3 days later.

City	Distance	Date	Difference
Fukuoka	92 km	5 May – 6 October	3 days later
Kitakyushu	121 km	from 15 May	13 days later
Kagoshima	134 km	6 May – 11 October	4 days later
Hiroshima	239 km	26 May – 10 September	24 days later
Busan	305 km	15 May – 7 September	13 days later
Ulsan	331 km	18 May – 1 September	16 days later

Where to buy cucumber plants and seeds near Kumamoto

Buy plants ready to set out from 2 May to 18 September (from 11 April to 18 September for an unheated greenhouse); seed for raising your own is sown from 14 March to 21 August. Within 15 km of Kumamoto OpenStreetMap lists 3 garden centres, 5 markets and 2 farm shops (collected 28 October 2026).

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.

Questions