When to plant watermelons in Fukuoka: 5 May – 11 September

In Fukuoka, watermelon: sow for seedlings from 17 March to 14 August; plant into a greenhouse from 14 April to 11 September; plant out into open ground from 5 May to 11 September.

Watermelon in Fukuoka: soil, season and weather

In Fukuoka the soil, not frost, sets the date: the last frost is over around 25 February, but the top 7 cm of soil reaches 18 °C — the minimum on the watermelon card — only around 5 May, 69 days later.

Last spring frost	25 February
Top 7 cm of soil at 18 °C	5 May, 69 days after the last frost
Into an unheated greenhouse	14 April – 11 September; April outside: 10.7 °C at night, 19.7 °C by day; card 18–35 °C
First autumn frost	21 December, 230 days after the start
Days in the bed to the first harvest (card)	59
First harvest, if planted in this window	3 July – 9 November
Days left for picking	171
Daylight	12:44 on 7 April, 13:37 on 5 May
Watering outdoors when fruiting (card)	every 5 days; the driest month, December, has 8 rainy days

The same dates in Fukuoka hold for Cucumber, Bell Pepper, Eggplant, Zucchini and Pumpkin.

Watermelon in Fukuoka: care after planting

Planted on 5 May: in the first weeks water every 5 days.

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

5 May — feed: balanced (NPK)

Pests and diseases of watermelon 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 Fukuoka during the watermelon season

No month of the season averages above the watermelon 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: November (17.5 °C) and December (11.2 °C). Nights average below 18 °C in May and October–December (4.2–15.4 °C).

Month	Day, °C	Night, °C	Rain, mm	Rainy days	Daylight on the 15th
May	24	15.1	185	12	13:53
June	27.1	19.6	266	17	14:22
July	30.7	23.8	304	19	14:11
August	32.3	24.6	253	16	13:25
September	28.5	21.4	229	17	12:25
October	23	15.4	104	10	11:23
November	17.5	9.3	76	7	10:26
December	11.2	4.2	60	8	9:56

ERA5 2016–2025, Open-Meteo

Watermelon in nearby cities

Around Fukuoka, Kumamoto is 3 days earlier and Hiroshima 21 days later.

City	Distance	Date	Difference
Kitakyushu	55 km	from 15 May	10 days later
Kumamoto	92 km	2 May – 24 August	3 days earlier
Hiroshima	209 km	26 May – 16 August	21 days later
Busan	215 km	15 May – 13 August	10 days later
Kagoshima	222 km	6 May – 16 September	1 day later
Ulsan	239 km	18 May – 7 August	13 days later

Where to buy watermelon plants and seeds near Fukuoka

Buy plants ready to set out from 5 May to 11 September (from 14 April to 11 September for an unheated greenhouse); seed for raising your own is sown from 17 March to 14 August. Within 15 km of Fukuoka OpenStreetMap lists 10 garden centres, 1 plant nursery, 3 markets and 3 farm shops (collected 28 October 2026).

ふくおかフラワー — garden centre
7 km
HANA MASA — garden centre
5 km
ハーブショップ Grosso for kanatake — garden centre
11 km
初御代桜 — plant nursery
12 km

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