When to plant cucumbers in Seoul: 15 May – 22 August

In Seoul, cucumber: sow for seedlings from 27 March to 25 July; plant into a greenhouse from 24 April to 22 August; plant out into open ground from 15 May to 22 August.

Cucumber in Seoul: soil, season and weather

In Seoul the soil, not frost, sets the date: the last frost is over around 29 March, but the top 7 cm of soil reaches 18 °C — the minimum on the cucumber card — only around 15 May, 47 days later.

Last spring frost	29 March
Top 7 cm of soil at 18 °C	15 May, 47 days after the last frost
Into an unheated greenhouse	24 April – 22 August; April outside: 6.7 °C at night, 17.8 °C by day; card 18–25 °C
First autumn frost	6 November, 175 days after the start
Days in the bed to the first harvest (card)	34
First harvest, if planted in this window	18 June – 25 September
Days left for picking	141
Daylight	13:13 on 17 April, 14:11 on 15 May
Watering outdoors when fruiting (card)	every 2 days; the driest month, November, has 6 rainy days

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

Cucumber in Seoul: care after planting

Planted on 15 May: in the first weeks water every 4 days.

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

22 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 Seoul during the cucumber season

No month of the season averages above the cucumber card's 18–35 °C by day; the warmest, August, averages 29.5 °C. Months that stay below 18 °C even by day on average: November (11.1 °C). Nights average below 18 °C in May, June and September–November (1.6–17.7 °C).

Month	Day, °C	Night, °C	Rain, mm	Rainy days	Daylight on the 15th
May	22.7	12.1	107	9	14:11
June	27.1	17.7	126	10	14:45
July	29.3	22.4	310	17	14:31
August	29.5	22.5	276	16	13:38
September	25.3	17.4	148	10	12:28
October	18.5	9.5	78	7	11:16
November	11.1	1.6	52	6	10:10

ERA5 2016–2025, Open-Meteo

Cucumber in nearby cities

All the nearest cities on our list plant cucumber later than Seoul; the closest date is in Daegu, 1 day later.

City	Distance	Date	Difference
Chuncheon	74 km	24 May – 16 August	9 days later
Daejeon	139 km	17 May – 28 August	2 days later
Gangneung	169 km	17 May – 6 September	2 days later
Jeonju	194 km	19 May – 2 September	4 days later
Daegu	236 km	16 May – 6 September	1 day later
Gwangju	266 km	17 May – 8 September	2 days later

Where to buy cucumber plants and seeds near Seoul

Buy plants ready to set out from 15 May to 22 August (from 24 April to 22 August for an unheated greenhouse); seed for raising your own is sown from 27 March to 25 July. Within 15 km of Seoul OpenStreetMap lists 1 garden centre, 2 plant nurseries and 85 markets (collected 28 October 2026).

Inheon Marketplace — market
인헌6길 16 농, 서울특별시 · 10 km
Local street market — market
동일로143길, 서울특별시 · 9 km
경창시장 — market
중앙로53길, 서울특별시 · 14 km
곤충식물원 — plant nursery
5 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