When to plant cucumbers in Daejeon: 17 May – 28 August

In Daejeon, cucumber: sow for seedlings from 29 March to 31 July; plant into a greenhouse from 26 April to 28 August; plant out into open ground from 17 May to 28 August.

Cucumber in Daejeon: soil, season and weather

In Daejeon the soil, not frost, sets the date: the last frost is over around 1 April, but the top 7 cm of soil reaches 18 °C — the minimum on the cucumber card — only around 17 May, 46 days later.

Last spring frost	1 April
Top 7 cm of soil at 18 °C	17 May, 46 days after the last frost
Into an unheated greenhouse	26 April – 28 August; April outside: 6.8 °C at night, 18.5 °C by day; card 18–25 °C
First autumn frost	12 November, 179 days after the start
Days in the bed to the first harvest (card)	34
First harvest, if planted in this window	20 June – 1 October
Days left for picking	145
Daylight	13:15 on 19 April, 14:08 on 17 May
Watering outdoors when fruiting (card)	every 2 days; the driest month, November, has 5 rainy days

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

Cucumber in Daejeon: care after planting

Planted on 17 May: in the first weeks water every 4 days.

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

24 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 Daejeon during the cucumber season

No month of the season averages above the cucumber card's 18–35 °C by day; the warmest, August, averages 30 °C. Months that stay below 18 °C even by day on average: November (12.1 °C). Nights average below 18 °C in May, June and September–November (2.4–17.2 °C).

Month	Day, °C	Night, °C	Rain, mm	Rainy days	Daylight on the 15th
May	23.2	11.8	89	9	14:05
June	27.4	17.1	145	11	14:37
July	29.2	21.6	265	17	14:25
August	30	22	219	18	13:34
September	25.2	17.2	168	11	12:27
October	18.7	9.8	78	8	11:18
November	12.1	2.4	45	5	10:15

ERA5 2016–2025, Open-Meteo

Cucumber in nearby cities

Around Daejeon, Seoul is 2 days earlier and Chuncheon 7 days later.

City	Distance	Date	Difference
Jeonju	63 km	19 May – 2 September	2 days later
Daegu	121 km	16 May – 6 September	1 day earlier
Seoul	139 km	15 May – 22 August	2 days earlier
Gwangju	140 km	17 May – 8 September	same day
Chuncheon	172 km	24 May – 16 August	7 days later
Ulsan	195 km	18 May – 1 September	1 day later

Where to buy cucumber plants and seeds near Daejeon

Buy plants ready to set out from 17 May to 28 August (from 26 April to 28 August for an unheated greenhouse); seed for raising your own is sown from 29 March to 31 July. Within 15 km of Daejeon OpenStreetMap lists 24 markets and 1 farm shop (collected 28 October 2026).

건해산물경매장 — market
2 km
수산1경매장 — market
2 km
양파경매동 — market
2 km
채소경매동 — market
2 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