When to plant tomatoes in Gangneung: 28 April – 1 August

In Gangneung, tomato: sow for seedlings from 14 February to 10 June; plant into a greenhouse from 7 April to 1 August; plant out into open ground from 28 April to 1 August.

Tomato in Gangneung: soil, season and weather

In Gangneung the soil, not frost, sets the date: the last frost is over around 19 March, but the top 7 cm of soil reaches 15 °C — the minimum on the tomato card — only around 28 April, 40 days later.

Last spring frost	19 March
Top 7 cm of soil at 15 °C	28 April, 40 days after the last frost
Into an unheated greenhouse	7 April – 1 August; April outside: 8.2 °C at night, 16.9 °C by day; card 16–27 °C
First autumn frost	21 November, 207 days after the start
Days in the bed to the first harvest (card)	70
First harvest, if planted in this window	7 July – 10 October
Days left for picking	137
Daylight	11:35 on 7 March, 13:38 on 28 April
Watering outdoors when fruiting (card)	every 3 days; the driest month, November, has 6 rainy days

Tomato in Gangneung: care after planting

Planted on 28 April: in the first weeks water every 4 days.

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

28 April — feed: balanced (NPK)
26 May — feed: nitrogen

Pests and diseases of tomato 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 Gangneung during the tomato season

Days average above the tomato card's 16–27 °C in July (27.9 °C) and August (28.4 °C). Months that stay below 16 °C even by day on average: November (13.1 °C). Nights average below 16 °C in April, May and October, November (5.1–13.3 °C).

Month	Day, °C	Night, °C	Rain, mm	Rainy days	Daylight on the 15th
April	16.9	8.2	67	8	13:09
May	21.6	13.3	75	9	14:11
June	25	18.1	100	10	14:46
July	27.9	22.4	229	15	14:32
August	28.4	22.8	307	17	13:39
September	23.9	18	226	15	12:28
October	18.4	11.6	172	12	11:16
November	13.1	5.1	48	6	10:10

ERA5 2016–2025, Open-Meteo

Tomato in nearby cities

Around Gangneung, Daegu is 6 days earlier and Chuncheon 15 days later.

City	Distance	Date	Difference
Chuncheon	103 km	13 May – 11 July	15 days later
Seoul	169 km	24 April – 17 July	4 days earlier
Daejeon	205 km	24 April – 23 July	4 days earlier
Daegu	211 km	22 April – 1 August	6 days earlier
Ulsan	248 km	22 April – 27 July	6 days earlier
Jeonju	265 km	25 April – 28 July	3 days earlier

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.

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