When to plant tomatoes in San Sebastián: 1 May – 13 August

In San Sebastián, tomato: sow for seedlings from 17 February to 22 June; plant into a greenhouse from 10 April to 13 August; plant out into open ground from 1 May to 13 August. For plants and seeds, the places nearby include Loraldi (garden centre, 6 km) and Totem mendi-tresnak (farm supply, 7 km); addresses and opening hours are below.

Tomato in San Sebastián: soil, season and weather

In San Sebastián the soil, not frost, sets the date: the last frost is over around 22 January, but the top 7 cm of soil reaches 15 °C — the minimum on the tomato card — only around 1 May, 99 days later.

Last spring frost	22 January
Top 7 cm of soil at 15 °C	1 May, 99 days after the last frost
Into an unheated greenhouse	10 April – 13 August; April outside: 8.3 °C at night, 15.9 °C by day; card 16–27 °C
First autumn frost	3 December, 216 days after the start
Days in the bed to the first harvest (card)	70
First harvest, if planted in this window	10 July – 22 October
Days left for picking	146
Daylight	11:37 on 10 March, 14:07 on 1 May
Watering outdoors when fruiting (card)	every 3 days; the driest month, July, has 13 rainy days

Tomato in San Sebastián: care after planting

Planted on 1 May: in the first weeks water every 4 days.

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

1 May — feed: balanced (NPK)
29 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 San Sebastián during the tomato season

No month of the season averages above the tomato card's 16–27 °C by day; the warmest, August, averages 23.6 °C. Months that stay below 16 °C even by day on average: November (14.7 °C) and December (12.8 °C). Nights average below 16 °C in May, June and September–December (6.9–14.3 °C).

Month	Day, °C	Night, °C	Rain, mm	Rainy days	Daylight on the 15th
May	18.2	10.7	127	17	14:40
June	21.3	14.2	109	14	15:23
July	22.7	16	73	13	15:06
August	23.6	16.3	99	12	14:00
September	22.1	14.3	127	13	12:33
October	19.7	12.4	139	13	11:05
November	14.7	8.6	230	18	9:44
December	12.8	6.9	189	15	9:00

ERA5 2016–2025, Open-Meteo

Tomato in nearby cities

Around San Sebastián, Bayonne is 12 days earlier and Pamplona 13 days later.

City	Distance	Date	Difference
Bayonne	45 km	19 April – 27 August	12 days earlier
Pamplona	63 km	14 May – 10 August	13 days later
Vitoria-Gasteiz	77 km	13 May – 4 August	12 days later
Bilbao	77 km	12 May – 5 September	11 days later
Logroño	102 km	6 May – 14 August	5 days later
Pau	131 km	4 May – 14 August	3 days later

Where to buy tomato plants and seeds near San Sebastián

Buy plants ready to set out from 1 May to 13 August (from 10 April to 13 August for an unheated greenhouse); seed for raising your own is sown from 17 February to 22 June. Within 15 km of San Sebastián OpenStreetMap lists 4 garden centres, 3 farm-supply shops, 6 markets and 4 farm shops (collected 27 October 2026).

Endanea Garden Center — garden centre
Jaitzubia auzoa 40, 20280 Hondarribia · 13 km · endanea.com
Loraldi — garden centre
Iparralde bidea, 20115 Astigarraga · 6 km · loraldi.com
Alkartasuna Baserritarren Kooperatiba — farm supply
Atallu kalea 26 · Mon–Fri 09:00–13:00, 16:00–19:30; Sat 09:00–13:00 · 8 km · alkartasuna.eus
Totem mendi-tresnak — farm supply
Zikuñaga bailara 17, 20120 Hernani · 7 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.

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