When to plant cucumbers in Swansea: 21 June – 16 September

In Swansea, cucumber: sow for seedlings from 3 May to 19 August; plant into a greenhouse from 31 May to 16 September; plant out into open ground from 21 June to 16 September.

Cucumber in Swansea: soil, season and weather

In Swansea the soil, not frost, sets the date: the last frost is over around 28 February, but the top 7 cm of soil reaches 18 °C — the minimum on the cucumber card — only around 21 June, 113 days later.

Last spring frost	28 February
Top 7 cm of soil at 18 °C	21 June, 113 days after the last frost
Into an unheated greenhouse	31 May – 16 September; May outside: 9.4 °C at night, 16 °C by day; card 18–25 °C
First autumn frost	1 December, 163 days after the start
Days in the bed to the first harvest (card)	34
First harvest, if planted in this window	25 July – 20 October
Days left for picking	129
Daylight	16:01 on 24 May, 16:40 on 21 June
Watering outdoors when fruiting (card)	every 2 days; the driest month, June, has 16 rainy days

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

Cucumber in Swansea: care after planting

Planted on 21 June: in the first weeks water every 4 days.

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

28 June — 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 Swansea during the cucumber season

No month of the season averages above the cucumber card's 18–35 °C by day; the warmest, July, averages 19.7 °C. Months that stay below 18 °C even by day on average: September–December (9.4–17.8 °C). Nights average below 18 °C in every month of the season, from 5.6 °C to 14.1 °C.

Month	Day, °C	Night, °C	Rain, mm	Rainy days	Daylight on the 15th
June	18.3	12.4	101	16	16:38
July	19.7	13.9	117	16	16:13
August	19.4	14.1	139	18	14:40
September	17.8	12.5	168	16	12:43
October	14.7	10.2	187	18	10:45
November	11.2	6.8	175	18	8:53
December	9.4	5.6	203	19	7:51

ERA5 2016–2025, Open-Meteo

Cucumber in nearby cities

Around Swansea, Bristol is 2 days earlier and Plymouth 26 days later.

City	Distance	Date	Difference
Cardiff	55 km	24 June – 7 September	3 days later
Bristol	95 km	19 June – 7 September	2 days earlier
Exeter	104 km	23 June – 12 September	2 days later
Worcester	134 km	19 June – 7 September	2 days earlier
Plymouth	140 km	17 July – 16 September	26 days later
Birmingham	170 km	20 June – 4 September	1 day earlier

Where to buy cucumber plants and seeds near Swansea

Buy plants ready to set out from 21 June to 16 September (from 31 May to 16 September for an unheated greenhouse); seed for raising your own is sown from 3 May to 19 August. Within 15 km of Swansea OpenStreetMap lists 1 garden centre, 2 markets and 1 farm shop (collected 20 October 2026).

Pontarddulais Garden Centre — garden centre
11 km
Swansea Market — market
0 km
Neath Indoor Market — market
10 km
Murton Farm Shop — farm shop
8 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