When to plant cucumbers in Derry: 13 July – 6 September

In Derry, cucumber: sow for seedlings from 25 May to 9 August; plant into a greenhouse from 22 June to 6 September; plant out into open ground from 13 July to 6 September. For plants and seeds, the places nearby include Culmore Farm Shop (farm shop, 7 km); addresses and opening hours are below.

Cucumber in Derry: soil, season and weather

In Derry the soil, not frost, sets the date: the last frost is over around 23 March, but the top 7 cm of soil reaches 18 °C — the minimum on the cucumber card — only around 13 July, 112 days later.

Last spring frost	23 March
Top 7 cm of soil at 18 °C	13 July, 112 days after the last frost
Into an unheated greenhouse	22 June – 6 September; June outside: 10.4 °C at night, 16.8 °C by day; card 18–25 °C
First autumn frost	21 November, 131 days after the start
Days in the bed to the first harvest (card)	34
First harvest, if planted in this window	16 August – 10 October
Days left for picking	97
Daylight	17:20 on 15 June, 16:56 on 13 July
Watering outdoors when fruiting (card)	every 2 days; the driest month, November, has 17 rainy days

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

Cucumber in Derry: care after planting

Planted on 13 July: in the first weeks water every 4 days.

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

20 July — 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 Derry during the cucumber season

No month of the season averages above the cucumber card's 18–35 °C by day; the warmest, July, averages 17.7 °C. Months that stay below 18 °C even by day on average: July–November (9.7–17.7 °C). Nights average below 18 °C in every month of the season, from 5.4 °C to 11.9 °C.

Month	Day, °C	Night, °C	Rain, mm	Rainy days	Daylight on the 15th
July	17.7	11.7	104	19	16:51
August	17.7	11.9	113	20	15:02
September	15.9	10.3	101	18	12:48
October	12.9	8.4	106	17	10:35
November	9.7	5.4	90	17	8:26

ERA5 2016–2025, Open-Meteo

Cucumber in nearby cities

Around Derry, Sligo is 13 days earlier and Dundalk 4 days later.

City	Distance	Date	Difference
Letterkenny	26 km	7 July – 13 September	6 days earlier
Belfast	100 km	7 July – 4 September	6 days earlier
Sligo	110 km	30 June – 6 September	13 days earlier
Dundalk	126 km	17 July – 5 September	4 days later
Athlone	180 km	13 July – 11 September	same day
Dublin	196 km	16 July – 9 September	3 days later

Where to buy cucumber plants and seeds near Derry

Buy plants ready to set out from 13 July to 6 September (from 22 June to 6 September for an unheated greenhouse); seed for raising your own is sown from 25 May to 9 August. Within 15 km of Derry OpenStreetMap lists 1 garden centre and 1 farm shop (collected 28 October 2026).

Culmore Farm Shop — farm shop
Culmore Road, Culmore · 7 km
Altnagelvin Garden Centre — garden centre
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