When to plant watermelons in Sligo: 30 June – 12 August

In Sligo, watermelon: sow for seedlings from 12 May to 15 July; plant into a greenhouse from 9 June to 12 August; plant out into open ground from 30 June to 12 August. For plants and seeds, the places nearby include Horkans (garden centre, 1 km) and Homeland Plus (farm shop, 2 km); addresses and opening hours are below.

Watermelon in Sligo: soil, season and weather

In Sligo the soil, not frost, sets the date: the last frost is over around 8 April, but the top 7 cm of soil reaches 18 °C — the minimum on the watermelon card — only around 30 June, 83 days later.

Last spring frost	8 April
Top 7 cm of soil at 18 °C	30 June, 83 days after the last frost
Into an unheated greenhouse	9 June – 12 August; June outside: 10.2 °C at night, 17 °C by day; card 18–35 °C
First autumn frost	21 November, 144 days after the start
Days in the bed to the first harvest (card)	59
First harvest, if planted in this window	28 August – 10 October
Days left for picking	85
Daylight	16:51 on 2 June, 17:08 on 30 June
Watering outdoors when fruiting (card)	every 5 days; the driest month, November, has 19 rainy days

The same dates in Sligo hold for Cucumber, Bell Pepper, Eggplant, Zucchini and Pumpkin.

Watermelon in Sligo: care after planting

Planted on 30 June: in the first weeks water every 5 days.

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

30 June — feed: balanced (NPK)

Pests and diseases of watermelon 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 Sligo during the watermelon season

No month of the season averages above the watermelon card's 18–35 °C by day; the warmest, August, averages 17.9 °C. Months that stay below 18 °C even by day on average: June–November (9.6–17.9 °C). Nights average below 18 °C in every month of the season, from 5 °C to 11.6 °C.

Month	Day, °C	Night, °C	Rain, mm	Rainy days	Daylight on the 15th
June	17	10.2	125	20	17:10
July	17.7	11.6	128	21	16:42
August	17.9	11.6	157	22	14:57
September	15.9	9.9	123	19	12:47
October	12.9	8	138	19	10:37
November	9.6	5	115	19	8:33

ERA5 2016–2025, Open-Meteo

Watermelon in nearby cities

All the nearest cities on our list plant watermelon later than Sligo; the closest date is in Letterkenny, 7 days later.

City	Distance	Date	Difference
Letterkenny	91 km	7 July – 19 August	7 days later
Athlone	101 km	13 July – 17 August	13 days later
Derry	110 km	13 July – 12 August	13 days later
Galway	118 km	13 July – 19 August	13 days later
Dundalk	138 km	17 July – 11 August	17 days later
Belfast	168 km	7 July – 10 August	7 days later

Where to buy watermelon plants and seeds near Sligo

Buy plants ready to set out from 30 June to 12 August (from 9 June to 12 August for an unheated greenhouse); seed for raising your own is sown from 12 May to 15 July. Within 15 km of Sligo OpenStreetMap lists 2 garden centres and 1 farm shop (collected 20 October 2026).

Horkans — garden centre
Mon–Sun 10:00–18:00 · 1 km
Homebase — garden centre
Carraroe Retail Park, Sligo · 2 km
Homeland Plus — farm shop
Deep Water Quay, F91 HR53 Sligo · 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.

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