When to plant watermelons in Dundalk: 17 July – 11 August

In Dundalk, watermelon: sow for seedlings from 29 May to 14 July; plant into a greenhouse from 26 June to 11 August; plant out into open ground from 17 July to 11 August. For plants and seeds, the places nearby include Hardys (farm supply, 2 km); addresses and opening hours are below.

Watermelon in Dundalk: soil, season and weather

In Dundalk the soil, not frost, sets the date: the last frost is over around 20 March, but the top 7 cm of soil reaches 18 °C — the minimum on the watermelon card — only around 17 July, 119 days later.

Last spring frost	20 March
Top 7 cm of soil at 18 °C	17 July, 119 days after the last frost
Into an unheated greenhouse	26 June – 11 August; June outside: 10.6 °C at night, 17.6 °C by day; card 18–35 °C
First autumn frost	20 November, 126 days after the start
Days in the bed to the first harvest (card)	59
First harvest, if planted in this window	14 September – 9 October
Days left for picking	67
Daylight	17:09 on 19 June, 16:34 on 17 July
Watering outdoors when fruiting (card)	every 5 days; the driest month, July, has 15 rainy days

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

Watermelon in Dundalk: care after planting

Planted on 17 July: in the first weeks water every 5 days.

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

17 July — 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 Dundalk during the watermelon season

No month of the season averages above the watermelon card's 18–35 °C by day; the warmest, July, averages 19 °C. Months that stay below 18 °C even by day on average: September (16.5 °C), October (13.5 °C) and November (10 °C). Nights average below 18 °C in every month of the season, from 5 °C to 12.1 °C.

Month	Day, °C	Night, °C	Rain, mm	Rainy days	Daylight on the 15th
July	19	12.1	88	15	16:39
August	18.7	12	98	15	14:55
September	16.5	10.1	103	15	12:46
October	13.5	8.2	98	15	10:38
November	10	5	91	14	8:35

ERA5 2016–2025, Open-Meteo

Watermelon in nearby cities

All the nearest cities on our list plant watermelon earlier than Dundalk; the closest date is in Dublin, 1 day earlier.

City	Distance	Date	Difference
Dublin	73 km	16 July – 15 August	1 day earlier
Belfast	73 km	7 July – 10 August	10 days earlier
Athlone	120 km	13 July – 17 August	4 days earlier
Derry	126 km	13 July – 12 August	4 days earlier
Letterkenny	137 km	7 July – 19 August	10 days earlier
Sligo	138 km	30 June – 12 August	17 days earlier

Where to buy watermelon plants and seeds near Dundalk

Buy plants ready to set out from 17 July to 11 August (from 26 June to 11 August for an unheated greenhouse); seed for raising your own is sown from 29 May to 14 July. Within 15 km of Dundalk OpenStreetMap lists 2 garden centres, 2 farm-supply shops and 2 farm shops (collected 28 October 2026).

Hardys — farm supply
Lisdoo, Newry Road, Dundalk · 2 km · joesphwallsonline.com
Dundalk Garden Centre — garden centre
2 km
Carrive Grove Garden Centre — garden centre
10 km
Corderry Fruit Farm — farm supply
9 km · corderry.ie

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