When to plant watermelons in Hasselt: 30 May – 9 August

In Hasselt, watermelon: sow for seedlings from 11 April to 12 July; plant into a greenhouse from 9 May to 9 August; plant out into open ground from 30 May to 9 August.

Watermelon in Hasselt: soil, season and weather

In Hasselt the soil, not frost, sets the date: the last frost is over around 19 April, but the top 7 cm of soil reaches 18 °C — the minimum on the watermelon card — only around 30 May, 41 days later.

Last spring frost	19 April
Top 7 cm of soil at 18 °C	30 May, 41 days after the last frost
Into an unheated greenhouse	9 May – 9 August; May outside: 8.8 °C at night, 19.2 °C by day; card 18–35 °C
First autumn frost	18 November, 172 days after the start
Days in the bed to the first harvest (card)	59
First harvest, if planted in this window	28 July – 7 October
Days left for picking	113
Daylight	14:49 on 2 May, 16:08 on 30 May
Watering outdoors when fruiting (card)	every 5 days; the driest month, September, has 11 rainy days

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

Watermelon in Hasselt: care after planting

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

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

30 May — 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 Hasselt during the watermelon season

No month of the season averages above the watermelon card's 18–35 °C by day; the warmest, August, averages 23.9 °C. Months that stay below 18 °C even by day on average: October (15.8 °C) and November (10.1 °C). Nights average below 18 °C in every month of the season, from 4.4 °C to 14.3 °C.

Month	Day, °C	Night, °C	Rain, mm	Rainy days	Daylight on the 15th
May	19.2	8.8	68	11	15:31
June	23	13.2	79	13	16:30
July	23.8	14	77	12	16:06
August	23.9	14.3	70	12	14:36
September	20.6	11.5	65	11	12:42
October	15.8	9.1	78	14	10:47
November	10.1	4.4	74	14	8:58

ERA5 2016–2025, Open-Meteo

Watermelon in nearby cities

All the nearest cities on our list plant watermelon later than Hasselt; the closest date is in Leuven, 1 day later.

City	Distance	Date	Difference
Liège	37 km	4 June – 10 August	5 days later
Leuven	45 km	31 May – 13 August	1 day later
Namur	61 km	11 June – 6 August	12 days later
Brussels	70 km	8 June – 13 August	9 days later
Antwerp	73 km	31 May – 13 August	1 day later
Charleroi	86 km	10 June – 6 August	11 days later

Where to buy watermelon plants and seeds near Hasselt

Buy plants ready to set out from 30 May to 9 August (from 9 May to 9 August for an unheated greenhouse); seed for raising your own is sown from 11 April to 12 July. Within 15 km of Hasselt OpenStreetMap lists 21 garden centres, 1 farm-supply shop, 1 plant nursery, 2 markets and 14 farm shops (collected 27 October 2026).

Marktplein — market
12 km
CSA De Kriekelaer — farm shop
4 km
Jappelhof — farm shop
5 km
Het Aardbeienkraampje — farm shop
10 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