When to plant watermelons in Dortmund: 5 June – 7 August

In Dortmund, watermelon: sow for seedlings from 17 April to 10 July; plant into a greenhouse from 15 May to 7 August; plant out into open ground from 5 June to 7 August.

Watermelon in Dortmund: soil, season and weather

In Dortmund the soil, not frost, sets the date: the last frost is over around 17 April, but the top 7 cm of soil reaches 18 °C — the minimum on the watermelon card — only around 5 June, 49 days later.

Last spring frost	17 April
Top 7 cm of soil at 18 °C	5 June, 49 days after the last frost
Into an unheated greenhouse	15 May – 7 August; May outside: 8.7 °C at night, 18.6 °C by day; card 18–35 °C
First autumn frost	16 November, 164 days after the start
Days in the bed to the first harvest (card)	59
First harvest, if planted in this window	3 August – 5 October
Days left for picking	105
Daylight	15:13 on 8 May, 16:25 on 5 June
Watering outdoors when fruiting (card)	every 5 days; the driest month, November, has 14 rainy days

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

Watermelon in Dortmund: care after planting

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

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

5 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 Dortmund during the watermelon season

No month of the season averages above the watermelon card's 18–35 °C by day; the warmest, August, averages 23.8 °C. Months that stay below 18 °C even by day on average: October (15.3 °C) and November (9.6 °C). Nights average below 18 °C in every month of the season, from 4.2 °C to 14.6 °C.

Month	Day, °C	Night, °C	Rain, mm	Rainy days	Daylight on the 15th
June	22.9	13.3	78	12	16:36
July	23.4	14.2	78	14	16:12
August	23.8	14.6	72	13	14:40
September	20.2	11.6	72	12	12:43
October	15.3	9	77	15	10:45
November	9.6	4.2	71	14	8:54

ERA5 2016–2025, Open-Meteo

Watermelon in nearby cities

All the nearest cities on our list plant watermelon earlier than Dortmund; the closest date is in Bochum, 2 days earlier.

City	Distance	Date	Difference
Bochum	18 km	3 June – 11 August	2 days earlier
Essen	32 km	3 June – 12 August	2 days earlier
Duisburg	50 km	3 June – 13 August	2 days earlier
Münster	51 km	1 June – 12 August	4 days earlier
Düsseldorf	57 km	3 June – 12 August	2 days earlier
Cologne	73 km	3 June – 11 August	2 days earlier

Where to buy watermelon plants and seeds near Dortmund

Buy plants ready to set out from 5 June to 7 August (from 15 May to 7 August for an unheated greenhouse); seed for raising your own is sown from 17 April to 10 July. Within 15 km of Dortmund OpenStreetMap lists 24 garden centres, 2 farm-supply shops, 3 plant nurseries, 21 markets and 35 farm shops (collected 28 October 2026).

Marktplatz Werne — market
Wed, Sat 08:00–13:00 · 12 km
Castroper Altstadtmarkt — market
Tue 08:00–13:00; Thu 08:00–13:00; Sat 08:00–13:00 · 12 km
Stern — market
Thu 08:00–13:00 · 12 km
Ickerner Marktplatz — market
Tue 08:00–13:00; Fri 08:00–13:00 · 13 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