When to plant watermelons in Mannheim: 1 June – 11 August

In Mannheim, watermelon: sow for seedlings from 13 April to 14 July; plant into a greenhouse from 11 May to 11 August; plant out into open ground from 1 June to 11 August.

Watermelon in Mannheim: soil, season and weather

In Mannheim the soil, not frost, sets the date: the last frost is over around 14 April, but the top 7 cm of soil reaches 18 °C — the minimum on the watermelon card — only around 1 June, 48 days later.

Last spring frost	14 April
Top 7 cm of soil at 18 °C	1 June, 48 days after the last frost
Into an unheated greenhouse	11 May – 11 August; May outside: 9.7 °C at night, 19.9 °C by day; card 18–35 °C
First autumn frost	20 November, 172 days after the start
Days in the bed to the first harvest (card)	59
First harvest, if planted in this window	30 July – 9 October
Days left for picking	113
Daylight	14:47 on 4 May, 15:59 on 1 June
Watering outdoors when fruiting (card)	every 5 days; the driest month, August, has 11 rainy days

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

Watermelon in Mannheim: care after planting

Planted on 1 June: in the first weeks water every 5 days.

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

1 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 Mannheim during the watermelon season

No month of the season averages above the watermelon card's 18–35 °C by day; the warmest, July, averages 26.2 °C. Months that stay below 18 °C even by day on average: October (16.1 °C) and November (9.3 °C). Nights average below 18 °C in every month of the season, from 3.6 °C to 16 °C.

Month	Day, °C	Night, °C	Rain, mm	Rainy days	Daylight on the 15th
June	25.3	14.7	69	11	16:15
July	26.2	15.8	67	10	15:53
August	26.2	16	63	11	14:28
September	21.8	12.2	69	10	12:40
October	16.1	8.4	84	13	10:51
November	9.3	3.6	73	14	9:08

ERA5 2016–2025, Open-Meteo

Watermelon in nearby cities

Around Mannheim, Karlsruhe is 2 days earlier and Stuttgart 4 days later.

City	Distance	Date	Difference
Karlsruhe	54 km	30 May – 10 August	2 days earlier
Wiesbaden	68 km	30 May – 14 August	2 days earlier
Frankfurt	71 km	4 June – 8 August	3 days later
Stuttgart	94 km	5 June – 30 July	4 days later
Saarbrücken	111 km	3 June – 9 August	2 days later
Strasbourg	115 km	1 June – 11 August	same day

Where to buy watermelon plants and seeds near Mannheim

Buy plants ready to set out from 1 June to 11 August (from 11 May to 11 August for an unheated greenhouse); seed for raising your own is sown from 13 April to 14 July. Within 15 km of Mannheim OpenStreetMap lists 30 garden centres, 3 farm-supply shops, 17 plant nurseries, 24 markets and 50 farm shops (collected 28 October 2026).

Stadtteilmarkt Gartenstadt — market
Fri 07:00–13:30 · 5 km · ep-ma.de
Stadtteilmarkt Franklin — market
Wed 07:00–13:30; Fri 12:00–18:00 · 6 km · ep-ma.de
Stadtteilmarkt Wallstadt — market
Thu 07:00–13:30 · 6 km · ep-ma.de
Stadtteilmarkt Schönau — market
Wed, Sat 07:00–13:30 · 6 km · ep-ma.de

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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