When to plant watermelons in Karlsruhe: 30 May – 10 August

In Karlsruhe, watermelon: sow for seedlings from 11 April to 13 July; plant into a greenhouse from 9 May to 10 August; plant out into open ground from 30 May to 10 August.

Watermelon in Karlsruhe: soil, season and weather

In Karlsruhe the soil, not frost, sets the date: the last frost is over around 5 April, but the top 7 cm of soil reaches 18 °C — the minimum on the watermelon card — only around 30 May, 55 days later.

Last spring frost	5 April
Top 7 cm of soil at 18 °C	30 May, 55 days after the last frost
Into an unheated greenhouse	9 May – 10 August; May outside: 9.7 °C at night, 19.8 °C by day; card 18–35 °C
First autumn frost	19 November, 173 days after the start
Days in the bed to the first harvest (card)	59
First harvest, if planted in this window	28 July – 8 October
Days left for picking	114
Daylight	14:38 on 2 May, 15:51 on 30 May
Watering outdoors when fruiting (card)	every 5 days; the driest month, August, has 10 rainy days

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

Watermelon in Karlsruhe: 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 Karlsruhe during the watermelon season

No month of the season averages above the watermelon card's 18–35 °C by day; the warmest, August, averages 26.4 °C. Months that stay below 18 °C even by day on average: October (16.5 °C) and November (9.6 °C). Nights average below 18 °C in every month of the season, from 3.4 °C to 16.1 °C.

Month	Day, °C	Night, °C	Rain, mm	Rainy days	Daylight on the 15th
May	19.8	9.7	82	13	15:16
June	25.2	14.8	71	11	16:11
July	26.2	15.8	63	11	15:49
August	26.4	16.1	54	10	14:26
September	22	12.4	62	10	12:39
October	16.5	8.5	80	13	10:52
November	9.6	3.4	70	13	9:11

ERA5 2016–2025, Open-Meteo

Watermelon in nearby cities

1 of the nearest cities share Karlsruhe's date.

City	Distance	Date	Difference
Mannheim	54 km	1 June – 11 August	2 days later
Stuttgart	62 km	5 June – 30 July	6 days later
Strasbourg	68 km	1 June – 11 August	2 days later
Saarbrücken	106 km	3 June – 9 August	4 days later
Wiesbaden	120 km	30 May – 14 August	same day
Freiburg im Breisgau	120 km	4 June – 7 August	5 days later

Where to buy watermelon plants and seeds near Karlsruhe

Buy plants ready to set out from 30 May to 10 August (from 9 May to 10 August for an unheated greenhouse); seed for raising your own is sown from 11 April to 13 July. Within 15 km of Karlsruhe OpenStreetMap lists 25 garden centres, 3 farm-supply shops, 18 plant nurseries, 23 markets and 59 farm shops (collected 28 October 2026).

Wochenmarkt Neureut — market
Fri 07:30–13:30 · 4 km · karlsruhe.de
Wochenmarkt Waldstadt — market
Wed, Fri 09:00–17:00; Sat 07:00–14:00 · 4 km · karlsruhe.de
Wochenmarkt Rüppurr — market
Wed, Sat 07:30+ · 4 km · karlsruhe.de
Wochenmarkt Stephanplatz — market
Mon, Wed, Fri 07:30–14:00; public holidays closed · 1 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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