When to plant watermelons in Colmar: 16 June – 8 August

In Colmar, watermelon: sow for seedlings from 28 April to 11 July; plant into a greenhouse from 26 May to 8 August; plant out into open ground from 16 June to 8 August. For plants and seeds, the places nearby include Trèfle vert (garden centre, 3 km) and Truffaut (garden centre, 5 km); addresses and opening hours are below.

Watermelon in Colmar: soil, season and weather

In Colmar the soil, not frost, sets the date: the last frost is over around 20 April, but the top 7 cm of soil reaches 18 °C — the minimum on the watermelon card — only around 16 June, 57 days later.

Last spring frost	20 April
Top 7 cm of soil at 18 °C	16 June, 57 days after the last frost
Into an unheated greenhouse	26 May – 8 August; May outside: 8 °C at night, 16.6 °C by day; card 18–35 °C
First autumn frost	17 November, 154 days after the start
Days in the bed to the first harvest (card)	59
First harvest, if planted in this window	14 August – 6 October
Days left for picking	95
Daylight	15:20 on 19 May, 16:02 on 16 June
Watering outdoors when fruiting (card)	every 5 days; the driest month, September, has 12 rainy days

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

Watermelon in Colmar: care after planting

Planted on 16 June: in the first weeks water every 5 days.

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

16 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 Colmar during the watermelon season

No month of the season averages above the watermelon card's 18–35 °C by day; the warmest, August, averages 23.2 °C. Months that stay below 18 °C even by day on average: October (14.4 °C) and November (8 °C). Nights average below 18 °C in every month of the season, from 2.3 °C to 14.1 °C.

Month	Day, °C	Night, °C	Rain, mm	Rainy days	Daylight on the 15th
June	21.8	12.9	102	15	16:02
July	23.1	13.9	77	13	15:41
August	23.2	14.1	81	13	14:21
September	18.9	10.7	69	12	12:38
October	14.4	7.2	82	12	10:54
November	8	2.3	92	14	9:17

ERA5 2016–2025, Open-Meteo

Watermelon in nearby cities

All the nearest cities on our list plant watermelon earlier than Colmar; the closest date is in Zurich, 5 days earlier.

City	Distance	Date	Difference
Mulhouse	37 km	1 June – 8 August	15 days earlier
Freiburg im Breisgau	38 km	4 June – 7 August	12 days earlier
Basel	60 km	5 June – 11 August	11 days earlier
Strasbourg	62 km	1 June – 11 August	15 days earlier
Nancy	110 km	3 June – 8 August	13 days earlier
Zurich	118 km	11 June – 7 August	5 days earlier

Where to buy watermelon plants and seeds near Colmar

Buy plants ready to set out from 16 June to 8 August (from 26 May to 8 August for an unheated greenhouse); seed for raising your own is sown from 28 April to 11 July. Within 15 km of Colmar OpenStreetMap lists 10 garden centres, 6 farm-supply shops, 1 plant nursery, 1 market and 8 farm shops (collected 27 October 2026).

Miel & Bois — farm shop · sells: honey
10 km
l'Eglantine de Bergheim, Confitures — farm shop
14 km
Truffaut — garden centre
Mon–Fri 09:30–12:30, Mon–Sat 14:00–19:00, Sat 09:30–19:00 · 5 km · truffaut.com
Trèfle vert — garden centre
Mon–Fri 09:00–12:00, 14:00–18:30; Sat 09:00–12:00, 14:00–18:00 · 3 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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