When to plant watermelons in Rennes: 1 June – 19 August

In Rennes, watermelon: sow for seedlings from 13 April to 22 July; plant into a greenhouse from 11 May to 19 August; plant out into open ground from 1 June to 19 August.

Watermelon in Rennes: soil, season and weather

In Rennes the soil, not frost, sets the date: the last frost is over around 12 March, but the top 7 cm of soil reaches 18 °C — the minimum on the watermelon card — only around 1 June, 81 days later.

Last spring frost	12 March
Top 7 cm of soil at 18 °C	1 June, 81 days after the last frost
Into an unheated greenhouse	11 May – 19 August; May outside: 9.4 °C at night, 19.1 °C by day; card 18–35 °C
First autumn frost	28 November, 180 days after the start
Days in the bed to the first harvest (card)	59
First harvest, if planted in this window	30 July – 17 October
Days left for picking	121
Daylight	14:39 on 4 May, 15:47 on 1 June
Watering outdoors when fruiting (card)	every 5 days; the driest month, August, has 9 rainy days

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

Watermelon in Rennes: 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 Rennes during the watermelon season

No month of the season averages above the watermelon card's 18–35 °C by day; the warmest, August, averages 24.4 °C. Months that stay below 18 °C even by day on average: October (17.4 °C) and November (12.4 °C). Nights average below 18 °C in every month of the season, from 6.1 °C to 14.4 °C.

Month	Day, °C	Night, °C	Rain, mm	Rainy days	Daylight on the 15th
June	22.8	12.9	83	11	16:02
July	24.3	14.3	50	8	15:41
August	24.4	14.4	48	9	14:21
September	21.5	12.4	58	9	12:38
October	17.4	9.8	87	12	10:54
November	12.4	6.1	78	12	9:17

ERA5 2016–2025, Open-Meteo

Watermelon in nearby cities

Around Rennes, Nantes is 4 days earlier and Caen 14 days later.

City	Distance	Date	Difference
Nantes	99 km	28 May – 20 August	4 days earlier
Angers	110 km	28 May – 18 August	4 days earlier
Le Mans	140 km	31 May – 15 August	1 day earlier
Caen	154 km	15 June – 26 August	14 days later
Quimper	180 km	15 June – 30 August	14 days later
Tours	194 km	31 May – 18 August	1 day earlier

Where to buy watermelon plants and seeds near Rennes

Buy plants ready to set out from 1 June to 19 August (from 11 May to 19 August for an unheated greenhouse); seed for raising your own is sown from 13 April to 22 July. Within 15 km of Rennes OpenStreetMap lists 21 garden centres, 5 farm-supply shops, 3 plant nurseries, 41 markets and 19 farm shops (collected 20 October 2026).

Marché Bio — market
Tue 12:00–19:00 · 11 km · ville-bruz.fr
Marché alimentaire — market
Place de la Mairie, 35690 Acigné · Wed 07:00–13:00 · 11 km
Marché des Lices — market
Sat 07:45–13:30 · 0 km
Marché Saint-Germain — market
Wed 07:45–13:00 · 0 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