When to plant watermelons in Jaca: 19 June – 22 July

In Jaca, watermelon: sow for seedlings from 1 May to 24 June; plant into a greenhouse from 29 May to 22 July; plant out into open ground from 19 June to 22 July.

Watermelon in Jaca: soil, season and weather

In Jaca the soil, not frost, sets the date: the last frost is over around 3 May, but the top 7 cm of soil reaches 18 °C — the minimum on the watermelon card — only around 19 June, 47 days later.

Last spring frost	3 May
Top 7 cm of soil at 18 °C	19 June, 47 days after the last frost
Into an unheated greenhouse	29 May – 22 July; May outside: 5.1 °C at night, 17.4 °C by day; card 18–35 °C
First autumn frost	31 October, 134 days after the start
Days in the bed to the first harvest (card)	59
First harvest, if planted in this window	17 August – 19 September
Days left for picking	75
Daylight	14:49 on 22 May, 15:18 on 19 June
Watering outdoors when fruiting (card)	every 5 days; the driest month, July, has 6 rainy days

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

Watermelon in Jaca: care after planting

Planted on 19 June: in the first weeks water every 5 days.

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

19 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 Jaca during the watermelon season

No month of the season averages above the watermelon card's 18–35 °C by day; the warmest, August, averages 26.8 °C. Months that stay below 18 °C even by day on average: October (16.6 °C). Nights average below 18 °C in every month of the season, from 5.4 °C to 12.8 °C.

Month	Day, °C	Night, °C	Rain, mm	Rainy days	Daylight on the 15th
June	22.8	10	72	11	15:17
July	26.4	12.5	39	6	15:01
August	26.8	12.8	49	6	13:57
September	20.9	8.7	75	8	12:32
October	16.6	5.4	90	10	11:07

ERA5 2016–2025, Open-Meteo

Watermelon in nearby cities

All the nearest cities on our list plant watermelon earlier than Jaca; the closest date is in Pau, 17 days earlier.

City	Distance	Date	Difference
Huesca	47 km	23 May – 17 August	27 days earlier
Pau	86 km	2 June – 25 August	17 days earlier
Pamplona	94 km	1 June – 21 August	18 days earlier
Tudela	102 km	6 May – 28 August	44 days earlier
Zaragoza	104 km	30 April – 10 September	50 days earlier
Bayonne	129 km	28 May – 7 September	22 days earlier

Where to buy watermelon plants and seeds near Jaca

Buy plants ready to set out from 19 June to 22 July (from 29 May to 22 July for an unheated greenhouse); seed for raising your own is sown from 1 May to 24 June. Within 15 km of Jaca OpenStreetMap lists 1 farm shop (collected 28 October 2026).

Comercial Agraria El Llano — farm shop
2 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