When to plant watermelons in La Rioja: 30 August – 5 March

In La Rioja, watermelon: sow for seedlings from 12 July to 6 February; plant into a greenhouse from 9 August to 5 March; plant out into open ground from 30 August to 5 March.

Watermelon in La Rioja: soil, season and weather

In La Rioja the soil, not frost, sets the date: the last frost is over around 17 July, but the top 7 cm of soil reaches 18 °C — the minimum on the watermelon card — only around 30 August, 44 days later.

Last spring frost	17 July
Top 7 cm of soil at 18 °C	30 August, 44 days after the last frost
Into an unheated greenhouse	9 August – 5 March; August outside: 8.7 °C at night, 22.3 °C by day; card 18–35 °C
First autumn frost	14 June, 289 days after the start
Days in the bed to the first harvest (card)	59
First harvest, if planted in this window	28 October – 3 May
Days left for picking	230
Daylight	10:45 on 2 August, 11:26 on 30 August
Watering outdoors when fruiting (card)	every 5 days; the driest month, August, has 1 rainy day

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

Watermelon in La Rioja: care after planting

Planted on 30 August: in the first weeks water every 5 days.

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

30 August — 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 La Rioja during the watermelon season

No month of the season averages above the watermelon card's 18–35 °C by day; the warmest, January, averages 34.7 °C. Months that stay below 18 °C even by day on average: June (17.2 °C). Nights average below 18 °C in April–June and August–October (7.1–15.8 °C).

Month	Day, °C	Night, °C	Rain, mm	Rainy days	Daylight on the 15th
August	22.3	8.7	4	1	11:03
September	26.7	12.3	9	1	11:53
October	29.6	15.8	39	4	12:46
November	33.2	19.6	39	5	13:35
December	34.4	21.5	77	7	14:01
January	34.7	22.7	130	9	13:49
February	32.8	21.8	74	9	13:07
March	30.1	19.6	76	7	12:18
April	25.4	15.6	44	6	11:24
May	20.6	11.1	22	4	10:40
June	17.2	7.1	8	2	10:16

ERA5 2016–2025, Open-Meteo

Watermelon in nearby cities

1 of the nearest cities share La Rioja's date.

City	Distance	Date	Difference
San Fernando del Valle de Catamarca	148 km	30 August – 19 March	same day
San Juan	286 km	18 September – 10 March	19 days later
San Miguel de Tucumán	331 km	from 15 September	16 days later
Córdoba	341 km	1 October – 5 March	32 days later
Copiapó	408 km	8 September – 14 March	9 days later
Mendoza	430 km	19 September – 7 March	20 days later

Where to buy watermelon plants and seeds near La Rioja

Buy plants ready to set out from 30 August to 5 March (from 9 August to 5 March for an unheated greenhouse); seed for raising your own is sown from 12 July to 6 February. Within 15 km of La Rioja OpenStreetMap lists 2 markets (collected 28 October 2026).

El Gato Negro — market
Lamadrid 401, 5300 La Rioja · 1 km
Boot Mini market — market
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.

Questions