When to plant watermelons in Alcázar de San Juan: 30 April – 23 August

In Alcázar de San Juan, watermelon: sow for seedlings from 12 March to 26 July; plant into a greenhouse from 9 April to 23 August; plant out into open ground from 30 April to 23 August.

Watermelon in Alcázar de San Juan: soil, season and weather

In Alcázar de San Juan the soil, not frost, sets the date: the last frost is over around 15 March, but the top 7 cm of soil reaches 18 °C — the minimum on the watermelon card — only around 30 April, 46 days later.

Last spring frost	15 March
Top 7 cm of soil at 18 °C	30 April, 46 days after the last frost
Into an unheated greenhouse	9 April – 23 August; April outside: 7.6 °C at night, 19.1 °C by day; card 18–35 °C
First autumn frost	2 December, 216 days after the start
Days in the bed to the first harvest (card)	59
First harvest, if planted in this window	28 June – 21 October
Days left for picking	157
Daylight	12:40 on 2 April, 13:48 on 30 April
Watering outdoors when fruiting (card)	every 5 days; the driest month, July, has 1 rainy day

The same dates in Alcázar de San Juan hold for Cucumber, Bell Pepper, Eggplant, Zucchini and Pumpkin.

Watermelon in Alcázar de San Juan: care after planting

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

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

30 April — 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 Alcázar de San Juan during the watermelon season

No month of the season averages above the watermelon card's 18–35 °C by day; the warmest, July, averages 35 °C. Months that stay below 18 °C even by day on average: November (14.6 °C) and December (11.5 °C). Nights average below 18 °C in April–June and September–December (3–17.1 °C).

Month	Day, °C	Night, °C	Rain, mm	Rainy days	Daylight on the 15th
April	19.1	7.6	57	10	13:13
May	24.7	11.9	29	5	14:19
June	30.6	17.1	19	4	14:56
July	35	20.6	3	1	14:42
August	34.2	20.4	8	1	13:45
September	27.7	15.5	25	4	12:29
October	22.4	11.4	52	7	11:13
November	14.6	5.7	45	8	10:02
December	11.5	3	36	6	9:25

ERA5 2016–2025, Open-Meteo

Watermelon in nearby cities

All the nearest cities on our list plant watermelon later than Alcázar de San Juan; the closest date is in Ciudad Real, 7 days later.

City	Distance	Date	Difference
Ciudad Real	76 km	7 May – 19 August	7 days later
Toledo	88 km	11 May – 27 August	11 days later
Cuenca (Spain)	119 km	14 May – 4 August	14 days later
Madrid	122 km	14 May – 18 August	14 days later
Albacete	125 km	12 May – 17 August	12 days later
Guadalajara (Spain)	138 km	17 May – 15 August	17 days later

Where to buy watermelon plants and seeds near Alcázar de San Juan

Buy plants ready to set out from 30 April to 23 August (from 9 April to 23 August for an unheated greenhouse); seed for raising your own is sown from 12 March to 26 July. Within 15 km of Alcázar de San Juan OpenStreetMap lists 1 garden centre and 1 market (collected 28 October 2026).

Fertyvicam Sl — garden centre
6 km
Mercado Municipal — market
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