GreenlyWhen to plant watermelons in Castellón de la Plana: from 14 April
In Castellón de la Plana, watermelon: sow for seedlings from 24 February; plant into a greenhouse from 24 March; plant out into open ground from 14 April. There is no autumn frost here, so the frost dates set no end to the window.
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Watermelon in Castellón de la Plana: soil, season and weather
In Castellón de la Plana the soil, not frost, sets the date: the last frost is over around 12 January, but the top 7 cm of soil reaches 18 °C — the minimum on the watermelon card — only around 14 April, 92 days later. Castellón de la Plana has no autumn frost in the median year, so frost does not end the season.
| Last spring frost | 12 January |
|---|---|
| Top 7 cm of soil at 18 °C | 14 April, 92 days after the last frost |
| Into an unheated greenhouse | from 24 March; March outside: 8.9 °C at night, 17.6 °C by day; card 18–35 °C |
| Days in the bed to the first harvest (card) | 59 |
| First harvest, if planted in this window | from 12 June |
| Daylight | 11:59 on 17 March, 13:12 on 14 April |
| Watering outdoors when fruiting (card) | every 5 days; the driest month, July, has 2 rainy days |
The same dates in Castellón de la Plana hold for Cucumber, Bell Pepper, Eggplant, Zucchini and Pumpkin.
Watermelon in Castellón de la Plana: care after planting
Planted on 14 April: in the first weeks water every 5 days.
Feeding, by the card’s schedule from that day:
- 14 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 Castellón de la Plana during the watermelon season
No month of the season averages above the watermelon card's 18–35 °C by day; the warmest, August, averages 30 °C. Nights average below 18 °C in April (10.8 °C) and May (14.5 °C).
| Month | Day, °C | Night, °C | Rain, mm | Rainy days | Daylight on the 15th |
|---|---|---|---|---|---|
| April | 19.3 | 10.8 | 32 | 6 | 13:15 |
| May | 22.8 | 14.5 | 26 | 5 | 14:22 |
| June | 27 | 19.2 | 19 | 3 | 15:00 |
| July | 29.4 | 22 | 15 | 2 | 14:45 |
| August | 30 | 22.5 | 16 | 3 | 13:47 |
| September | 26.9 | 19.3 | 48 | 6 | 12:30 |
ERA5 2016–2025, Open-Meteo
Watermelon in nearby cities
All the nearest cities on our list plant watermelon later than Castellón de la Plana; the closest date is in Valencia, 8 days later.
Where to buy watermelon plants and seeds near Castellón de la Plana
Buy plants ready to set out from 14 April (from 24 March for an unheated greenhouse); seed for raising your own is sown from 24 February. Within 15 km of Castellón de la Plana OpenStreetMap lists 3 garden centres, 1 farm-supply shop and 8 markets (collected 27 October 2026).
- Mercat Municipal — market
Carrer de La Tanda 52, 12530 Borriana / Burriana · Sat, Mon–Fri 09:00–13:00; Fri 17:00–20:30 · 12 km - la Llotja — market
Moll de la Costa* 1, 12530 Borriana / Burriana · 14 km - Mercat Central — market
Plaça Major, 12001 Castelló de la Plana · 1 km - Mercat de Les Alqueries — market
Vía Augusta, 12539 les Alqueries / Alquerías del Niño Perdido · 12 km
Places: © OpenStreetMap contributors, ODbL.
- How to grow watermelon
- All frost dates and weather of Castellón de la Plana
- Shops and markets: Castellón de la Plana
- Selling a surplus in Spain
- Moon planting calendar for November 2026
- How we calculate the dates
Questions
When to plant watermelons in Castellón de la Plana?
In Castellón de la Plana, watermelon: sow for seedlings from 24 February; plant into a greenhouse from 24 March; plant out into open ground from 14 April. There is no autumn frost here, so the frost dates set no end to the window.
When to sow watermelons for seedlings in Castellón de la Plana?
Sow for seedlings from 24 February.
