GreenlyWhen to plant watermelons in Leiria: from 12 May
In Leiria, watermelon: sow for seedlings from 24 March; plant into a greenhouse from 21 April; plant out into open ground from 12 May. There is no autumn frost here, so the frost dates set no end to the window.
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Watermelon in Leiria: soil, season and weather
In Leiria the soil, not frost, sets the date: the last frost is over around 22 January, but the top 7 cm of soil reaches 18 °C — the minimum on the watermelon card — only around 12 May, 110 days later. Leiria has no autumn frost in the median year, so frost does not end the season.
| Last spring frost | 22 January |
|---|---|
| Top 7 cm of soil at 18 °C | 12 May, 110 days after the last frost |
| Into an unheated greenhouse | from 21 April; April outside: 9.8 °C at night, 19.1 °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 10 July |
| Daylight | 13:11 on 14 April, 14:15 on 12 May |
| Watering outdoors when fruiting (card) | every 5 days; the driest month, August, has 1 rainy day |
The same dates in Leiria hold for Cucumber, Bell Pepper, Eggplant, Zucchini and Pumpkin.
Watermelon in Leiria: care after planting
Planted on 12 May: in the first weeks water every 5 days.
Feeding, by the card’s schedule from that day:
- 12 May — 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 Leiria during the watermelon season
No month of the season averages above the watermelon card's 18–35 °C by day; the warmest, August, averages 27.7 °C. Nights average below 18 °C in every month of the season, from 11.8 °C to 15.7 °C.
| Month | Day, °C | Night, °C | Rain, mm | Rainy days | Daylight on the 15th |
|---|---|---|---|---|---|
| May | 22 | 11.8 | 57 | 9 | 14:21 |
| June | 24.1 | 14.1 | 46 | 9 | 14:58 |
| July | 27 | 15.6 | 9 | 3 | 14:44 |
| August | 27.7 | 15.7 | 6 | 1 | 13:46 |
| September | 25.9 | 14.6 | 37 | 6 | 12:30 |
| October | 22.8 | 13.4 | 114 | 11 | 11:12 |
ERA5 2016–2025, Open-Meteo
Watermelon in nearby cities
Around Leiria, Castelo Branco is 12 days earlier and Viseu 15 days later.
Where to buy watermelon plants and seeds near Leiria
Buy plants ready to set out from 12 May (from 21 April for an unheated greenhouse); seed for raising your own is sown from 24 March. Within 15 km of Leiria OpenStreetMap lists 2 garden centres, 4 farm-supply shops, 2 plant nurseries and 8 markets (collected 27 October 2026).
- Crivila - Produção de Plantas, lda — plant nursery
8 km · crivila.com - Crivila — plant nursery
9 km - AgroMeirinhas — farm supply
15 km - Mercado Grossista de Leiria — market
5 km
Places: © OpenStreetMap contributors, ODbL.
- How to grow watermelon
- All frost dates and weather of Leiria
- Shops and markets: Leiria
- Selling a surplus in Portugal
- Moon planting calendar for November 2026
- How we calculate the dates
Questions
When to plant watermelons in Leiria?
In Leiria, watermelon: sow for seedlings from 24 March; plant into a greenhouse from 21 April; plant out into open ground from 12 May. There is no autumn frost here, so the frost dates set no end to the window.
When to sow watermelons for seedlings in Leiria?
Sow for seedlings from 24 March.
