When to plant watermelons in Santa Rosa: 22 October – 3 March

In Santa Rosa, watermelon: sow for seedlings from 3 September to 4 February; plant into a greenhouse from 1 October to 3 March; plant out into open ground from 22 October to 3 March. For plants and seeds, the places nearby include Vivero Forestal Provincial Santa Rosa (plant nursery, 3 km); addresses and opening hours are below.

Watermelon in Santa Rosa: soil, season and weather

In Santa Rosa the soil, not frost, sets the date: the last frost is over around 25 August, but the top 7 cm of soil reaches 18 °C — the minimum on the watermelon card — only around 22 October, 58 days later.

Last spring frost	25 August
Top 7 cm of soil at 18 °C	22 October, 58 days after the last frost
Into an unheated greenhouse	1 October – 3 March; October outside: 10.7 °C at night, 22.4 °C by day; card 18–35 °C
First autumn frost	12 June, 234 days after the start
Days in the bed to the first harvest (card)	59
First harvest, if planted in this window	20 December – 1 May
Days left for picking	175
Daylight	12:10 on 24 September, 13:15 on 22 October
Watering outdoors when fruiting (card)	every 5 days; the driest month, June, has 3 rainy days

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

Watermelon in Santa Rosa: care after planting

Planted on 22 October: in the first weeks water every 5 days.

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

22 October — 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 Santa Rosa during the watermelon season

No month of the season averages above the watermelon card's 18–35 °C by day; the warmest, January, averages 30.5 °C. Months that stay below 18 °C even by day on average: May (16.5 °C) and June (13.6 °C). Nights average below 18 °C in February–June and October–December (4.6–17.7 °C).

Month	Day, °C	Night, °C	Rain, mm	Rainy days	Daylight on the 15th
October	22.4	10.7	66	7	12:59
November	26.3	14.3	75	8	14:04
December	29.6	17	64	7	14:39
January	30.5	18.8	59	8	14:23
February	29	17.7	77	7	13:26
March	25.6	15.2	90	8	12:22
April	21.1	11.7	76	7	11:10
May	16.5	7.7	29	5	10:12
June	13.6	4.6	17	3	9:40

ERA5 2016–2025, Open-Meteo

Watermelon in nearby cities

Around Santa Rosa, San Rafael is 30 days earlier and Bahía Blanca 14 days later.

City	Distance	Date	Difference
Bahía Blanca	293 km	5 November – 5 March	14 days later
Río Cuarto	388 km	29 September – 4 March	23 days earlier
San Luis	414 km	25 September – 13 March	27 days earlier
Neuquén	421 km	17 October – 28 February	5 days earlier
San Rafael	428 km	22 September – 24 February	30 days earlier
Rosario	527 km	29 September – 5 March	23 days earlier

Where to buy watermelon plants and seeds near Santa Rosa

Buy plants ready to set out from 22 October to 3 March (from 1 October to 3 March for an unheated greenhouse); seed for raising your own is sown from 3 September to 4 February. Within 15 km of Santa Rosa OpenStreetMap lists 2 garden centres, 4 farm-supply shops, 2 plant nurseries and 1 market (collected 28 October 2026).

Vivero Dadan — plant nursery
4 km
Agrotec S.A. — farm supply · sells seed
3 km · agrotecsa.com.ar
Tierramía Insumos Agropecuarios — farm supply
3 km
Vivero Forestal Provincial Santa Rosa — plant nursery
Eva Perón Este, L6300 Santa Rosa · Mon–Fri 08:00–12:30 · 3 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.

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