When to plant tomatoes in San Juan: 29 August – 28 February

In San Juan, tomato: sow for seedlings from 17 June to 7 January; plant into a greenhouse from 8 August to 28 February; plant out into open ground from 29 August to 28 February. For plants and seeds, the places nearby include Vivero Regalería Verde (garden centre, 2 km) and Vivero Yamanouchi (garden centre, 2 km); addresses and opening hours are below.

Tomato in San Juan: soil, season and weather

In San Juan the soil, not frost, sets the date: the last frost is over around 27 July, but the top 7 cm of soil reaches 15 °C — the minimum on the tomato card — only around 29 August, 33 days later.

Last spring frost	27 July
Top 7 cm of soil at 15 °C	29 August, 33 days after the last frost
Into an unheated greenhouse	8 August – 28 February; August outside: 5.9 °C at night, 19.9 °C by day; card 16–27 °C
First autumn frost	19 June, 295 days after the start
Days in the bed to the first harvest (card)	70
First harvest, if planted in this window	7 November – 8 May
Days left for picking	225
Daylight	10:11 on 8 July, 11:21 on 29 August
Watering outdoors when fruiting (card)	every 3 days; the driest month, September, has 1 rainy day

Tomato in San Juan: care after planting

Planted on 29 August: in the first weeks water every 4 days.

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

29 August — feed: balanced (NPK)
26 September — feed: nitrogen

Pests and diseases of tomato 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 San Juan during the tomato season

Days average above the tomato card's 16–27 °C in October–March (27.4–34.2 °C). Months that stay below 16 °C even by day on average: June (15.4 °C). Nights average below 16 °C in April–June and August–October (4–13.1 °C).

Month	Day, °C	Night, °C	Rain, mm	Rainy days	Daylight on the 15th
August	19.9	5.9	11	1	10:57
September	23.7	9.3	4	1	11:52
October	27.4	13.1	15	2	12:50
November	31.7	17.8	5	1	13:43
December	34	20.3	14	3	14:11
January	34.2	21.8	27	5	13:59
February	33.3	20.9	15	3	13:12
March	30	17.8	17	3	12:19
April	24.7	13.1	9	2	11:20
May	19.1	8.3	7	2	10:32
June	15.4	4	4	1	10:06

ERA5 2016–2025, Open-Meteo

Tomato in nearby cities

Around San Juan, La Rioja is 22 days earlier and Valparaíso 28 days later.

City	Distance	Date	Difference
Mendoza	153 km	9 September – 25 February	11 days later
San Luis	284 km	31 August – 2 March	2 days later
La Rioja	286 km	7 August – 23 February	22 days earlier
Santiago	292 km	23 September – 26 February	25 days later
Valparaíso	335 km	from 26 September	28 days later
San Rafael	343 km	11 September – 13 February	13 days later

Where to buy tomato plants and seeds near San Juan

Buy plants ready to set out from 29 August to 28 February (from 8 August to 28 February for an unheated greenhouse); seed for raising your own is sown from 17 June to 7 January. Within 15 km of San Juan OpenStreetMap lists 9 garden centres, 5 farm-supply shops, 3 plant nurseries and 6 markets (collected 27 October 2026).

Vivero Regalería Verde — garden centre
Lateral de Circunvalación 899 (S), 5400 San Juan · 2 km · vivero-regaleria-verde.negocio.site
Vivero Yamanouchi — garden centre
Tucumán 1111 (N), J5400EKW San Juan · Mon–Sat 09:00–13:00, 16:00–20:00 · 2 km
INSEMI — plant nursery
Sargento Cabral 3671 (O), 5407 Marquesado · 8 km
Fedemi — farm supply
25 de Mayo 1272 (E), J5400AGZ San Juan · 2 km · fedemi.com.ar

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