When to plant tomatoes in Riverside: 24 February – 29 August

In Riverside, tomato: sow for seedlings from 13 December to 8 July; plant into a greenhouse from 3 February to 29 August; plant out into open ground from 24 February to 29 August. For plants and seeds, the places nearby include Milfelds Nursery (garden centre, 4 km) and Walmart Garden Center (garden centre, 13 km); addresses and opening hours are below.

Tomato in Riverside: soil, season and weather

In Riverside the soil, not frost, sets the date: the last frost is over around 12 January, but the top 7 cm of soil reaches 15 °C — the minimum on the tomato card — only around 24 February, 43 days later.

Last spring frost	12 January
Top 7 cm of soil at 15 °C	24 February, 43 days after the last frost
Into an unheated greenhouse	3 February – 29 August; February outside: 7.6 °C at night, 20.8 °C by day; card 16–27 °C
First autumn frost	19 December, 298 days after the start
Days in the bed to the first harvest (card)	70
First harvest, if planted in this window	5 May – 7 November
Days left for picking	228
Daylight	9:57 on 3 January, 11:16 on 24 February
Watering outdoors when fruiting (card)	every 3 days; the driest month, June, has 0 rainy days

Tomato in Riverside: care after planting

Planted on 24 February: in the first weeks water every 4 days.

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

24 February — feed: balanced (NPK)
24 March — 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 Riverside during the tomato season

Days average above the tomato card's 16–27 °C in May–October (27.2–35.7 °C). Nights average below 16 °C in February–June and October–December (7.6–15.4 °C).

Month	Day, °C	Night, °C	Rain, mm	Rainy days	Daylight on the 15th
February	20.8	7.6	66	6	10:58
March	21.5	9	67	9	11:56
April	25.8	11.3	19	3	13:01
May	27.2	13	9	3	13:55
June	31.9	15.4	1	0	14:24
July	35.1	18.1	2	0	14:13
August	35.7	18.9	6	1	13:27
September	33.6	17.9	14	2	12:25
October	29.8	14.6	13	3	11:22
November	24.8	10.5	35	3	10:25
December	20.3	7.8	69	5	9:55

ERA5 2016–2025, Open-Meteo

Tomato in nearby cities

Around Riverside, Phoenix is 13 days earlier and Santa Barbara 46 days later.

City	Distance	Date	Difference
Bakersfield	217 km	16 March – 24 August	20 days later
Santa Barbara	218 km	11 April – 25 August	46 days later
Ensenada	243 km	23 February – 24 August	1 day earlier
Las Vegas	321 km	13 March – 22 August	17 days later
Fresno	378 km	15 March – 15 August	19 days later
Phoenix	496 km	11 February – 8 September	13 days earlier

Where to buy tomato plants and seeds near Riverside

Buy plants ready to set out from 24 February to 29 August (from 3 February to 29 August for an unheated greenhouse); seed for raising your own is sown from 13 December to 8 July. Within 15 km of Riverside OpenStreetMap lists 4 garden centres, 30 plant nurseries, 7 markets and 10 farm shops (collected 28 October 2026).

Milfelds Nursery — garden centre
Adams Street 2550, 92504 Riverside · Mon–Fri 07:00–15:30 · 4 km · milfeldsnursery.com
Walmart Garden Center — garden centre
North McKinley Street 479, 92879 Corona · Mon–Sun 06:00–24:00 · 13 km · walmart.com
Victoria Grove Produce Market — market
Blackburn Road 12261, 92503 Riverside · sunrise–sunset · 11 km
Lake Mathews Market — market
Cajalco Road 17679, 92570 Perris · Mon–Sat 07:00–18:30 · 14 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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