When to plant tomatoes in Idaho Falls: 18 May – 24 June

In Idaho Falls, tomato: sow for seedlings from 6 March to 3 May; plant into a greenhouse from 27 April to 24 June; plant out into open ground from 18 May to 24 June. For plants and seeds, the places nearby include Town and Country Gardens (garden centre, 7 km) and R & D Wholesale Nursery (garden centre, 8 km); addresses and opening hours are below.

Tomato in Idaho Falls: soil, season and weather

In Idaho Falls frost, not soil, sets the date: the top 7 cm of soil warms to 15 °C — the minimum on the tomato card — around 13 May, 2 days after the last frost on 11 May, so planting waits only for the week after that frost.

Last spring frost	11 May
Top 7 cm of soil at 15 °C	13 May, 2 days after the last frost
Into an unheated greenhouse	27 April – 24 June; April outside: 0.6 °C at night, 14.4 °C by day; card 16–27 °C
First autumn frost	14 October, 149 days after the start
Days in the bed to the first harvest (card)	70
First harvest, if planted in this window	27 July – 2 September
Days left for picking	79
Daylight	12:28 on 27 March, 14:47 on 18 May
Watering outdoors when fruiting (card)	every 3 days; the driest month, July, has 1 rainy day

Tomato in Idaho Falls: care after planting

Planted on 18 May: in the first weeks water every 4 days.

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

18 May — feed: balanced (NPK)
15 June — 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 Idaho Falls during the tomato season

Days average above the tomato card's 16–27 °C in June (27.3 °C), July (32.9 °C) and August (30.9 °C). Months that stay below 16 °C even by day on average: October (15.3 °C). Nights average below 16 °C in every month of the season, from 2.4 °C to 15.7 °C.

Month	Day, °C	Night, °C	Rain, mm	Rainy days	Daylight on the 15th
May	20.6	5.5	43	9	14:41
June	27.3	11.2	21	5	15:24
July	32.9	15.7	5	1	15:07
August	30.9	14.2	14	3	14:00
September	25.2	9.5	27	5	12:33
October	15.3	2.4	36	7	11:05

ERA5 2016–2025, Open-Meteo

Tomato in nearby cities

Around Idaho Falls, Boise is 21 days earlier and Helena 19 days later.

City	Distance	Date	Difference
Salt Lake City	305 km	7 May – 6 July	11 days earlier
Boise	336 km	27 April – 7 July	21 days earlier
Helena	345 km	6 June – 13 June	19 days later
Billings	377 km	11 May – 24 June	7 days earlier
Missoula	406 km	3 June – 16 June	16 days later
Elko	425 km	15 May – 23 June	3 days earlier

Where to buy tomato plants and seeds near Idaho Falls

Buy plants ready to set out from 18 May to 24 June (from 27 April to 24 June for an unheated greenhouse); seed for raising your own is sown from 6 March to 3 May. Within 15 km of Idaho Falls OpenStreetMap lists 4 garden centres, 3 farm-supply shops, 2 plant nurseries, 2 markets and 1 farm shop (collected 28 October 2026).

Town and Country Gardens — garden centre
South Yellowstone Highway 5800, 83402 Idaho Falls · 7 km · tcgardens.com
R & D Wholesale Nursery — garden centre
West Heritage Circle 2312, 83402 Idaho Falls · 8 km
Siems Enterprises LLC — farm supply
Mon, Thu, Fri 08:00–17:00; Tue 08:00–16:15; Wed 08:00–15:00; Sat 09:00–12:00 · 15 km
Itty Bitty Farms — farm shop
East Lincoln Road 5229, 83401-5769 Idaho Falls · 8 km · ittybittyfarmstore.com

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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