When to plant tomatoes in Pierre: 9 May – 4 July

In Pierre, tomato: sow for seedlings from 25 February to 13 May; plant into a greenhouse from 18 April to 4 July; plant out into open ground from 9 May to 4 July.

Tomato in Pierre: soil, season and weather

In Pierre the soil, not frost, sets the date: the last frost is over around 26 April, but the top 7 cm of soil reaches 15 °C — the minimum on the tomato card — only around 9 May, 13 days later.

Last spring frost	26 April
Top 7 cm of soil at 15 °C	9 May, 13 days after the last frost
Into an unheated greenhouse	18 April – 4 July; April outside: 2 °C at night, 14.2 °C by day; card 16–27 °C
First autumn frost	24 October, 168 days after the start
Days in the bed to the first harvest (card)	70
First harvest, if planted in this window	18 July – 12 September
Days left for picking	98
Daylight	12:01 on 18 March, 14:32 on 9 May
Watering outdoors when fruiting (card)	every 3 days; the driest month, October, has 6 rainy days

Tomato in Pierre: care after planting

Planted on 9 May: in the first weeks water every 4 days.

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

9 May — feed: balanced (NPK)
6 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 Pierre during the tomato season

Days average above the tomato card's 16–27 °C in June (29.3 °C), July (31.7 °C) and August (30.2 °C). Nights average below 16 °C in May (9.9 °C), September (14.5 °C) and October (5.9 °C).

Month	Day, °C	Night, °C	Rain, mm	Rainy days	Daylight on the 15th
May	21.8	9.9	83	11	14:46
June	29.3	17	67	8	15:31
July	31.7	19.7	68	9	15:13
August	30.2	18.4	59	7	14:04
September	26.3	14.5	50	6	12:34
October	16.5	5.9	41	6	11:03

ERA5 2016–2025, Open-Meteo

Tomato in nearby cities

Around Pierre, Grand Island is 9 days earlier and Grand Forks 15 days later.

City	Distance	Date	Difference
Rapid City	233 km	20 May – 22 June	11 days later
Bismarck	274 km	22 May – 25 June	13 days later
Sioux Falls	302 km	11 May – 1 July	2 days later
Fargo	391 km	18 May – 26 June	9 days later
Grand Island	416 km	30 April – 7 July	9 days earlier
Grand Forks	467 km	24 May – 26 June	15 days later

Where to buy tomato plants and seeds near Pierre

Buy plants ready to set out from 9 May to 4 July (from 18 April to 4 July for an unheated greenhouse); seed for raising your own is sown from 25 February to 13 May. Within 15 km of Pierre OpenStreetMap lists 1 market (collected 28 October 2026).

The Alley Exchange — market
South Pierre Street 339, 57501 Pierre · 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.

Questions