When to plant pumpkins in Bismarck: 31 May – 20 June

In Bismarck, pumpkin: sow for seedlings from 29 March to 9 May; plant into a greenhouse from 10 May to 20 June; plant out into open ground from 31 May to 20 June.

Pumpkin in Bismarck: soil, season and weather

In Bismarck the soil, not frost, sets the date: the last frost is over around 1 May, but the top 7 cm of soil reaches 18 °C — the minimum on the pumpkin card — only around 31 May, 30 days later.

Last spring frost	1 May
Top 7 cm of soil at 18 °C	31 May, 30 days after the last frost
First autumn frost	15 October, 137 days after the start
Days in the bed to the first harvest (card)	75
First harvest, if planted in this window	14 August – 3 September
Days left for picking	62
Daylight	13:46 on 19 April, 15:34 on 31 May
Watering outdoors when fruiting (card)	every 5 days; the driest month, October, has 5 rainy days

The same dates in Bismarck hold for Cucumber, Bell Pepper, Eggplant, Zucchini and Watermelon.

Pumpkin in Bismarck: care after planting

Planted on 31 May: in the first weeks water every 4 days.

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

21 June — feed: nitrogen

Pests and diseases of pumpkin 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 Bismarck during the pumpkin season

About 366 mm of rain falls in the season; October is the driest month (44 mm) and June the wettest (69 mm).

Month	Day, °C	Night, °C	Rain, mm	Rainy days	Daylight on the 15th
May	20.2	7.4	67	10	15:01
June	26.6	14.1	69	9	15:51
July	29.1	17.2	63	8	15:31
August	27.6	15.8	68	8	14:15
September	23.4	11.8	55	7	12:37
October	13.7	3.6	44	5	10:58

ERA5 2016–2025, Open-Meteo

Pumpkin in nearby cities

Around Bismarck, Sioux Falls is 7 days earlier and Rapid City 6 days later.

City	Distance	Date	Difference
Pierre	274 km	25 May – 29 June	6 days earlier
Fargo	303 km	31 May – 21 June	same day
Grand Forks	303 km	5 June – 21 June	5 days later
Rapid City	360 km	6 June – 17 June	6 days later
Winnipeg	436 km	1 June – 17 June	1 day later
Sioux Falls	482 km	24 May – 26 June	7 days earlier

Where to buy pumpkin plants and seeds near Bismarck

Buy plants ready to set out from 31 May to 20 June (from 10 May to 20 June for an unheated greenhouse); seed for raising your own is sown from 29 March to 9 May. Within 15 km of Bismarck OpenStreetMap lists 1 garden centre and 1 market (collected 28 October 2026).

Bismarket — market
South Washington Street 318, 58504 Bismarck · Jun–Oct Sat 10:00–13:00 · 2 km · bismarket.com
Lowe's Plant Section — garden centre
4 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