When to plant pumpkins in Helena: 3 July – 20 July

In Helena, pumpkin: sow for seedlings from 1 May to 8 June; plant into a greenhouse from 12 June to 20 July; plant out into open ground from 3 July to 20 July.

Pumpkin in Helena: soil, season and weather

In Helena the soil, not frost, sets the date: the last frost is over around 19 May, but the top 7 cm of soil reaches 18 °C — the minimum on the pumpkin card — only around 3 July, 45 days later. Planting out on 3 July leaves 92 days to the first autumn frost on 3 October, only 17 more than the card's 75 days to the first harvest; an unheated greenhouse, three weeks earlier, would add 21.

Last spring frost	19 May
Top 7 cm of soil at 18 °C	3 July, 45 days after the last frost
First autumn frost	3 October, 92 days after the start
Days in the bed to the first harvest (card)	75
First harvest, if planted in this window	16 September – 3 October
Days left for picking	17
Daylight	15:16 on 22 May, 15:45 on 3 July
Watering outdoors when fruiting (card)	every 5 days; the driest month, July, has 6 rainy days

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

Pumpkin in Helena: care after planting

Planted on 3 July: in the first weeks water every 4 days.

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

24 July — 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 Helena during the pumpkin season

About 137 mm of rain falls in the season; July is the driest month (23 mm) and October the wettest (46 mm).

Month	Day, °C	Night, °C	Rain, mm	Rainy days	Daylight on the 15th
July	27.3	12.1	23	6	15:29
August	26.5	11.5	28	5	14:14
September	21.1	7.4	40	7	12:36
October	12	0.6	46	9	10:58

ERA5 2016–2025, Open-Meteo

Pumpkin in nearby cities

All the nearest cities on our list plant pumpkin earlier than Helena; the closest date is in Missoula, 3 days earlier.

City	Distance	Date	Difference
Missoula	155 km	30 June – 23 July	3 days earlier
Billings	287 km	2 June – 19 June	31 days earlier
Idaho Falls	345 km	4 June – 19 June	29 days earlier
Spokane	425 km	22 May – 20 June	42 days earlier
Boise	466 km	7 May – 2 July	57 days earlier
Calgary	517 km	18 June – 18 July	15 days earlier

Where to buy pumpkin plants and seeds near Helena

Buy plants ready to set out from 3 July to 20 July (from 12 June to 20 July for an unheated greenhouse); seed for raising your own is sown from 1 May to 8 June. Within 15 km of Helena OpenStreetMap lists 2 farm-supply shops and 6 plant nurseries (collected 28 October 2026).

Montana Nursery & Landscape Supply — plant nursery
7 km
Korpi Lawn and Landscape — plant nursery
7 km
Helena Farm Supply — farm supply
9 km
Agri Feeds & Fertilizer — farm supply
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