When to plant tomatoes in Rapid City: 20 May – 22 June

In Rapid City, tomato: sow for seedlings from 8 March to 1 May; plant into a greenhouse from 29 April to 22 June; plant out into open ground from 20 May to 22 June.

Tomato in Rapid City: soil, season and weather

In Rapid City the soil, not frost, sets the date: the last frost is over around 7 May, but the top 7 cm of soil reaches 15 °C — the minimum on the tomato card — only around 20 May, 13 days later.

Last spring frost	7 May
Top 7 cm of soil at 15 °C	20 May, 13 days after the last frost
Into an unheated greenhouse	29 April – 22 June; April outside: 0.7 °C at night, 13.5 °C by day; card 16–27 °C
First autumn frost	12 October, 145 days after the start
Days in the bed to the first harvest (card)	70
First harvest, if planted in this window	29 July – 31 August
Days left for picking	75
Daylight	12:35 on 29 March, 14:55 on 20 May
Watering outdoors when fruiting (card)	every 3 days; the driest month, September, has 5 rainy days

Tomato in Rapid City: care after planting

Planted on 20 May: in the first weeks water every 4 days.

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

20 May — feed: balanced (NPK)
17 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 Rapid City during the tomato season

Days average above the tomato card's 16–27 °C in July (29.7 °C) and August (28.5 °C). Months that stay below 16 °C even by day on average: October (15.9 °C). Nights average below 16 °C in May, June and August–October (4.5–15.9 °C).

Month	Day, °C	Night, °C	Rain, mm	Rainy days	Daylight on the 15th
May	19	7.3	86	14	14:44
June	26.5	13.8	69	10	15:28
July	29.7	16.8	49	9	15:11
August	28.5	15.9	39	7	14:03
September	24.9	12.3	31	5	12:34
October	15.9	4.5	39	6	11:04

ERA5 2016–2025, Open-Meteo

Tomato in nearby cities

Around Rapid City, Denver is 12 days earlier and Cheyenne 5 days later.

City	Distance	Date	Difference
Pierre	233 km	9 May – 4 July	11 days earlier
Cheyenne	351 km	25 May – 23 June	5 days later
Bismarck	360 km	22 May – 25 June	2 days later
Fort Collins	420 km	14 May – 1 July	6 days earlier
Billings	457 km	11 May – 24 June	9 days earlier
Denver	503 km	8 May – 25 June	12 days earlier

Where to buy tomato plants and seeds near Rapid City

Buy plants ready to set out from 20 May to 22 June (from 29 April to 22 June for an unheated greenhouse); seed for raising your own is sown from 8 March to 1 May. Within 15 km of Rapid City OpenStreetMap lists 1 market (collected 29 October 2026).

Blackhills Farmers Market — market
East Omaha Street 245, 57701 Rapid City · Nov–Apr Sat 09:00–12:00; May–Oct Sat 08:00–13:00; Jul–Oct Wed 08:00–13:00 · 2 km · blackhillsfarmersmarket.org

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