When to plant crocuses in Bismarck: 15 September – 4 November

In Bismarck, crocus: plant from 15 September to about 4 November.

Bulbs are best planted early in the window: late-planted bulbs may flower later or less well. Late planting works only while the soil can be dug. Mulch after planting.

The date is about two weeks before the average daily temperature here falls below 0 °C (ten years of weather): an estimate, not the day the ground freezes, and a cold spell can freeze it earlier. Sources: Iowa State University Extension, Wisconsin Horticulture Extension, UNH Extension, RHS, how the ground freezes (NRC Canada, CBD-26).

Crocus in Bismarck: soil, season and weather

Nights then average below 0 °C in November–April; the coldest, January, averages -13.6 °C.

Planting	15 September – 4 November
First autumn frost	15 October
Coldest nights	January, -13.6 °C
Soil back at 1 °C in spring	24 March
Daylight	12:37 on 15 September
Daylight at the winter solstice	8:32

The same dates in Bismarck hold for Garlic, Tulip, Daffodil and Hyacinth.

Crocus in Bismarck: depth, winter cold, pests and pets

Plant Dutch crocuses (Crocus vernus) about 12 cm deep and 9 cm apart; smaller species go 7–10 cm deep (RHS).

In Bismarck the average daily temperature stays at 10 °C or lower for about 29 weeks a year (our estimate from ten years of monthly weather). For this bulb Wisconsin Horticulture Extension gives a cold period of 15–17 weeks at about 2–10 °C. The winter here gives that in the ground, so the bulbs need no pre-chilling.

Crocuses multiply on their own (they naturalise); in a lawn, hold off mowing until their leaves die back (RHS).

Birds, squirrels and rodents damage crocuses; planting under metal mesh may reduce losses (RHS). Spring crocus gives dogs and cats vomiting and diarrhoea; do not confuse it with autumn crocus (Colchicum), which is very toxic (Pet Poison Helpline).

Sources: RHS, Wisconsin Horticulture Extension, Pet Poison Helpline.

Crocus in nearby cities

Around Bismarck, Regina is 9 days earlier and Pierre 9 days later.

City	Distance	Date	Difference
Pierre	274 km	24 September – 19 November	9 days later
Fargo	303 km	16 September – 4 November	1 day later
Rapid City	360 km	12 September – 28 November	3 days earlier
Winnipeg	436 km	12 September – 26 October	3 days earlier
Sioux Falls	482 km	21 September – 16 November	6 days later
Regina	494 km	6 September – 22 October	9 days earlier

Where to buy crocus for planting in Bismarck

Planting stock goes into the ground from 15 September to about 4 November; buy it before that. 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

Questions