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When to plant crocuses in Fort Collins: 21 September – 5 December

In Fort Collins, crocus: plant from 21 September to about 5 December. For planting stock, the places nearby include Poudre Pet & Feed Supply (farm supply, 5 km) and Green Dog Farms (farm shop, 6 km); addresses and opening hours are below.

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 Fort Collins: soil, season and weather

Nights then average below 0 °C in November–March; the coldest, January, averages -8.2 °C.

Planting21 September – 5 December
First autumn frost21 October
Coldest nightsJanuary, -8.2 °C
Soil back at 1 °C in spring12 February
Daylight12:14 on 21 September
Daylight at the winter solstice9:16

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

Crocus in Fort Collins: 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 Fort Collins the average daily temperature stays at 10 °C or lower for about 26 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 Fort Collins, Rapid City is 9 days earlier and Dodge City 8 days later.

CityDistanceDateDifference
Cheyenne69 km13 September – 4 December8 days earlier
Denver90 km15 September – 14 December6 days earlier
Pueblo258 km28 September – end of December7 days later
Grand Junction340 km27 September – 7 December6 days later
Rapid City420 km12 September – 28 November9 days earlier
Dodge City534 km29 September – end of December8 days later

Where to buy crocus for planting in Fort Collins

Planting stock goes into the ground from 21 September to about 5 December; buy it before that. Within 15 km of Fort Collins OpenStreetMap lists 10 garden centres, 4 farm-supply shops, 2 plant nurseries, 3 markets and 6 farm shops (collected 28 October 2026).

Places: © OpenStreetMap contributors, ODbL.

Questions

When to plant crocuses in Fort Collins?

In Fort Collins, crocus: plant from 21 September to about 5 December. 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.

When is the last spring frost in Fort Collins?

Last spring frost around 25 April, first autumn frost around 21 October.

Other crops in Fort Collins, with their dates