When to plant crocuses in Flagstaff: 21 September – end of December

In Flagstaff, crocus: plant from 21 September to the end of 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.

The average daily temperature here falls below 0 °C only in January; the sources go no later than December. Sources: Iowa State University Extension, Wisconsin Horticulture Extension, UNH Extension, RHS, how the ground freezes (NRC Canada, CBD-26).

Crocus in Flagstaff: soil, season and weather

Nights then average below 0 °C in December–March; the coldest, January, averages -5 °C.

Planting	21 September – end of December
First autumn frost	21 October
Coldest nights	January, -5 °C
Soil back at 1 °C in spring	18 January
Daylight	12:13 on 21 September
Daylight at the winter solstice	9:47

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

Crocus in Flagstaff: 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 Flagstaff the average daily temperature stays at 10 °C or lower for about 24 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

All the nearest cities on our list plant crocus later than Flagstaff; the closest date is in Santa Fe (United States), 5 days later.

City	Distance	Date	Difference
Las Vegas	336 km	by 12 November	52 days later
Albuquerque	452 km	10 October – end of December	19 days later
Grand Junction	512 km	27 September – 7 December	6 days later
Santa Fe (United States)	518 km	26 September – 11 December	5 days later
Las Cruces	550 km	by 25 October	34 days later
Ciudad Juárez	619 km	by 5 November	45 days later

Where to buy crocus for planting in Flagstaff

Planting stock goes into the ground from 21 September to the end of December; buy it before that. Within 15 km of Flagstaff OpenStreetMap lists 1 plant nursery and 1 market (collected 28 October 2026).

Sprouts Farmers Market — market
South Riordan Ranch Street 1540, 86001 Flagstaff · Mon–Sun 07:00–22:00 · 4 km · sprouts.com
Viola's Flower Garden — plant nursery
8 km

Questions