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When to plant crocuses in Ulsan: 17 October – end of December

In Ulsan, crocus: plant from 17 October to the end of December. For planting stock, the places nearby include 조운어바웃플랜츠 (garden centre, 12 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 average daily temperature here stays above 0 °C all winter, and at least three months average 7 °C or less: our rule of thumb for the winter cold spring bulbs need. Sources: Iowa State University Extension, Wisconsin Horticulture Extension, UNH Extension, RHS.

Crocus in Ulsan: soil, season and weather

Nights then average below 0 °C in December–February; the coldest, January, averages -3.5 °C.

Planting17 October – end of December
First autumn frost16 November
Coldest nightsJanuary, -3.5 °C
Soil back at 1 °C in springalready in the first week of January
Daylight11:16 on 17 October
Daylight at the winter solstice9:45

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

Crocus in Ulsan: 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 Ulsan the average daily temperature stays at 10 °C or lower for about 19 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 Ulsan, Daejeon is 4 days earlier and Fukuoka 35 days later.

CityDistanceDateDifference
Busan47 km23 October – end of December6 days later
Daegu74 km22 October – end of December5 days later
Daejeon195 km13 October – 5 December4 days earlier
Jeonju198 km18 October – 17 December1 day later
Gwangju228 km24 October – end of December7 days later
Fukuoka239 kmby 21 November35 days later

Where to buy crocus for planting in Ulsan

Planting stock goes into the ground from 17 October to the end of December; buy it before that. Within 15 km of Ulsan OpenStreetMap lists 1 garden centre, 8 markets and 1 farm shop (collected 28 October 2026).

Places: © OpenStreetMap contributors, ODbL.

Questions

When to plant crocuses in Ulsan?

In Ulsan, crocus: plant from 17 October 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.

When is the last spring frost in Ulsan?

Last spring frost around 22 March, first autumn frost around 16 November.

Other crops in Ulsan, with their dates