When to plant crocuses in Invercargill: by 9 May

In Invercargill, crocus: plant by 9 May. The winter here is too mild for our late-planting rule, so we give no later limit.

Crocus in Invercargill: soil, season and weather

No month averages below 0 °C at night; the coldest nights, in July, average 5 °C.

Planting	by 9 May
First autumn frost	8 June
Coldest nights	July, 5 °C
Soil back at 1 °C in spring	already in the first week of July
Daylight	9:38 on 9 May
Daylight at the winter solstice	8:35

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

Crocus in Invercargill: 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 Invercargill 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 Invercargill, Queenstown is 19 days earlier and Nelson 13 days later.

City	Distance	Date	Difference
Queenstown	154 km	20 April – end of June	19 days earlier
Dunedin	176 km	22 April – end of June	17 days earlier
Timaru	318 km	by 5 May	4 days earlier
Christchurch	464 km	by 6 May	3 days earlier
Nelson	694 km	by 22 May	13 days later
Blenheim	705 km	by 1 May	8 days earlier

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