Last edited on October 20, 2026. View history

Stewart Island Potato

No scientific name recorded

Also known as Rakiura potato (en)

A variety of potato

How to sow Stewart island potato: Direct seed outdoors after last frost. Each piece must have one eye.

Sun requirement for Stewart island potato: Plant in Full Sun

Found by Kay Baxter growing wild in a cliff face along the shore on Stewart Island. Rare, heritage, unknown whakapapa.

Preserved by Koanga Institute.

Very tasty and a big cropper.

Found by Kay Baxter growing wild in a cliff face along the shore on Stewart Island around 1990. It is an extremely beautiful variety similar in shape to Whataroa and Chatham Islands however this one has pink rather than purple colouring on the skin, and the eating qualities are different. It is more floury rather than waxy.

3: plantings
2: harvests
4: seed packets

Growstuff is a free, community-run site for people who grow food. Keep track of what you plant and harvest, find seeds to swap, and see what is growing near you. Join to record your own Stewart island potatoes.

Stewart island potato facts

Lifespan

Annual living and reproducing in a single year or less

34 weeks median lifespan

First harvest expected 51 weeks after planting

Grown for

tuber harvested 2 times

Optimal temperature 15–25 °C

Absolute temperature 7–30 °C

FAO EcoCrop

Optimal rainfall 500–800 mm/year

Absolute rainfall 250–2000 mm/year

FAO EcoCrop

Optimal soil pH 5–6.2

Absolute soil pH 4.2–8.5

FAO EcoCrop

Crop cycle

90–160 days

FAO EcoCrop

Max altitude

2800 m

FAO EcoCrop

Optimal light

very bright

FAO EcoCrop

What are growing degree days?

A plant grows with warmth, not with days. A growing degree day is one day's worth of useful warmth: how many degrees the day's average temperature is above the lowest temperature the crop grows at. Add them up from planting and you know how far along the crop is, whatever the calendar says.

Say that lowest temperature is 10°C. A day averaging 17°C gives 7 growing degree days. A day averaging 8°C gives none, as it is too cold for the crop to grow. That is why the same lettuce takes about 50 days in a summer and 90 in an autumn: it needs the same total warmth either way.

For Stewart island potato, the FAO EcoCrop database gives a lowest growing temperature of 7°C and a shortest growing cycle of 90 days at its best temperature, about 1170 growing degree days to a first harvest.

Where you've told us where your garden is, we use this and the weather there to predict when your Stewart island potato will be ready to harvest. We don't use it for how long a plant lives or when it finishes: we go by what members have logged for that.

Growing Stewart island potatoes

Sit seed potatoes in the light to sprout 4 weeks before planting out
Dig compost into the bed 1 week before planting out
Earth up the shoots 3 weeks after planting out every 2 weeks
Check the leaves for blight 5 weeks after planting out every 2 weeks
Water in dry weather 6 weeks after planting out every week
Dig the first new potatoes at first harvest
Lift the main crop 6 weeks after first harvest
Dry the potatoes and store them in the dark 7 weeks after first harvest

How members grow Stewart island potatoes

Sunniness

Planted from

Harvested for

Plant Stewart island potatoes with

eggplant

marjoram

Photos

Stewart island potato plantings

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