New Zealand Yam - Oxalis tuberosum

New Zealand Yam - Oxalis tuberosum


$5 per 300 grams from the Tasmanian farm. These can be collected, message us to make arrangements.


This unique, unusual but delicious tuber is oca (Oxalis tuberosum), but is also known as New Zealand Yam.

Plant oca in frost-free areas any time from July to October; if frost is a problem then wait until September or October. Bury the tuber under 2–3cm of soil with about 20cm between plants. Dig some compost or well-rotted manure into the soil before planting, but don't overdo it, as too much fertiliser will give you lots of leaves and very few tubers. The leaves form a dense clump of typical oxalis foliage becoming more prolific through spring and summer. The stems may flop and spread, if you have room then put soil over the top of some to enourage more roots and so more tubers. Feed every couple of months, but ease off in autumn. Also, make sure they are well watered during hot and dry conditions.

The bulbs swell and form as we approach the shortest day, so the longer you can leave them in the better. Once the whole plant has died back, or frost has killed it, the tubers are ready to be harvested. When first harvested they have a lemony flavour that is caused by the presence of oxalic acid. If this is too strong for you or if you have problems with oxalic acid (it can aggravate arthritis and related ailments) then leave the tubers out in direct light for a few days to break down the oxalic acid. Storage is easy because, unlike potatoes, tubers do not turn green on exposure to light. Wash and store them in hessian or cotton sacks, or piled into pots or plastic trays out of direct light in a dry airy position.

Cook tubers like new potatoes, add them to soups or eat them raw and chopped, sliced or grated into salads and sandwiches. They can also be baked (esp with roast beef ofr lamb) or fried. Leaves are also eaten and have a delicious sharp lemony flavour. Add them to salads.


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