Thompson & Morgan

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New Zealand Yam

Oxalis tuberosa, Oka, Oca

Tender Tuber

 Customer Rating

  • Introduced exclusively by T&M
Also known as the New Zealand Yam, this unusual member of the Oxalis family has long been grown in the Andes for its nutritionally rich tubers with a tangy lemon flavour that becomes nuttier once cooked. The red skinned tubers have a crisp pale orange or creamy coloured flesh that can be eaten raw in salads or boiled, baked, and fried - just like potatoes. You can even add the attractive shamrock-like leaves and shoots to salads for a refreshing citrus twist. Oca makes a particularly attractive crop in the vegetable garden or even in a container on the patio. Height: 30cm (12"). Spread: 60cm (24").

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How to grow Oca (New Zealand Yam)

Ideal For:
patio, kitchen garden, greenhouse
Flowering Period:
August, September
full sun
    • 5 New Zealand Yam tubers

    • Despatch: By end of March 2017
    • £8.99
    • 10 New Zealand Yam tubers

    • Despatch: By end of March 2017
    • £12.99
Pot up Oca tubers individually into 15cm (6") pots of good quality compost and grow them on in warm, frost free conditions. When all risk of frost has passed, plant Oca out in any well drained soil in full sun. For optimum tuber production grow Oca at a distance of 90cm (36") apart, and cover with fleece until fully established.

Water Oca regularly, particularly during dry periods and especially from mid September when tubers begin to develop. An occasional feed with a general fertiliser and a mulch of well rotted compost will also help to encourage strong growth.

Oca requires long day lengths to grow and will not initiate tuber production until day lengths shorten in the autumn. Some tubers may form on the stems and these should be harvested before the first frosts. Do not harvest the underground tubers until the foliage has become frosted and died back in late November and December. Carefully lift tubers taking care not to bruise them. Oca tubers can be stored for several months in a cool frost free shed. Do not exclude light as this will help to sweeten the tubers.

Seeds and garden supplies will normally be delivered within the time period stated against each product as detailed above. Plants, bulbs, corms, tubers, shrubs, trees, potatoes etc are delivered at the appropriate time for planting and will be stated on the product page or in your order acknowledgement page and email.

Orders for packets of seed incur a P&P charge of £1.95.
Orders which include any other products will incur a P&P charge of £4.95.
Where an order includes both packets of seeds and other products a maximum P&P charge of £6.90 will apply - regardless of the number of items ordered.

Please see our Delivery / P&P page for further details and details of any surcharges that may apply to certain destinations.

  1. Let down

    By Wendy Gregory 05-04-2016

    I ordered these as I had grown and eaten them when living in New Zealand and wanted to grow some here. The pack arrived with five of the tiniest tubers I've ever seen, they were badly dehydrated, and the flesh was damaged. Not good quality produce for growing from at all, and very different in looks from those displayed in your photograph. To say that I am disappointed is an understatement. I have come to expect better from T&M, these simply won't do the job they need to do.


    Thank you for your review. I am sorry to learn of your disappointment with your purchase. If you would like to contact our Customer Care Department at, one of our agents will be more than happy to look in to this further for you.

  2. great alternative to potatoes

    By Joelle Nicholson 10-08-2014

    I first came across these in NZ and loved them. They make a great alternative to potatoe wedges. I had to wait 10 years for them to appear in this country and was delighted to find them at T&M. I have had years of blight up in Scotland so wanted an alternative to potatoes and this year have replaced half of them with this crop in my allotment.


    Thank you for your review. I hope we can continue to be of service.

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