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Oxalis tuberosa - Molina.

Common Name Oca
Family Oxalidaceae
USDA hardiness 6-9
Known Hazards The leaves contain oxalic acid, which gives them their sharp flavour. Perfectly all right in small quantities, the leaves should not be eaten in large amounts since oxalic acid can bind up the body's supply of calcium leading to nutritional deficiency. The quantity of oxalic acid will be reduced if the leaves are cooked. People with a tendency to rheumatism, arthritis, gout, kidney stones or hyperacidity should take especial caution if including this plant in their diet since it can aggravate their condition[238].
Habitats Unknown in a truly wild situation, though plants have been found growing at heights up to 4000 metres in the Andes[97].
Range S. America - Colombia, Peru.
Edibility Rating    (5 of 5)
Other Uses    (0 of 5)
Weed Potential No
Medicinal Rating    (0 of 5)
Care (info)
Fully Hardy Moist Soil Full sun
Oxalis tuberosa Oca

Oxalis tuberosa Oca


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Physical Characteristics

 icon of manicon of flower
Oxalis tuberosa is a PERENNIAL growing to 0.5 m (1ft 8in) by 0.3 m (1ft).
See above for USDA hardiness. It is hardy to UK zone 7 and is not frost tender. It is in flower from July to August. The species is hermaphrodite (has both male and female organs) and is pollinated by Insects.
Suitable for: light (sandy) and medium (loamy) soils and prefers well-drained soil. Suitable pH: mildly acid, neutral and basic (mildly alkaline) soils. It cannot grow in the shade. It prefers moist soil.

UK Hardiness Map US Hardiness Map


O. crenata.

Plant Habitats

 Cultivated Beds;

Edible Uses

Edible Parts: Flowers  Leaves  Root
Edible Uses:

Tubers - raw or cooked[2, 103, 183]. An acid lemon flavour when first harvested, if left out in the sun the tubers turn sweet[183], so sweet in some varieties that they are said to resemble dried figs and are sold as fruits in local markets in S. America[34, 37, 97, 196]. The cooked root is delicious whether in its sweet or acid state, it can be boiled, baked etc in similar ways to potatoes[K]. The tubers tend to be rather smaller than potatoes, with good sized specimens reaching 8cm or more in length. The slightly waxy skin makes cleaning them very easy[K]. They contain about 70 - 80% moisture, 11 - 22% carbohydrate, 1% fat, 1% fibre and 1% ash[196]. The carbohydrate is rich in sugar and easy to digest[196]. Acid types are rich in oxalic acid (up to 500ppm) but sweet forms have much less oxalic acid than is found in potatoes[196]. Edible young leaves and flowers - raw or cooked[34, 37, 103]. Poor quality[33]. Use in moderation, see notes at top of sheet,

References   More on Edible Uses

Medicinal Uses

Plants For A Future can not take any responsibility for any adverse effects from the use of plants. Always seek advice from a professional before using a plant medicinally.

None known

References   More on Medicinal Uses

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Other Uses

None known

Special Uses

Food Forest

References   More on Other Uses

Cultivation details

Prefers a light rich soil in a warm sunny position[1, 37, 196]. Tolerates a pH range from 5.3 to 7.8[196]. Plants succeed in areas with an average rainfall ranging from 570 - 2150mm per year[196]. Oka is widely cultivated in the Andes for its edible tubers, there are many named varieties[33, 97]. This species has an excellent potential as a major root crop in temperate zones, it has the potential to yield as highly as potatoes but does not have the susceptibility to pests and diseases that are a bugbane for potato growers[K]. Plants are slightly more hardy than the potato, tolerating light frosts but the top-growth being severely damaged or killed by temperatures much below freezing. The main drawback is that development of the tubers is initiated by the number of hours of daylight in a day. In Britain this means that tubers do not begin to form until after the 21st of September and, if there are early frosts in the autumn, yields will be low[37]. There are possibly some forms in southern Chile that are not sensitive to daylength, these will be more suitable to higher latitudes such as Britain[196]. It is said that the varieties with white tubers are bitter because they contain calcium oxylate crystals whilst those with tubers that are of other colours are sweet[97]. However, we are growing one variety with white tubers and it most certainly is not bitter[K]. Yields tend to average about 7 - 10 tonnes per hectare but experimentally yields of 40 tonnes per hectare have been achieved[196]. Earthing up the growing stems as they start to form tubers can increase yields significantly[196].

References   Carbon Farming Information and Carbon Sequestration Information

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Plant Propagation

Seed - best sown as soon as it is ripe in a cold frame. Prick out the seedlings into individual pots when they are large enough to handle and plant them out in late spring or early summer. Seed is not usually produced in Britain. Harvest the tubers in late autumn after the frosts have killed off top growth. Store in a cool dry frost free place and plant out in April. Basal cuttings in spring[196]. Harvest the shoots with plenty of underground stem when they are about 8 - 10cm above the ground. Pot them up into individual pots and keep them in light shade in a cold frame or greenhouse until they are rooting well. Plant them out in the summer.

Other Names

If available other names are mentioned here

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Found In

Countries where the plant has been found are listed here if the information is available

Weed Potential

Right plant wrong place. We are currently updating this section. Please note that a plant may be invasive in one area but may not in your area so it’s worth checking.

Conservation Status

IUCN Red List of Threatened Plants Status :

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Growth: S = slow M = medium F = fast. Soil: L = light (sandy) M = medium H = heavy (clay). pH: A = acid N = neutral B = basic (alkaline). Shade: F = full shade S = semi-shade N = no shade. Moisture: D = dry M = Moist We = wet Wa = water.


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Botanical References


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Readers comment

John Ernest Berry III   Fri, 04 Dec 1998 21:59:20

I was delighted to receive your most recent issue about Oca. Are you allowing it sufficient time to attain it's potential size? After growing it for three years, I find they certainly take the majority of the "normal" growing period, & then some, to fully achiev their true size!!!

I relish the certainly far from insipid flavour that it certainly does manifest. Most of the people who've been adventurous enough to sample these malformed tubers are rather taken aback by the acrid taste.

I love the "spud with an internal dolop of sour cream".

A.Wigmore   Sun Jan 27 20:16:18 2002

I grow various unusual tubers in my raised vegetable beds: oxalis tuberosa, tropaeolum tuberosum , apios americana, dioscorea batatas (that one does not do well, probably too cold without protection), yacon. I wonder if any or all of them will benefit from a load of compost, and whether it is good to grow them in the same place year after year?

Susan Schofield   Fri Nov 5 10:55:01 2004

At last I have found information on the New Zealand yam (oxalis tuberosa). After living in New Zealand for 30 years I became very fond of the "yam" but could not find a grower over here. We served these roasted with potatoes but I also cooked them in a little butter with honey. Does anyone know where I can buy them over here?

Abayomi   Thu Sep 14 2006

Does anyone know where I can buy seeds?

   Wed Nov 22 2006

Keep very well, and easy to grow. The best way to cook them is roasting, but they can be eaten raw, boiled, in stir fry, etc. Very versatilve and easy to grow vegetable.

   Mon Feb 5 2007

Incredibly productive plant in coastal British Columbia (zone 7-8); harvest in early February has yielded several dozen 6-8cm long tubers from a single plant (1 gallon size). And what an excellent food: flavour has a citrus sweetness, a much more intense and satisfying flavour than Jerusalem Artichoke.

Denise Dellow   Sun May 27 2007

Nz'er living in UK. Desperately seeking some tubers for my vegetable garden, and pleased to discover that it is not an entirely unknown vegetable here. Can you advise whether it is freely available to gardeners and where I can obtain some stock? For those still learning to eat them, try steamed with a dollop of honey and grated fresh ginger.

Gina Z   Wed Sep 5 2007

Does anyone have any see or roots stock for sale , would love to try growing in Hawaii

Steve   Sun Sep 16 2007

Oca tubers can be purchased from www.realseeds.co.uk

Christophe Mouze   Fri Dec 7 2007

We have been growing them for 4 years now in the west of Ireland with very good results. This year, we got 30 Kg of them on a 8 sqm bed, that's 37 tons / hectare. The secret of good yields is to leave them in the ground as late as possible (we only harvested them in December this year). They are delicious roasted. We can sell some seeds, contact [email protected]

christophemouze   Sun Jan 20 2008

Growing and eating ocas

Marlene Ansley   Tue Aug 19 2008

My family lived in Georgia, USA and my mother used them as decorative flowers to border her flower gardens and shrubs. Had absolutely no idea they could be eaten. The leaves look like shamrocks and the little flowers are pink or sometimes white. WOW! I don't think my mother knew they were edible, I'm not sure where she got them from, she had a friend that was originally from Ireland, maybe she sent my mother some tubers and my mother planted them and enjoyed their flowers and leaves as a border. You learn something new everyday! [email protected]

paul johnstone   Thu Oct 23 2008

try the real seed company in the u.k. who sell the tubers but have limited stock so try soon .

Colleen Atkinson   Wed Nov 26 2008

Marlene, The ones in your mothers garden are probably only the decorative type. Tuberosa is the yam producing plant and not the same as the floral variey which produces a clear tuber which i would not eat.

Stuart Jeremy Oxley   Fri Jan 16 2009

Real Seeds Unusual Veg inc Oca, Yacon & Ulluco. Lots of veg seeds too. A++

Owen Smith   Tue Jan 27 2009

I've managed to get some home grown Oca seed to germinate. For details see my blog

Radix Blog about my experiences of growing alternative root crops

CarpeDiem   Wed Feb 11 2009

Hello, everytime, I'm looking for different colors from andean plants. Oca, Ulluco and Mashua are some of my favorites. Sometimes it is very difficult to get them.


NIGEL MURISON   Mon Mar 9 2009

I have oca tubers for sale.Postage to U.K. ONLY email [email protected]

jono   Fri Jun 26 2009

I have been growing Oca in Sydney Australia for four years. Summer is too hot so this year I am growing over the autumn/winter period. As we live in the inner city I am growing in pots and experimenting with bark to mound around the plants. I have found a mix of compost (30%) and sand (70%) to be the most successful as a base. For cooking my favourite is rolled in olive oil, sprinkled with chilli and roasted.

Ian Pearson   Wed Dec 2 2009

I have a blog recording my experience with bi-croping / companion planting Oca in the UK

Growing Oca

Lucy Hayward   Tue Jan 12 2010

Does anyone know where I can buy some Oca tubers to grow? Realseeds don't have any this year. Please could you let me know - many thanks Lucy. [email protected]

CarpeDiem   Thu Jan 14 2010

Since last year I have a platform for andean tubers. On this platform I list people who change andean tubers and I also colect informations and shops in differnt countrys and list them. Now it is a little project, but the platform and infromation growsare growing.

http://www.carpediem-living.de Platform for andean plants

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Subject : Oxalis tuberosa  
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