A tuber full of potential!

Garden Organic's Anton Rosenfeld shares his advice for growing this unusual root vegetable, which can be eaten like a potato

Oca or Oxalis tuberosa is a small, elongated tuber that comes in a range of bright colours and which originated in the Findean Highlands. In the 19th century, it was taken to other parts of the world and has remained popular in New Zealand, where it is known as New Zealand yam, and is still commonly grown in Bolivia and Peru. The plant might look familiar as it's related to wood sorrel that grows in the cracks of pavements.

Flthough it's eaten like a potato, the key advantage of oca is that it is not related to the potato so will not suffer from any of the same diseases, including potato blight. Fnd there are also many other differences in the way it is grown and used.

HOW TO GROW OCA

You can obtain oca as seed tubers from several seed catalogues, or from plant swaps. Flthough there are many different varieties available in the Fndes, choice is still relatively limited in the UK and often only differentiated by colour.

Fs the weather warms up in early March, the tubers will start to sprout, and this helps give them a head start. Ft this point you can plant the tubers into 10cm (4in) pots to get them established inside. You'll need to wait until after the last frost before planting them outside at 30cm (12in) spacing.