Oca (Oxalis tuberosa) – the other potato

Apparently there’s an Andean root vegetable called a potato and they are very popular over here in the UK. There are however some other unusual tubers that are becoming more popular. One of these is called the Oca (Oxalis tuberosa) or as I like to call them ‘the other potato’ but they are more usually referred to as one of the lost crops of the Incas.

Oca’s are from the Andes and have been harvested for hundreds of years and is more popularly known as the New Zealand yam where it is available in supermarkets. One of the things that is surprising is when you see Oca tubers pictured together how colourful they in fact are.

THE CLOVER TYPE LEAVES OF THE OCA CAN BE EATEN RAW AND USED IN SALADS, IT HAS A LEMON TASTE.

Oca yeilds

Dig them up and they should store well with a constant temperature ready to be eaten or replanted again next year. Reports tend to suggest yields are around half to three quarters of a kilo per plant or about 20 to 50 new tubers.

Although the leaves are edible they do contain oxalic acid which in large quantities can lead to calcium deficiency.

How Oxalis tuberosa tubers grow

They grow pretty much the same way potatoes do except the tubers swell when the days are shorter and usually in the UK a few weeks after the first frost. Possibly the reason it isn’t as popular as you’d expect is that it can be tricky knowing when to lift them. Lifting too soon and they will be too small, lifting too late and penetrating ground frosts can ruin the crop.

As they have such a relatively long growing season it is best to pot them up individually and grow in warm frost free conditions. They don’t like frost so only plant out when all chance of frost has passed. Frost damage to the leaves will set them back and they may not bulk up that year.

Alternatively you can wait till the danger of frost has passed and plant them about 2 to 4 centimetres into the ground. Spacing between the plants can be anywhere from 15cm to 90cm although the greater spacing will give them more room to grow and produce larger sized individual tubers.

The leaves themselves look like large clover leaves and can be eaten raw as part of a salad and have a tangy taste. You can pick them throughout the summer. They are actually part of the Wood sorrel family and not actually relate to the potato; another benefit of this is that they do not suffer from blight.

YELLOW FLOWERS OVER EDIBLE GREEN LEAVES.

In early autumn you will see the yellow flowers appear. By about mid September the tubers should start to swell. Some people who grow them suggest leaving them in the ground for a few weeks after the first frost as this increases yield. If they are left in the ground too long the frost will kill them or the slugs will eat them.

Oca yeilds

The texture is akin to new potatoes and Jersey royals are often mentioned as a favourable comparison. The difference is that they have a slight tangy lemony taste that is quite pleasant. You can leave newly lifted tubers in the sun for a few days to sweeten them although I have not tried this, yes they can be exposed to light and will not turn green like potatoes.

Unlike the humble potato you can eat them raw or cook them in the same ways you would a new potato. They have more of a nutty taste when cooked and you do not have to peel them either.