I like growing weird things. Things you don’t see in the grocer, or only very rarely. Why? Because when things are in season in the garden, they are at their cheapest in the shops, generally speaking. So to make the most of a garden plot, it’s best to use it to produce things you can’t buy. And also because some of them look really cool, and you can slip them into “ornamental” gardens too.
These potato-like vegies are Oca, also known as New Zealand Yams (Oxalis tuberosa). They are related to the weed Soursob (Oxalis pes-caprae), which is obvious from the familiar three foiled leaves, and their similar tuberous structure underground. The underground perennating organ is what makes the weedy species in this genera so problematic in gardens: pulling them out usually leaves behind parts which can re-grow.
Despite having been served Soursob in a very expensive restaurant, I am not convinced of it’s food value. Oca, on the other hand is a staple part of the diet in parts of New Zealand, and throughout Polynesia in the South Pacific. Despite the common name, and the prevalence in cultivation there, the plant is not native to New Zealand. Like a huge proportion of garden vegetables, this one is from the Americas, where wild relatives can be found growing in the Andes, and cultivated varieties are also widely grown.
They are easy to grow, probably easier than Potatoes, and will apparently grow in partial shade. Planted in spring, they require a shortening day length, and a frost free environment to set good sized tubers. They don’t seem to have many pests, and the bushy plants are sort of attractive, though could be mistaken for a weedy cousin by an untrained eye. Unlike Spuds, which must be kept out of the sun to prevent them producing toxic alkaloids, Oca tubers must be exposed to the sun after harvest in winter to make them edible. The light destroys oxalic acid in the skin, and greatly improves their flavour. They can be eaten raw, which is how they are favoured in Mexico, or cooked. You could substitute them for Potatoes in just about anything. I am off to put these little fellas in pots, and see how they go.