Oca and Chinese artichoke: Two interesting root vegetables

Oca (left) and Chinese artichoke (right)

A while ago I had written a blog post about the unusual fruit and vegetables I am growing on my allotment. Among these were two root vegetables, oca and Chinese artichoke. I am now in a position where I can report back on these vegetables and if they are worth growing as I had them on the allotment for a full growing season, have harvested and eaten them.




Chinese artichoke

Chinese artichoke (Stachys affinis) is part of the mint family (Lamiaceae) and related to our native Stachys sylvatica and S. palustris. The difference is that Chinese artichokes produce edible tubers along their roots. The plant itself is not very pretty; on my allotment it grew to around 60 cm and had nondescript dark green leaves and very small purple flowers. I would not plant it in a flower border but it would be right at home in a vegetable garden. The tubers can be planted any time from autumn to early spring directly where they are to grow. Once the soil warms up they grow away without any problems and don`t need much care over the summer apart from keeping the weeds down and the occasional watering in a dry spell. The plants died back in October, and in November I harvested the tubers. I had planted a short row, 5 tubers in total, about 20 cm apart, in February, and harvested about 45 decent-sized tubers in November. I left all the smaller tubers in the ground as they will grow into new plants in spring. For this reason it is best to give Chinese artichokes a permanent position as it is nearly impossible to get all the small tubers out of the ground. To remove these plants from the vegetable plot completely they need to be left to grow and dug out in summer before the tubers have formed.

Now the taste test. I washed the tubers thoroughly as they don`t need to be peeled. I then cooked them in lightly salted water for about 7 min until tender. I had them as a side dish with calabrese and mashed potatoes, but they would fit into many other dishes as well. I was pleasantly surprised as the tubers have a slightly creamy, buttery consistence and a really nice nutty flavour.

Chinese artichokes are a tasty treat

Conclusion: Chinese artichokes are easy to grow and don`t need much care. Harvesting is easy but the yield is low as the tubers are quite small and each plant does not produce great amounts of them. The taste is great, nutty and delicious. This vegetable needs to be used as a special treat, not a stable food such as potatoes, due to the low yield. I am already looking forward to my next harvest in a year`s time.

Oca

Oca (Oxalis tuberosa) is part of the oxalis family (Oxalidaceae) and related to our native wood sorrel (Oxalis acetosella). The plant has clover-like leaves and yellow flowers in early autumn. The tubers are only produced in autumn when the days are getting shorter and for that reason the plants need to  grow for as long as possible into autumn and early winter to produce the highest yield.
I planted the tubers singly into pots in April and left them in the greenhouse until I could see the first shoots growing. The plants are very frost tender so cannot be planted out before the middle of May at the earliest. You can also plant the tubers directly into the ground from mid-May onwards. The plants need quite a lot of space, I planted the tubers around 40 cm apart from each other. At first oca grows quite slowly but once it gets going in summer it grows into quite enormous plants which later in summer sprawl over the ground. Don`t underestimate the space oca will need. I also watered the plants in dry spells.

Young oca plants in June

Oca plants (behind the leeks) in July

From autumn onwards you need to watch for frost as oca will produce more tubers as longer it is in the ground in autumn and early winter. Even a light frost will damage the leaves but it helps to cover the plants with a thick fleece when frost is forecast.
I harvested my oca in the middle of November once the leaves had died down after a heavy frost. I found quite a lot of tubers, about 20-30 tubers per plant, which were growing close to the surface so were easy to harvest. Do not leave the tubers in the ground over winter as they will not survive a heavy ground frost. They are easy to store in a plastic bag in a cold but frost-free shed or in the fridge. The tubers will keep until spring when they can be brought back into growth to start the cycle again. So don`t eat all of the tubers :-).

Now the taste test. I washed the tubers thoroughly and, as with  the Chinese artichoke tubers, they don`t need to be peeled. I cooked them in slightly salted water for about 10 min until soft. The taste was very good, like a flavourful potato with a slight hint of lemon. Raw the tubers taste like a crunchy apple with a lemon flavour but I prefer them cooked.

Oca tastes like a flavourful potato

Conclusion: Oca is easy to grow and does not need much care apart from regular watering in dry spells. The plants seem to be quite free from diseases and had no slug or caterpillar damage at all. For a good yield they need to be protected from frost in autumn as long as possible, best until at least mid-November. The taste is excellent and the yield much better compared to Chinese artichokes. But in my opinion it is worth growing both as they do taste different.