Oca, also known as New Zealand Yam, is a member of the Oxalis family. In order to grow it, it is best to start with some tubers. These come in a variety of colours; yellow, pink and red which make a pretty crop. Mine are much smaller than potatoes at about 1-3cm length, although I have seen larger varieties around.
At this time of year, the tubers will start to sprout and can be kept in a light place to avoid the sprouts getting too long and tangled. I plant mine out in early May, when they are unlikely to be affected by frost damage. They grow well in large containers or in a fertile vegetable bed. After a few weeks, you will see some sprouts and leaves start to emerge. Oca has quite pretty leaves; they are heart shaped, similar to wood sorrel. Like other members of the sorrel family, they have a sharp citrus flavour and can be added to salads. They should not be eaten in huge quantities however and some people are prone to gout and kidney stones if they consume them.
While the plant is growing, your little tuber will be turning from one into perhaps 30 tubers. These remain quite small until late in the year, so don’t be in a hurry to dig them up. Real Seeds advise that you wait until at least a week after the first frost kills the folliage. Last year this was at the end of November. As the folliage dies, the plant draws its nutrients into the tubers, so they grow rapidly at this time.
Once you harvest the tubers, wash them and keep them somewhere cool and dry. They keep well for many months. You can can fry, roast or boil oca like potatoes. They have a slightly waxy texture and a mild lemon flavour. Even my children who are generally adverse to any vegetables, let alone strange unknown ones, could not find much to object to about eating these. While I would not claim they are delicious, they taste fine and are a good crop to grow, with no pest or blight problems.
Don’t forget to save some of the tubers to replant the following year. Once you have bought some, you should never need to buy them again. Saving the biggest and best will hopefully lead to even bigger harvests. One website I have read says that you can also propogate new plants during the growing season by taking cuttings with a few leaves on, putting them in water until they form roots and then planting these out. I think I will try this out this year.
