by Kriss Erickson

Created on: June 03, 2008

Growing Oca or New Zealand Yam

I'm always eager to learn new things about gardening, especially about plants that are both decorative and useful as food or herbs. Each year I scour plant and seed catalogs to see what new items I can add to my garden. This year I discovered Oca, a plant that has lovely foliage like a shamrock but that also grows edible tubers beneath the ground.

VERSATILITY

Though Oca is commonly known as New Zealand Yam, the plant is Oca is native tot he highlands of South America. Oca is related to shamrocks, as both are oxalis plants from the wood sorrel family. Oca's botanical name is oxalis tuberosa for obvious reasons. The foliage is shaped like shamrocks and instead of the slightly thick roots found beneath ornamental shamrock plants, oca produces tubers that look like short versions of carrots. Oca is a bushy plant that makes it ideal for small gardens. Oca grows up to 14 inches tall and makes bushes about 1 - 2 feet in circumference. The oca bulbs I bought in March of this year (2008) have already produced several large, bushy plants. I am anticipating a nice crop of oca later this summer.

CULTIVATION

Oca is a hardy plant that tolerates cold climates well. Freezing temperatures will kill the leaves but as I discovered after an unseasonably late snowfall, the roots are unharmed and the leaves grow back as soon as the temperatures rise. Oca, like potatoes, should be planted in the spring when the weather is still cool. Oca will wilt if temperatures reach 80 degrees or higher, but by then the tubers should be ready to eat. Oca begins to produce tubers about 4 months after being planted, with mature tubers ready after about 6 months. I placed my oca starts in a large container filled with potting soil to give it an extra good start. As I watch this hardy plant thrive, though I realize that I could have planted it near my potato plants and it would have done just as well. Oca tubers don't need to be buried deeply-about an inch of soil will do it. Plant each oca tuber about 12 inches apart to give room for each tuber to produce a nice crop of tubers. Also like potatoes, oca plants like to be hilled after a couple months. Use extra dirt, grass clippings and or mulch to mound around the plants, as you would when growing potatoes.

HARVEST AND USES

Like potatoes, oca leaves will start to die back then the tubers are ready to use. Oca tubers don't store as long as potatoes, but if you set them in the sun to harden for a few days, they should keep for several months at room temperature, in a cool, dark, dry storage area. Oca tubers can be used like potatoes, hence the common name of New Zealand Yam. Try them baked, broiled, fried, boiled, mashed or as part or all of a potato salad. Since oca is a member of the wood sorrel family, its leaves can also be used like sorrel, in salads or steamed and eaten as a vegetable. The Green Harvest web site, based in Australia, says that in the Andes Mountain area, mature oca tubers are placed in the sun for a few days to sweeten them.

One of the nicest things about oca tubers is that once you buy them, you don't have to buy them again. Just choose the biggest, healthiest tubers to store for the following year. Place them in sawdust in a cool, dry, dark place until next spring. Or, leave a few in the ground as you would potatoes or Jerusalem artichoke, and those will return next spring.

BUYING OCA TUBERS

Oca tubers are available from One Green World for a little under $8.00. Visit onegreenworld.com and use the search function to look up 'oca' to order.

Oca has been an easy, rewarding plant to grow. I can't wait to decide on a new multipurpose plant to add to my garden next year.

Learn more about this author, Kriss Erickson.
Click here to send this author comments or questions.