New Zealand Yam

I had a hard time locating this plant locally – and this scarcity pretty much guaranteed that I’d go to unreasonable lengths to find it. I never did find anyone who was willing to send me tubers in Canada, so my solution was to buy seed. After much internet searching, I found a very cool web site for a vegetable breeder in Washington State who grows some quite uncommon veggies. The site, in case you’re interested, is Cultivariable.

So why would I go out of my way to buy New Zealand Yam? Well, have a look at the tubers:

Oxalis in my handI couldn’t very well pass up the chance to grow something this unique. But let’s get some other interesting facts out there:

  1. New Zealand Yam is not from New Zealand. It’s from South America. My initial snooping on the internet tells me that it was bred by the same fine folks who brought us the potato. In South America, it’s called Oca.
  2. New Zealand Yam is also not a yam. It’s not closely related to either the true yam (Dioscorea) or the Sweet Potatoa (Ipomoea). It’s actually in the Wood Sorrel family, and is in the same genus as an annoying little weed, Oxalis corniculata.
  3. The tubers are edible. Raw, they taste starchy, like an uncooked potato, but also a little “lemony”. This acidic tang comes from the oxalic acid in the tuber. I find the flavor quite pleasant and fresh tasting, but for those who don’t like the tang, cooking neutralizes the acidity – and the tubers taste much like potatoes.

This was my first go at growing New Zealand Yam, and I was pretty happy with the results. Here’s what I harvested:

Oxalis harvestIt wasn’t enough to bring to the farmer’s market as a food crop, but it does give me a fair amount to play with for next year’s plantings. I’ll probably have some left over to bring to market as starts for other people who want to try growing something unusual.

Some notes on growing, just in case you’re inclined that way:

Oca begins forming tubers when the days get shorter than 12 hours. For us in the Fraser Valley, that means we have from late September until first frost – end of October if we’re lucky. Not a lot of time for tuber formation! There are two solutions I can think of for this, and next year, I’ll probably try both. One is to fool the plants by shading them in August – giving them a 12-14 hour “night” to force early tuber formation. The other solution is to grow them in a cold frame or with some other protection to extend the season past the first frost.

I spaced my plants at around 10 inches apart, and I didn’t think that “mounding” was necessary, so I just let the plants do their thing. Next year, I think I’ll give them a little more space (say 18″ apart). I also noticed that most of the tuber formation happened at the points where the side stems touched the ground. I’m thinking I might be able to encourage a better yield by adding some loose soil around these trailing stems.