Monday, December 6, 2010

Growing Oca (Oxalis tuberosa)

Hi everyone,
      This is my first post on my blog where I will try my best to document my attempts to grow plants that I think have a lot of potential here in the Chehalis Valley where I live, and also in other agricultural areas. My hope is to share my experiences with others growing these crops as well as inspire people to grow them.

The first plant I'm going to talk about is Oca (Oxalis tuberosa). There's a good deal of information about oca on the internet, so I won't give too detailed of a background on it here.

The plant is from the Andean highlands of South America where it has been grown for thousands of years and is still grown for its starchy tubers. They taste similar to potatoes, but with a nice lemony sour flavor. That's caused by oxalic acid in the tubers, which is found in spinach and sorrel is responsible for their sour flavor as well.

Tubers are planted around May, when the danger of hard frost has passed. They can be started earlier indoors, and transplanted, which gives them a bit of a head start.

Like potatoes, hilling them with soil increases tuber production. Tubers are formed only after the autumn equinox (usually Sep 21st.) and are dependent on the amount of daylight reaching the plants (Some exciting work is being done to produce oca that is daylight-neutral over at Radix Root Crops).

If you have early frosts, oca can be killed back before it produces a good amount of tubers. Therefore, if you live in a really cold area with early frosts, oca might not be a good crop to grow. In the United States, oca grows really well in coastal California, where it can be a perennial, and it can grow well in the Pacific Northwest too. I'm not certain how well they would do east of the Rockies, but you could certainly give them a try.

Harvesting should be done before hard frosts come. Foliage can die back and the tubers can be fine, but if temperatures get very cold (as in the teens and single digits), the tubers can freeze in the ground - something I've witnessed myself.

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I first grew oca in 2008 after I ordered some tubers from Nichols Garden Nursery in Oregon. I had heard about it on the PFAF website, and was really enthusiastic about growing them. I started them indoors in March, I believe (I didn't take notes, unfortunately, but have since learned the importance of taking detailed notes). It did well, and survived our record-breaking heatwave. I had read that oca did not do well in extreme heat, but it successfully survived 107ºF (41.6º C). I harvested them that fall, and ended up with a fairly good crop. Here's photos of the plants in fall shortly before I harvested them. Apologies for the poor quality. Note the plants are a little frost-damaged already - the plants in the top photo look somewhat brown and slimy in spots.

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