Sunday, 22 November 2015

Oh! You pretty things

Winter has arrived also for the Andean crops in my garden, so it's high time for some updates. 2015 was my first year growing oca (oxalis tuberosa), a major root crop in many Andean countries and probably one of the better-known unusual tubers from that region. In total I planted 14 known varieties and 7 varieties that I tested for the Guild of Oca Breeders (GOB). Due to a bit of self-induced force majeure however, the former got thoroughly mixed up, so from now on they're all going through life completely anonymous (at least in my garden). I'm not one to judge a tuber by its name, and at a very practical level it really doesn't matter.

The oca patch in the middle of October
Ideally, the oca growing manual clarifies, one keeps her/his plants alive until the beginning of December if one is to benefit from a fully matured crop. This is because oca plants get slightly confused in the long-daylight hours outside of their native Andean range and respond by refusing to produce tubers until after the autumn equinox. Here on the west coast of Skåne, which you could think of as the California of Sweden, we usually have the first frost sometime in November, or even, as in 2014, the beginning of December, which is pretty good in oca-growing terms. Not so this year though, when a forecasted 4°C one night at the end of October turned into an ominous -0.6°C and caught me completely off guard, therefore pretty much decimating the oca patch. Highly unfortunate considering the 3 weeks of mild and frost-free autumn weather that followed... The GOB plants got completely killed, while the other plants got frosted about 3/4 of the way, probably because they were spaced closer together and had much more foliage. Again according to prevailing oca-growing dictates, one is supposed to leave the tubers in the ground for some two weeks after the plants are killed by frost, since the tubers continue to bulk up quite a bit during this time. Which I duly did, albeit impatiently so.

White variety, 540g
I can testify that, because of its colorful nature, oca is a highly satisfying crop to harvest. I would say it's a bit like gathering easter eggs. Except of course that oca is so much more exciting than easter eggs! I mean, aren't they incredibly pretty? So euhm... yes, I dug everything up, bagged all the tubers per plant, washed them, weighed them, and then selected the ones I want to continue with next year. Considering the earlier-than-ideal harvest, I was pretty happy with the results (but then again, I have never grown these before so I have nothing to compare to and probably would have been happy with nearly anything). Most plants produced somewhere around 200-300g of small to medium-sized tubers, with the best one being a completely white variety that yielded 540g. According to the information over at Cultivariable, oca can yield up to 1kg per plant. Clearly, I'm pretty far away from that, but it's a pretty decent start nonetheless. I'm saving all but the poorest performing varieties for next year, since I want to ensure that I continue to have the diversity required to produce seed. Oca is namely a bit picky when it comes to pollinating partners.

Oh! You pretty things! These are the discards,
the tubers from plants that yielded less than 200g

GOB14178 - This from two plants
Speaking of seed, quite a few of my oca flowered, and some produced seed in late summer and early autumn. With some 25 seeds in total, this can hardly be called a gigantic harvest, but it's enough to do a little bit of excited experimenting next year. For the more substantial work of breeding that elusive daylength-neutral oca variety, I'll be relying on the likes of the GOB. Sadly though, this year's GOB varieties didn't do well at all in my garden. The only one that produced something worth mentioning was GOB14178. While the yield of seed-grown oca is bound to be very variable, the main reasons for the substantial difference between the GOB and non-GOB varieties in my garden are probably environmental. I planted the GOB varieties in a new plot of land, that I acquired just this year, and which turned out to have very low soil fertility and a pretty severe wireworm infestation. Basically, the GOB plants never looked happy and remained stunted throughout the season. In other words, I'm blaming mismanagement by the previous owner. Objective #1 for next year: Nurture the soil, and provide better conditions for GOB trials.

Other oca objectives for 2016: Regrow all but the worst of this year's varieties, keep them alive longer than this year, and produce more seed. Oh, and grow out this year's seeds. Ultimately, as I source more varieties, I also want to start selecting for taste and texture. So far I've only tasted a few varieties, but all have been very good, and some were outstanding. The texture seems to range from quite watery to potato-ish, and the taste from quite sour to starchy, to fairly sweet. Very interesting tastes, actually. I think I would like to select for varieties with a higher dry matter, and for less oxalic acid (i.e. a more neutral or slightly sweet tasting).

Oca's here to stay!