One of the root crops I'm trialling this year is oca (Oxalis tuberosa), an Andean tuber popular with fellow tuber enthusiasts but largely unknown with the potato-consuming crowds of Europe and North America (curiously though, it does seem to have established itself as a minor crop in New Zealand). Oca is an important staple in the Andean highlands, primarily Peru, Ecuador and Bolivia, and seems to have everything going for it: it grows fairly easily in harsh environmental conditions and poor soils; produces yields (potentially) rivalling those of the potato (at least in the Andes); and according to reputable sources (i.e. wikipedia) is a high-quality dietary source of potassium, vitamin C and iron amongst others. It is supposed to have the taste and texture of a potato, but with a lemony aftertaste (because of the varying levels of oxalic acid the tubers contain), though taste, along with colour, size, and yields in oca appears to differ widely depending on the variety. I wouldn't know to be honest, because I've never tasted one, but with some luck that's all about to change this winter. May this be my annum tuberosum!
I sourced some 14 (if I remember correctly...) different varieties past autumn, one of which came directly from Peru, and chitted them in egg cartons on my windowsill for a few weeks, much like potatoes, though these sprouted much slower. The Peruvian variety had started growing already when I received it and it was looking pretty shriveled by January so I potted up the tubers and grew them out on the balcony when it wasn't freezing. This is what it looked like back in April, just before I planted it out in the garden:
|Oxalis tuberosa, var. 'annelotte'|
The reports I read suggested that a lot of people pot all their tubers before planting them out but I had neither the space nor the patience for this, so I decided to give all the others the potato treatment instead and plant them out directly after my last average frost date. I thus meticulously labelled my egg cartons with the names of the different varieties and then, one sunny day at the end of April, packed everything into my bicycle crate and set myself on my way to the allotment.
|The science of egg carton chitting... here, oca and ulluco|
I should have anticipated the result, for, notwithstanding this place being the Valhalla of bicycling, the road to my allotment is anything but even and I have over the years upturned plenty a plant start with what appears to be my excessively enthusiastic bicycling style. Anyway, suffice it to say that by the time I arrived, the oca's had been happily bumping all over their egg cartons, making my labelling efforts completely redundant and therefore putting a premature end to my intentions to systematically keep track of, and compare, the progress of the different varieties I have in my possession. Instead of making neat little variety-specific groups in the oca bed, as I had planned, I thus had to resort to planting everything at random. Please forgive me, Carl von Linné, but I suppose that as long as they grow well, I don't care so much what all of these were originally called. And grow they do, at least for the time being! With some exceptions, most of the plants have emerged by now, and they seem to be escaping the voracious appetite of the slugs in my garden this year. I wished that could be said of my Brassica seedlings, which keep disappearing overnight...
|The oca bed, the four plants in front are the Peruvian variety|
that got a headstart on my balcony
What next? As most of the Andean root vegetables, oca is a daylight-sensitive plant and only starts producing tubers when days are short enough, sometime after the autumn equinox. In a frost-prone climate this essentially means that in order to get any kind of yield at all it's crucial to secure growth until well in November, which is far from impossible here in the Swedish south, but it's certainly not a given either. Oca enthusiasts such as Rhizowen and Bill Whitson are attempting to breed varieties that are daylight-neutral, and these are bound to pop up at some point (after all, the common potato started off as a daylight-sensitive plant as well), but until then, I suppose I'm facing the real possibility of an early frost killing all my plants before a single tuber has formed. At the other extreme, my plants might feel comfortable enough in their new surroundings to flower and produce seeds, which would allow me to do some oca breeding myself in the future. Fingers crossed!