Oca growing and the dangers of bicycle transportation

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

Of course, in being so violently thrown all over the place, some of the oca also got separated from their sprouts. In a half-hearted attempt to make up for my foolishness I potted up these sprouts as soon as I came home and to my pleasant surprise almost all of them have since rooted. Some of these sprouts were really only half a centimeter or so tall, so these truly seem to be very resilient plants. Thus far this seems to be my kind of vegetable!

The sprouts that broke off easily rooted

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!

An old woman can't eat two

A brief update on the sweet potatoes. I've got plenty of slips [basically tuber sprouts that one pulls off and then replants] ready to be planted out, but the potatoes and me are all waiting for the weather to turn a bit more friendly. It's been 12 degrees here, rainy and windy - very much the complete opposite of sweet potato weather - and the slips I condemned to my balcony for 'hardening off' are just sitting there with wilted leafs looking miserable. Nevertheless I'm gonna have a go at it pretty soon, I will have more slips than I will be able to use anyway so planting some out a bit early seems like a good way to test their adaptive capacities..

Sprouting in progress

Meanwhile I've made a list of the varieties that I have and that seem viable. Probably the number will change (hopefully in the upward direction) but so far it's 26 different varieties. Most of the names that I got are in different local African languages, and it's really quite a pity that I don't know the translation for all of them, seeing how original some of these names are. My favourite must be 'mukekuru tarya bibiri', literally meaning 'an old woman can't eat two', a name holding out the promise of fast-maturing tubers with corpulent qualities. Another good one is 'Orphan', denoting its alleged ability to feed large families. Here's the full list (with reservations for the spelling on some of these...):

Nordic Purple - offspring from my own garden, unknown original variety, purple skin and purple flesh, produced respectable tubers last year.
Nordic Orange - offspring from my own garden, unknown original variety, red skin and cream-coloured flesh. This one also produced some respectable tubers but got pretty devestated by the voles.
Nordic White - offspring from my own garden, sourced this in the US, maybe O'Henry? This one actually didn't do very well, either the voles got all the big tubers or I only managed to get a few small ones.
T65 - only variety that produced a respectable tuber without ground mulch last year, probably one of the most promising for my climate. Red skin, pale cream-coloured flesh.
Georgia Jet - I didn't get any tubers from this last year, but I have two cuttings that seem to be hanging in there so hopefully I can give them a another try.
Orphan - white skinned, allegedly named like this because it's a prolific cropper that will feed large families
Kitekyere - white skinned, long and thin tubers
Sula - red skinned
Bamuhachira - red-purple skin, with very dark purple sprouts
NASPOT I - improved African variety, light brownish skin and very white flesh that is extremely dry. This reminded me more of cassava than sweet potato when I tried it. Supposedly a good variety for processing.
Orange-fleshed I - 
Orange-fleshed II - light brownish skin
Bunduguza - white skinned variety
Tangara - copper skin
Kwezi-Kume - light purple skin
Kipapari - light brownish skin
Kitemere - white skin
Kalebe - copper skin
Mushemeza - Highland variety, grows at or above 2000m
Rwababurugi - Highland variety, grows at or above 2000m
Mukekuru Tarya Bibiri - 'an old woman can't eat two', according to the person I received this from this one should mature in 1 month, which is hard to believe but we'll see! Also a highland variety.
'Asian Yam' - I got this from a US supermarket, no idea what it is..
Alira
Kanya
Kitambe
Mpama-Hegia

Different leaf colours and shapes on 4 sweet potato varieties

In contrast to the varieties available in the US/Europe, most African sweet potatoes have white to pale yellow flesh and a very high dry matter content. Current sweet potato breeding efforts in many African countries concentrate on producing orange-fleshed varieties because these have much higher beta-carotene levels (a dietary precursor for vitamin A) than native white/yellow-fleshed varieties. American orange-fleshed varieties are regarded poorly by African farmers because people tend to prefer potatoes with a higher starch content, and from what I've read there seems to be some kind of trade-off between beta-carotene content and dry matter composition. I will be growing some traditional US orange sweet potatoes and some of the improved orange African ones, but most of the varieties here are the traditional ones with white and yellow flesh and all kinds of different skin colours.

Meet the last of my organic aphid control crew