Mauka meets Sweden, take one

I was not actually being very correct last time when I wrote that my tuberous adventures in 2014 were entirely restricted to sweet potato cultivation. There is one other rather exotic crop that I got my hands on this year. In fact, this is probably one of the most exotic tubers out there, eclipsing the humble sweet potato by lunar magnitudes. I am speaking, of course, of mirabilis expansa aka mauka, miso or chago, an Andean root vegetable that is as deliciousy mysterious as its multiple names suggest.

Mirabilis expansa

Since my ambitions in growing Andean root vegetables far outweigh my patience in actually acquiring the plant material, I have recently gone ahead and purchased Lost Crops of the Incas, the 1989 standard work for aspiring cultivators of unusual and long-forgotten plants from the Andes. The book contains some intriguing facts about mauka. Believed to have been a staple crop of the Incas, mauka was completely unknown to scientists (a fate that many an animal and plant species would probably benefit from) until the beginning of the 1960s, when it was found being cultivated in remote parts of Ecuador, Bolivia and Peru. Growing at altitudes above 2700 meters, it is said to be particularly tolerant of harsh conditions, which of course makes it a promising plant to try in more Northern latitudes. Its alleged ability to grow to mythical proportions over the course of one or sometimes multiple seasons (it appears to be a perennial though its frost tolerance is uncertain) has inspired some people to describe it as some kind of Andean cassava. Frank Van Keirsbilck told me they tend to weigh 800g to 2kg after one growing season in his garden. As most tuber crops, mauka is believed to be very nutritious, and, more importantly perhaps, is also reported to be delicious. Descriptions on the internet place the taste somewhere in between potato, parsnip, and sweet potato. Now, these just happen to be three of my favourite foods in the world, so there was plenty of reason here to make me very excited indeed.

Harvesting mauka

I was then quite pleased last spring when I managed to acquire two cuttings of the CIP208001 variety (courtesy of Rhizowen, and actually also of Frank, who is the original source of the plant in Europe and who also sent me cuttings, though these didn’t survive the onslaught of the Belgian/Swedish postal system). Since this was probably one of the first times that mauka graced these parts of the world with its presence, I first pampered the cuttings on my balcony until they seemed strong enough to stand their own in the real world. For space reasons (read: I’m horrible at planning) they ended up in the border of my garden, where they soon took off and seemed happy enough. Nothing really seemed to disturb them very much, not even the vole invasion in the nextdoor sweet potato patch or the biblical floods in early autumn that temporarily turned my garden into an miserable wetland. Though apparently not daylight-sensitive like many other Andean crops, Mauka roots seem to bulk up fairly slowly, and it was therefore good fortune that the first frost came fairly late this year, just a few days ago in fact. The frost was very mild and killed just the top leaves, leaving much of the foliage undamaged, so I could probably have left the plants in the ground for a while longer. Impatient gardener that I however am, I didn’t want to wait any longer so I harvested the rest of the leaves for salads and ommelette-fillings (and pretty tasty they were too!) and dug up the roots. Amazingly, I already found some new growth sprouting from the top of the roots, so this certainly is a plant that wants to grow.
    

The two underwhelming tubers... on a piece of A4...

I hope this does not turn into a trend on this blog, but the harvest, dear reader, was not exactly something to write home about. The two tubers weighed about 150g each. My plan was to eat one, and save the best one to resprout next year, but at 150g that seemed somewhat premature to say the least. I’ve therefore postponed the taste test to next year and stored both of the roots on my unheated attic (for lack of a better option), where I hope it will be cold enough to keep them from sprouting too soon. I’ve previously also taken a dozen or so cuttings that are happily growing new leaves at the moment, and I have received at least one new variety (mauka blanca) to try next year. Together this should give me plenty of plant material to carry out a proper trial next year, in the absolute best spot my garden has to offer. It’s all uphill from here for mirabilis expansa!

The 2015 mauka babies

A whole lot of could’ve been…

Yesterday was the day that I could no longer contain my impatience and finally dug up my sweet potato plants. The temperature had already gotten dangerously close to freezing one night in September, and since tuber growth apparently slows down significantly below 15 degrees, I figured there was no point in delaying further. The two rows I planted (about 25 plants in total) had been in the ground for well over 4 months, which should be more than sufficient time for the roots to size up to positively monumental proportions. Indeed I would be lying if I said I was expecting anything else. As I made my way to the allotment for the first time in over a month, I was picturing the mountains of sweet potatoes that I would be excavating. Tubers the size of melons there would be!

Cleaned out pretty thoroughly...

The sorry state of some of the plants should have forewarned me of the gloomy scenes to follow. Instead, I imperviously checked on the rest of the garden, harvested some late winter squash and dug up some potatoes before directing my attention to the sweet potato patch. I shrugged off the dying foliage on the plants in the first row as end-of-season fatigue and carefully set myself to removing the plastic mulch and laying aside the vines. The first thing I found there was a vole, fat and recently deceased, presumably, I now surmise, from gluttony. Under the first plant were the leftovers of its last supper: a sorry bunch of eaten-out sweet potato skins, which, from the size of them, hinted at the once substantial tuber that must have been here. Undaunted, I quickly proceeded to the next plant, only to find the same scene repeated here. I felt a slight depression setting in as I continued to make my way through the patch. Plant after plant revealed the remnants of a feast made for kings. My awe for the voracious appetite of the resident rodent population was overshadowed only by my despondency at the sight of it all. As careful excavation made way for feverish, incredulous digging, my garden fork inadvertedly pierced some of the tubers that the beasts had neglected. O cruel, cruel world!

Not exactly a melon, but close enough!

All in all the voles devoured at least two thirds of the harvest. They seem to have taken a particular liking to the orange-fleshed varieties, of which not a single tuber survived the onslaught. I was able to rescue a few handful of the purple-fleshed and white-fleshed/purple-skinned varieties, some of which indeed sized up quite nicely. This and the size of the eaten-out skins suggests that it’s certainly possible to grow sweet potatoes in southern Sweden outside a greenhouse. While the plastic mulch undoubtebly played an important part in this, it probably didn’t do the vole activity any good, what with sheltering them from rain and predators and all. The row with the latecomers that I planted without plastic seems to have been spared. Here I found some small T65 tubers, at least enough to produce slips next year and give them a properly timed trial. I left some of these plants in the ground for now, perhaps they will bulk up a little more before it freezes.

This is the full extent of undamaged tubers. I also scavenged some half-eaten ones.

As winter draws near I will have plenty of time to brood on a battle plan for next year. It might be that I simply need to harvest earlier, since the tubers seem to have developed properly before the voles got to them. Or it might be that I have to abandon the mulching and leave the plants to fight the Scandinavian weather on their own. While this would make root development much more uncertain, it would certainly impose selective pressure for adaptation to Swedish summers on next year’s crop. I am somewhat ambiguous about taking this step, since I don’t mind some climatic cheating if it brings closer the possibility of some day harvesting those melon-sized tubers. After all, as much as I am eager to find those temperate-climate adapted varieties, I also have the more mundane question of my dinner to think of. To mulch or not to mulch, that is next season's question. Whatever it will be, I will likely have plenty of genetic diversity to work with. I managed to obtain an additional 23 African varieties of sweet potato over the past months, all of which I hope to trial next year, provided they make it through the winter. I might have the last laugh in this yet, voles!

23 genetically distinct opportunities for next year's attempt!

A sweet Swedish summer

Different varieties of sweet potato mingling

I have recently come to terms with my obsessive (if rather uninformed) pursuits in gardening, especially with respect to growing the more unusual, the not-so-adapted and the plain impossible here in the deep south of Sweden. Since I see no imminent end to this rather newfound passion of mine I figured I might as well make an attempt to systematize my efforts and along the way share some of my endeavors with anyone out there who might, just maybe, be interested. Hence the rationale for starting this ‘weblog’, I guess it’s as good as any.

While my ambitions for next year are great, the unusual, not-so-adapted and plain impossible this year mostly consists of a second-year attempt to grow sweet potatoes. I am tracking down and trying different cultivars in the hope of finding one or more that consistently produce reliably outside a greenhouse here and that happens to be delicious as well. Last year’s attempt produced a rather meager crop with the odd massive tuber here and there, but I had a late start and a lot of other excuses as well.  

This used to be two separate rows...

This year I’m growing 7 (or maybe more - I obviously have a lot to learn when it comes to botanical bookkeeping) different varieties. I have some Georgia Jet and T65, two early-maturing varieties kindly sent to me by Frank Van Keirsbilck. These are commonly grown in more temperate climates and should be able to produce quite well here. They got off to a bit of a late start this year though, so I’m not quite expecting a bumper harvest, but as long as I get enough tubers to produce my own slips next year I’ll be one happy man indeed. The rest is a bunch of unknown varieties that I collected from tubers in different shops here and there: 1 variety with purple skin/purple flesh, 1 purple skin/white flesh, 1 white flesh/white skin, and at least 2 different orange fleshed varieties. People who know me will readily affirm that I have an uncanny fascination for ipomoea batatas, so thinking about the day not so long from now when I will finally be able to lift all these beautiful specimens and see what they have been up to the whole summer makes me very excited indeed…

  

No seeds, but very pretty!

It has been pretty amazing sweet potato weather here this summer, with record-braking 30 degree temperatures, so I feel like I’m entitled to nothing short of an amazing harvest this year (uhum…). I planted most of the plants on a ridge covered with plastic mulch, and, in a somewhat ill-controlled experiment that included me forgetting to use the same varieties for both rows, then constructed a polytunnel over half of them and used a floating row cover over the other half, which I lifted fairly late in the season (end of July-ish), once the plants started to bulge out of the space they had been allocated. The polytunnel I left in place until late August, when I started to fear that the lack of space/increased rains would create rot on the vines. I also planted some latecomers, including the T65 and the Georgia Jet, in a separate patch without any mulch (I am, after all, looking for varieties that grow without too much pampering). If the foliage is anything to go by (and I know that it’s not), then the plants are doing great so far, with plenty of healthy growth. Two of the unknown varieties started to flower in the height of summer, and while I will probably have to store away my ambition of getting any seed for now, I have at least marked them as potential seed-producing contenders in some undefined future. All of the plants that flowered are in the space that had the row cover, so now I’m wondering if that might at all have played any role in inducing flowering. If anyone has any more informed theories about this, I’m all ears.