Sweet potatoes and some sweet sweet potato seed

Slips ready to be potted

Summer's here! Well, that's what it feels like at least. We've been having an unusually warm May here, with a monthly average some 3°C higher than usual and extended periods of hot and sunny weather. As a result, the garden has gone into turbo-mode and I've already managed to plant most of the sweet potatoes. Usually the beginning of June is a more reasonable time for this, though I never seem to have the patience to wait that long. Now though, some are already starting to put out new growth, so my impatience is actually paying off for once. I have a bunch of latecomers that are refusing to put out slips, but with tropical weather forecasted for the coming week, they'll catch up soon I hope. Barring some serious force majeur, that means I now have a final list of the varieties I'll be growing this year:

1. T65 - reliable producer, does not flower.
2. Georgia Jet - should be a reliable producer, but did badly for me last year. I obtained what I hope is a better strain, so let's see. Should flower easily.
3. Purple - (I called this Nordic Purple before, but I'm pretty sure it's the same variety that is elsewhere known by the name Purple) - purple-fleshed variety, not very productive but flowers profusely.
4. Bonita - only had one plant of this last year, so it's hard to say how productive it was, but it flowers.
5. Burgundy - same as with Bonita, plus the tiny tuber I managed to overwinter is just starting to put out slips. Flowers.
6. 'Nordic White' - unknown white-fleshed variety, fairly productive here, and flowers.
7. 'Nordic Orange' - medium productive, but I'm not sure if it flowers. I thought I saw some flowers on it two years ago. If it doesn't flower this year, I'll drop it.
8. Mystery - a Georgia Jet mutant, haven't grown this before, but if it's anything like Georgia Jet it should flower easily.
9. ? - a complete mystery this one! 
10. Bunduguza - starchy white-fleshed African variety, lowish yield, no flowers.
11. Burundi - starchy yellow-fleshed African variety, lowish yield, no flowers. This was the best out of all the African varieties I tested last year.

Then there's two varieties from the highlands of Papua New Guinea, a region that apparently can get quite chilly at night (relatively speaking of course, it's still a tropical area), and so should theoretically be somewhat cold-adapted. There's some hope, therefore, that compared to your average I. batatas variety, these two will feel a bit more at home here in maritime Malmö. They will join the others in the garden, provided they put out some slips soon. Both have roots, and one has a tiny slip forming, but I sure wished they'd hurry up a bit:

1. Kainantu 
2. Aiyura

I. batatas seed sprouting

And then, just as I thought I would get away with growing just 11+2? varieties this year, I received a small package with seeds. That is, proper sweet potato seeds, that rarest of things! These too are from the Papua New Guinean highlands. In practice, I suppose the chances are fairly slim that anything useful will come out of them. I generally put more faith in efforts to produce seeds under northern growing conditions, as Telsing Andrews has succesfully done last year, and as I hope to achieve myself this year. Nevertheless, a tiny chance is still a chance worth pursuing, plus it will be loads of fun to play around with these seeds. I promptly scarified some of the seeds with sandpaper, soaked them for half a day, and sprouted them. Germination rate was higher than I had anticipated, of the 35 seeds I soaked, 29 sprouted. That's 29 new sweet potato varieties, right there. Quite a bit of difference showed up in the phenotypes, with some seedlings showing intense red leaf colouring, some being completely green, and some lying somewhere inbetween. True leafs are deltoid or cordate, with a few of the seedlings having toothed edges.

About half of the seedlings

The batata battle plan for 2016 then: 1) Grow everything under a floating row cover for as long as practically possible, in order to speed up flowering. I've given this some thought and I didn't want to go the plastic mulching route just yet, I'd prefer to get seeds without too much 'cheating' technologies. Call me a botanical luddite! 2) Evaluate varieties for flowering onset, potential seed-set, and yield. 3) Share flowering varieties with collaborators in order to increase the chances of seedset under nordish conditions. 4) Acquire more flowering varieties. 5) Repeat.

 As simple as that!

Bloom for me, mirabilis expansa

Mauka seedling, Spring 2015

I realize that a status report on last year's mauka cultivation is long overdue. I was holding off this post hoping that I would be able to invoke your envy with some pictures of my magnificently flowering mauka, but alas, the Inca gods refused to bestow this pleasure upon me. It might very well be that I angered them somehow. As you will remember, mauka combines the unfortunate characteristics of being frost-tender and flowering under short-daylength conditions, right in the middle of the European winter. I therefore brought in two mauka plants (one Roja [that I had mistakenly labelled CIP208001 before] and one Blanco) in November with the intention to induce flowering and produce seeds. Let me clarify that I don't possess the best of conditions for overwintering plants indoors. I live in an appartment that gets quite dry in winter and the only outdoor space I possess is a 2sqm balcony (that I manage to cram full of plant starts in spring). Greenhouses, spare rooms, cold banks and root cellars are utopian concepts to me. If anyone would like to make me a present of, say, a farm, that would be very much appreciated...

Mauka root close-up, with wireworm damage

Anyhow, the maukas got a rough ride through the winter. Shortly after I brought them in, both plants got infested by aphids, which in a warm, dry and predator-free environment is prone to spiral out of control pretty quickly. Since we don't usually get frosts that often here in November and December, I figured I could more or less control the aphids by keeping the plants out on the balcony as long as possible, and just transporting them inside whenever a frost threatened. This worked pretty well for a while, but then one day in December (I guess you see where this is going..) we had a rather violent storm that pretty much blew the foliage to pieces, leaving behind a sorry-looking, bony mauka skeleton. The plants were undeterred however and quickly sprouted new leaves indoors. Then I was travelling over Christmas and New Year's, and upon my return I discovered that my absentee watering regime had failed me. Again, both mauka's lost their entire foliage, but they weren't dead and again resprouted leaves, although much less decisively than the first time. A plant that takes this much abuse definitely has my respect, though I would rather have avoided it.

But then there they sat, during January, February, and March, with no signs at all of flower buds appearing. Frustrating. I dutifully ferried them between the balcony and the living room, gave them all the love and attention I had to give (well kind of, anyway... the Roja plant eventually died somewhere towards spring, I'm not sure why...) but apparently it just wasn't enough for Pachamama and colleagues. The mauka flowering code remains uncracked, for me at least. I've now planted the Blanco in the garden together with its siblings. I might give it another shot next year, or else I'll try to lure a helpful greenhouse owner into adopting a mauka plant or two for the winter. Any volunteers?

Mauka Blanco

Mauka Roja, 2nd year growth

Seeds are not everything of course (though I have to confess I think increasingly more of them). What my plants did produce last year was plenty of roots! Of the nine Blanco seedlings that I harvested (I left a couple in the garden to see if I could overwinter the roots in situ - the answer is no), all but one were significantly larger than the first-year roots I had harvested from my two Roja plants the year before (both of which were a meagre 150 grams). Root weight ranged from 120g to 700g, with 3 roots weighing 500g or more. I also had three Roja plants (two plants in their second year, and one cutting) that were 1kg, 1,1kg, and 30g. All in all a pretty good result, which somehow confirms my hunch that the Blanco variety is superior to the Roja in terms of yield. Observation also leads me to believe that the Roja is marginally more susceptible to (light) frosts than Blanco, though the difference is probably a matter of decimals. They will definitely need more than that if they are to stand their own against the Swedish winter.

There's plenty of roads still to be travelled for mauka and me in 2016 and beyond. Apart from seducing it to bloom sooner or later, I would also like to get my hands on the CIP208001 variety, which looks a lot like the Roja but should have much better yields. And then of course, it would be exciting to try and find some additional varieties. After all, who knows what unexplored gems are still hiding somewhere in mauka's Andean homelands...