If you really want to grow kumara (sweet potato, Ipomoea batatas) productively, you need to give it some decent sun and plant in an orderly fashion in rich rows or round mounds. It will grow well enough in poor soil in the shade and form a decent ground cover (in summer), but it won’t put anything like the same amount of saved energy into nice edible tubers. It all makes sense when you think about it; and it’s almost as if the plant were doing some thinking about it too. In the shade, the plant ‘thinks to itself’ that it is best off if it musters whatever energy it can and invest it in long searching vegetative vines and send them off to find a sunnier place; tangled up in itself and others, up trees, up the fence, over the fence, wherever. Kind of like most of my twenties – off on an adventure seeking some good times over the horizon and setting next to nothing aside for later. If placed in full sun on the other hand, it ‘realises’ that it is on a pretty good wicket right where it is and sets about putting away some savings in the form of solid starchy investment.
As a grower, I should theoretically be like a conservative bore with no time for the frippery of the shady gallavanters and turn my back on them in favour of hard-working kumara families in the sun. I’m not sure why, but I somehow feel that the analogy is drifting a little political, by the way. I should then harvest (tax) those in the shade as much as they will bear, believing that if they fail as a result then they just weren’t cut out for it; but ensure that my harvest of those in the sun might seem deceptively as if it was their welfare more than my own that was my aim.
Well, I don’t vote that way, and I’m not gardening that way as it turns out, at least not with kumara. I foster it less as a crop than as a groundcover ornamental in the long shady garden down the side of the house where some subtropical fruit trees and passion vines are also plying a not (yet) particularly fruitful trade. It is not just shady along there, but poor, because I broke the cardinal rule of planting before I properly improved the soil (sand actually, I am on an actual sand dune) and there is also a steady sneaky pilfering of nutrients by the neighbour’s established trees. But still, the kumara hangs out, a little scrappy and certainly straggly, especially in winter, amid a ragtag bunch of Vietnamese mint, lemon balm, parsley (which grows quite delicately, looking like chervil, in the shade), sorrel and some creeping thyme. In winter, some baby bok choy seeds cast around do a small and slow job of filling in some gaps in place of the withering kumara as a surprisingly nice ornamental, right through to some lovely spring flowers if left uneaten.
And I don’t really harvest the kumara properly speaking. I just bandicoot a little. The verb ‘to bandicoot’ is pretty much self-explanatory, assuming that you know what bandicoots do (long-nosed ones, Perameles nasuta, around here). They sniff about, scratch a bit of a divot and stick their snout in, making a distinctive conical hole with it, and pull out a little food from here and there. Admittedly, for real bandicoots, it is mostly invertebrates, but it also includes the occasional tuber. In addition to kumara, bandicooting is particularly well suited to getting in early at some new potatoes (Solanum tuberosum), and it also works with a lot of other tubers as well (Queensland arrowroot, Canna edulis, being the main one of mine)
Unlike bandicoots, I then also re-enact the birth of farming with my kumara. With a tuber pulled out, foraged more than farmed, I dig down a little further into the sand (which goes off to the ‘soil factory’ that is the chook run, to be enriched with chook-turned compost and poo), replace it with compost and some kumara stem dipped in rooting powder, and the whole process can just keep rolling on; pretty unproductively because of the location, but with a lovely sustainable aesthetic to it. With a bit of welfare that includes short-term feeds (a disproportionate share of worm farm juice so that those in the sandiest spots almost grow hydroponically) and long-term investment (the sand-compost replacements), conditions have improved markedly over the first year out there in the Bohemian bandicooting quarter of the garden. This summer, I am expecting quite a show.