Fired up to grow your own? Then here's a little novelty
ANOTHER LIFE:IF EVER A SUMMER did a marketing job for the polytunnel industry, it was this one. Even here on the west coast, mostly spared all but the gentlest Irish epithets for rain, it has taken the silvery crucible of plastic to focus what little was seen of the sun.
I think of novice gardeners in the east and south, fired up to grow their own for the first time, and trust that, somewhere in the back-garden alchemy of seed and soil, they have forged enough earthy optimism to carry them on to next spring.
A little novelty lifts morale. Quite the biggest plant in the tunnel just now – not the tallest one in my painting, which grew last year’s winter squashes, but towering almost as high and elbowing me aside with even bigger, softer, floppier leaves – is Smallanthus sonchifolius, otherwise yacon, the sweet underground “pear” of Peru.
“Pear” is one evocation, but this juicy tuber, growing in clusters the size of big baking potatoes, also offers the tang of early apple and crunch of watermelon, along with perhaps a hint of celery. As fruit or vegetable it has long been a thirst-quenching staple of the hardy Andean peasantry, and it seems as near as I am going to get, now, to seeing Macchu Piccu.
Yacon was first brought to central Europe a few decades ago and trialled as a possible new fodder crop and alternative to sugar beet. Given its highland origins, a cooler outdoor climate made few problems, but a tunnel provides the regular watering and long growth season that ensures the biggest – sometimes phenomenal – yield per plant.
The tubers’ zingy flavours and “mouth appeal” should long ago have given yacon pride of place in more exotic restaurant salads, but problems of supply and life in storage have put a brake on its career. What could change that is promotion of yacon’s quite distinctive plant chemistry, offering sweetness without weight gain or raised blood sugar.
It is exceptionally high in fructo-oligosaccharides, a sugar low in calories and generally good for the digestion, and the juice can be concentrated into something temptingly close to honey or maple syrup. Thus, to quote one university research paper, it offers “nourishment with a high potential for diabetics and overweight and obese people” and certainly an improvement on the fattening American corn syrup that saturates so many processed foods.
Yacon is a favourite with Klaus Laitenberger, author of quite the best manuals so far for Irish vegetable gardening and “an experimenter by nature” in his tunnel in Co Leitrim. He once grew 100 different tomatoes and subjected every visitor to a taste test. (The sweet cherry Sungold came out best, and were the first to ripen for me this year.) It was his enthusiasm for yacon that had me cadging a few “seed” stem tubers, still most difficult to find. The few suppliers in the UK quickly sold out this year, so December, as the crop is lifted, may be the time to go searching online.
Klaus added, generously, a handful of another Andean tuber, Oxalis tuberosa, or oca, the highlanders’ most widely grown root crop after the potato. It is daylight sensitive, and at our latitude it needs polytunnel or greenhouse to give it the right length of season. It grows in low, bushy clumps, like wood sorrel, on the sunniest side of the tunnel, and I wait for the promised yellow flowers of late summer – this and the lemony tang of its tubers at the far end of the year.