Harvest tasty topanimbour tubers all winter long.

12/06/2001
Harvest tasty topanimbour tubers all winter long.

Here's a riddle: What plant is a hardy perennial, a carefree flowering hedge, and a tasty vegetable all in one?
Answer: Helianthus tuberosus, or the Jerusalem artichoke (topanimbour in French). This curious plant is one of what the French call les légumes oubliées--or forgotten vegetables, those unusual, "minor" vegetables which were appreciated in antiquity but are rarely grown today. Currently these are all the rage in France, with great chefs doing interviews on their latest creations using these formerly unfashionable vegetables and fruits.

In France, the topanimbour has long suffered from undeserved ill-repute. Writing in 1650, Philibert Guybert blamed this humble plant for causing all sorts of physical ills, including vertigo, testicular pain (!), psychosis, and flatulence. (Only the last of these has any basis in reality.) This bad press seemed to follow the Jerusalem artichoke for the next several centuries, when it was grown primarily as animal fodder. But I'll bet not a few of the tasty tubers found their way into the cooking pots of the poor and thrifty French country folk.

In World War II, the French renewed their ill associations with this plant when the occupying Nazis commandeered all the potatoes the country was able to produce, leaving only the lowly topanimbour for the French themselves to consume in place of their beloved pommes de terre. Today the tubers are still spurned by those who retain this memory, or remember their parents reciting it.

In fact, the Jerusalem artichoke is probably of North American origin, most likely coming to Europe with captive Native Americans who were forced into passage as curiosities for European spectacles (traveling shows). The Italians call it girasole del Canada, and girasole became corrupted in English to "Jerusalem," for the plant itself has absolutely nothing to do with that part of the world. The "artichoke" part of the name comes from the resemblence in taste between this tuber and the base, or heart, of an artichoke.

The similarity of flavor is no accident, as the two vegetables share a high glucide content--8 to 10%. This is a form of sugar undigestible by humans, making Jerusalem artichokes excellent food for diabetics and rendering it considerably lower in calories than the potato. Your body simply can't access all the calories in the Jerusalem artichoke, making it sort of the "Olean TM" (the much-touted, undigestible synthetic "diet" fat) of the vegetable world. However, just as some unlucky dieters have found that consuming synthetic fats may cause digestive difficulties, it is the indigestibility of glucine that is probably responsible for causing flatulence in an unlucky few. While we can't digest glucine, some of our intestinal flora can.

But back to the plant itself. Jerusalem artichoke is a huge plant, often growing 8 feet tall and spreading by means of its underground tubers, which are the part you harvest to eat. It has rigid, robust stems which never flop, and the entire plant is covered with rough hairs, making it immune to insects. In mid-autumn, this hardy sunflower reminds us that it is just that, erupting into masses of single, golden sunflowers which are attractive to butterflies. In parts of the country where the season is long and hot enough for the plant to form seeds, it continues to attract birds all through the winter.

Jerusalem artichoke makes a spectacular hedge in the potager. By September it has reached stately proportions, and its flowering stems wave gracefully in the wind. It is extremely dense-growing and so makes an ideal screen for an unsightly part of the garden.

Its culture couldn't be easier. This plant will grow in just about any soil. Don't add anything more than a bit of compost, as too much nitrogen decreases the size of and causes irregular tubers. You may want to move the location of the patch from time to time, as the enormous vigor of the plant can exhaust nutrients in the soil. Because of its spreading nature, you'll want either to install barriers in the soil around it, or better yet, plant it where you can mow around the patch to control spreading shoots.

In mild climates, plant the tubers in late fall; colder zones warrant a spring planting. Place the tubers in the soil just as you would a potato, about 18 inches apart and around 3 inches deep. One or two cultivations around the young plants will suffice, as the plants quickly outstrip in vigor any weeds around them.

The Jerusalem artichoke starts to form tubers when daylength shortens. Harvest usually begins in early October. However, only dig up an amount sufficient for immediate use, as the best place to store the tubers is right where they are--in the ground. Their thin, fragile skin causes them to shrivel quickly in the refrigerator. Before freezing weather, mulch them well with straw or fluffy leaves, and you can continue to dig and enjoy them all winter long.

Leave the stems standing over the winter; birds love to perch and shelter in them. In early spring, cut them and use them as one-season supports for climbing peas and flop-prone perennials.

Topinambours can be cooked in any way that you would use a potato, with a lighter, less starchy, and nuttier-flavored result. Raw, they are delicious and have the juicy, crispy texture of a water chestnut.

Now, see our Dans la cuisine page for a creative way to cook this delicious and unusual legume oubliée.

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