The first time I saw the odd little tubers labeled "Jerusalem Artichoke," they were shrink-wrapped in plastic next to the fennel bulbs in my supermarket. I bought them out of curiosity, liked their taste, and saved two or three to plant. A few years later I was harvesting enough tubers to feed the whole neighborhood.
These undemanding perennial sunflowers will grow in nearly any climate and are insect- and disease-free. They send up multiple stalks, six to 12 feet tall, and form an attractive screen. The cheery blossoms make great cut flowers. Bloom starts in late summer, though under some conditions (not enough light or early frost), some varieties may bloom sparsely or not at all.
In the fall, you'll enjoy an abundance of nutritious low-calorie tubers with an unusual nutty flavor. A 15-foot row (1 1/2 to two pounds of seed tubers) will produce at least a half-bushel of tubers. A single serving (100 grams or roughly two large tubers) delivers 2.3 grams of protein, 16.7 grams of carbohydrate and a rich supply of minerals (phosphorus, iron and calcium), not to mention 20 I.U. of vitamin A.
And sunroots are good eating! Raw, they are crunchy, with a slightly sweet flavor. You can cook them in casseroles or stews. Or they can be creamed, pureed for soup, curried or simply mashed, fried or baked like potatoes. Thinly sliced, they're like water chestnuts in stir-fry dishes. And they make a satisfying salad diced with onion, celery and a bit of cucumber.
The tubers store well through the winter in a refrigerator or root cellar. I've kept them that way from March to September. Or, you can leave them right in the ground and harvest until they start to sprout in spring. The longer I've grown and researched this plant, the more I've wondered: Why haven't all gardeners discovered this great vegetable?
Maybe the name has something to do with it. Jerusalem artichokes certainly don't look like artichokes, and they aren't related at all. "Sunchokes" isn't much better. A more appropriate name that seems to be catching on is "sunroot." This is an accurate description, for the plant, Helianthus tuberosus, is a species of sunflower that spreads by rhizomes bearing delicious fleshy tubers at their tips. These very hardy plants originally grew in a wide belt stretching from Canada south through the middle of the U.S. to the frost-free line.
It's crucial to choose the location for your sunroots wisely, for the plants spread with abandon. Any little tuber left in the ground will sprout the following season. My plants have even pushed up and broken the edges of my asphalt driveway. Metal edging or boards buried at least six inches in the ground will curb the wandering rhizomes. Alternatively, you could try to harvest all the tubers every year (no mean feat!), then replant next season.
For large, high-quality tubers that are easy to harvest and clean, give plants a sunny site and loose soil of medium fertility. If your soil is heavy clay, add lots of decomposed plant material to loosen it. Plant whole tubers, or cut them into pieces, leaving one "eye" in each section. Plant them at least a foot apart and about four to six inches deep.
To harvest a crop the first season, plant as soon as the ground can be worked in the spring up North. In the South, you can plant into the early summer. Gardeners anywhere can plant in fall for a crop the following year. Some mail-order companies ship only in early spring, others ship in fall, and in some cases you can specify your preference.
Lightly cultivate and mulch the plot when plants are young to save water and keep the weeds down. Once established, the sunroots will rapidly outgrow most weeds. Sunroots are drought tolerant. In my arid Rocky Mountain climate, I receive only 15 inches of rainfall a year. The sunroots needed thorough irrigation when I first planted them. Now I water only occasionally throug the summer. In the Northeast and Midwest, mulched sunroots seldom need supplemental water. Diseases and insects aren't a problem with sunroots. In the winter, slugs and voles may feed on them, but usually don't do serious damage.
The first hard frost fells the plants, but I've found it best to let the tubers cure a bit in the ground. I cut off the dead stalks about six inches above the soil so the plot doesn't look too messy, then wait two weeks to dig. Uncured sunroots have a raw "green" taste. During the curing process, however, the carbohydrate insulin begins to break down into sugars, resulting in the sweet, nutty flavor that is so enjoyable. The intestinal discomfort or upset the tubers have been known to cause in some individuals may be related to eating tubers that are not fully cured.
Where frost seldom occurs (zones 8 through 11), the plants can be forced into dormancy by cutting the stalks down in the late fall. I gave some tubers to my sister who lives in Phoenix, Arizona, where summer temperatures can hit 120° F, and they grew and produced normally. She confesses that she didn't follow any particular schedule, but when the plants started looking "discouraged" she cut them off, waited a few weeks and then dug the tubers. After a rest, the plants grew up again, as vigorous as ever.
After harvest, clean and dry the tubers, then store them in plastic bags in the refrigerator. Left out at room temperature, they lose moisture quickly and become limp. They cannot be re-crisped by soaking in water.
In areas with moderate snowfall, the easiest storage, however, is right in the ground where they grew. I usually dig enough roots for a few weeks' use, then cover the bed with pine needles, leaves or straw -- six inches is adequate for our winter lows of 0° to -15° F. I lay old window screens on the mulch to hold it in place, then just lift them to uncover part of the bed and dig whenever I need more.
To prepare sunroot tubers, peel, scrape or scrub them with a stiff brush. If they are to be baked, leave the skins on. They tend to discolor quickly, so if you aren't planning to use them within an hour, give them a quick dip in water acidified with lemon or vinegar. Don't cook sunroots in a cast-iron skillet or pot -- the chemical reaction causes the tubers to turn black.
Many seed companies offer just one sunroot, identified only as "Jerusalem Artichoke." Judging from the illustrations, they are either French Mammoth White or Stampede, the two most common varieties. Now there are newer varieties that are narrower and smoother, making them much easier to clean and slice. Some are colorful, too. Most sunroots require a growing season of about 125 days.
'Dwarf Sunray'. A shorter variety that flowers freely, so is quite attractive in the flower border.
'French Mammoth White'. Knobby and whitish; round to oblong in shape.
'Fuseau'. Smooth, long and shaped like a yam. An early variety.
'Golden Nugget'. Smaller than Fuseau, with golden skin.
'Long Red'. Like Fuseau but with striking maroon-red skin.
'Smooth Garnet'. With deep red skin and a blocky shape.
'Stampede'. An 90-day variety that bears large knobby, roundish, white tubers.