If it weren't for Dutch elm disease, John Swenson's garden would probably still be a shady place given over to cool lawn, several viburnum bushes, and a collection of spring-flowering bulbs. But when the disease killed the seven large trees that sheltered his yard, the sun poured in and John's approach to gardening took an unexpected turn. Fourteen years later, what began as a flirtation with vegetable gardening has turned into a passion for onions. His collection of edible onions (Allium species) includes potato onions, shallots, garlic, rocambole, leeks, elephant garlic, top onions, various species of chives, and much more. Swenson grows more than a thousand varieties, making it one of the largest in North America.
Big collections rarely look like gardens. In mid-spring this year Swenson's patch in the suburbs north of Chicago looked like an Arlington National Cemetery for mice, with fog from Lake Michigan scarcely a hundred yards to the east rolling eerily across the hundreds of rows of small white markers. Among the 20 or so raised beds, there was a healthy stand of red raspberries, but not a speck of room for other vegetables.
And this wasn't even the whole collection, Swenson told me. Many of the shallots have gone north to the care of onion-breeder friends at the University of Wisconsin, and Swenson has begun farming out clusters of varieties of other sorts of alliums to members of the Seed Savers Exchange. Usually he plants a kitchen garden among all the onions, but this year there wasn't much point in that, since he spent the heart of the summer in the mountains of central Eurasia. There, with a small group of USDA onion breeders, he collected ancient strains of this valuable and pungent group of plants.
Swenson's interest in alliums awakened the first year he put in the vegetable garden. One catalog specialized in exotic varieties from Europe. In it Swenson discovered not just one kind of shallot, but three. He got all of them. And there was something called rocambole, a mystery plant.
"The catalog said something like 'we don't know whether this is a garlic or a shallot, but it's good and only $3 for 25 little bulbs.' I was intrigued and just had to have some. I planted it and became fascinated.
"I planted the tiny bulbs in spring right after the order arrived, and when the tops died down I dug them and found little solid rounds. As a long-time tulip grower, I recognized them as immature bulbs. So I replanted them that fall to see what they would do. The next year it became obvious the plants would get very big. In June, when the scapes (flower stalks) appeared, they got taller and taller and then all of a sudden took a turn toward the ground. I thought it had some loathsome disease, but then it wound up again, made a turn and a half, and straightened out once more. It was just doing its thing; nobody knows why rocambole does this. Then, when I thought it was going to flower, it began to produce a cluster of little bulbils at the top, just like the ones I had been sent originally.
"When I dug the plants, I realized that what I had was garlic, plain and simple. If the seedsman or I had just looked up rocambole in the dictionary, we would have been told as much. But sometimes it's better to learn by doing. Anyway, the nice thing about rocambole is that all the cloves in a bulb are clustered around the stalk like the segments of a tangerine. There are no little, nasty-to-peel ones in the middle like you often get with regular garlic. Plus, you get replacements for planting on the tops. When you plant the bulbils in spring, as I did at first, you get the little rounds. But when you plant in fall, you get bulbs with cloves."
Garlic remains one of Swenson's prime passions. A current project involves selecting and propagating strains of garlic that produce only large cloves the way rocambole does. Ordinary garlic does not regularly produce bulbils on top like rocambole, though some strains will bolt if they're under stress, growing a short stem topped by a cluster of bulbils. Nonbolting garlics, Swenson has found, are much better keepers.
But most strains of garlic are nonuniform, containing a wide range of types. In one 50-pound sack of garlic, Swenson was able to find about half a dozen distinct and desirable bulb types. Some were golf ball-sized bulbs with only five large cloves, four around the outside and just one in the middle. Others were really big bulbs with 8 to 10 large cloves each.
The advantage to big bulbs is that they're a lot less work for the cook, and Swenson feels that it will be fairly easy to get strains of garlic that produce only easy-peelers. He finds that garlic comes true, which means that any gardener can get good results planting cloves from the best supermarket bulbs. Locale can change the way a strain of garlic can perform, however. One of his correspondents in Oregon has two gardens, one a thousand feet higher than the other. He's found that a strain that produces six or eight cloves per bulb at the higher altitude will yield a bulb of the same size but with 12 or so smaller cloves in the valley.
A popular way to grow garlic in China, Swenson tells me, is to plant the cloves close together and deep, either in spring or fall. When the plants reach about eight inches tall, dig them and eat them, leaves and all--the flavor will be mild.
When it comes to the true onions (Allium cepa), Swenson urges gardeners to grow the kinds that divide in order to multiply--potato onions and shallots. If you save and replant a portion of the crop each year, you can avoid the extra work of growing from seed or the very limited choice available in commercial onion sets. Most multipliers are superb keepers and highly esteemed for cooking, though a few are mild enough for salads. Young plants can be pulled early for scallions, and shallot tops can be cut in spring for chives. Swenson points out that in production trials, potato onions yielded the greatest weight of food per square foot of any vegetable except staked or caged tomatoes.
Shallots and potato onions come in a range of colors (white, yellow, red, pink, and purple), sizes and bulb shapes. Potato onions tend to be flattened spheres, while shallot bulbs tend to be taller. The key distinguishing feature, however, is in how they multiply. A single shallot will always divide to form a cluster over the course of the growing season. Potato onions multiply differently, depending on the size of the bulb you plant. Big bulbs (two to three inches) will produce a cluster of smaller bulbs; small bulbs often just grow into single large bulbs.
It astounds Swenson to think that the potato onion, a valuable and common garden onion a hundred years ago, nearly disappeared from the American gardening scene. About 10 years ago some seed-saving gardeners began to promote the potato onion in gardening magazines, and a few seed companies began to sell it. Today some USDA onion breeders think it's a crop with real promise. The rare varieties, Swenson says, are available only to members of the Seed Savers Exchange, but the varieties that are currently being sold are among the very best.
Shallots have never been as popular in North America, but they've always been easier to obtain than potato onions. In Europe shallots are big business, and have long been available through importers. Swenson's current favorite among shallot varieties is 'Prince du Bretagne', which he gets from wholesalers in Chicago's copious produce market. Each shallot approaches the size of an egg. If you can't find it locally, he recommends trialing the varieties available from seed houses. The gray or true French shallot, he warns, is extremely pungent with a thick, tough outer layer and is best grown for its tender leaves.
Seed onions (A. cepa cepa) began to edge out the multiplying onions over a hundred years ago primarily because they could be increased so economically from seed. And people were drawn to the very large bulbs that seed-grown onions could produce. Today there are hundreds of varieties with a wide range of attributes. Besides being dependably large, meaty and tender, some are exceptional keepers. Others, like the 'Granex' (also known as 'Texas', 'Vidalia', and 'Maui Sweets') for the South and the 'Walla Walla' for the North, are pleasingly mild and juicy.
Swenson admits that the onions one grows from seeds or sets are not among his interests. He doesn't have time to raise onions from seed, and besides, that class of onion is receiving ample attention from a small army of plant breeders. Swenson's onions are the more perennial kinds, the underdogs of the contemporary allium scene.
For people who want to grow the seed-type onions, however, Swenson strongly recommends exploring the wealth of varieties we have today. And that means starting from seeds rather than purchasing sets. Onion sets are just tiny onions of varieties that keep exceptionally well. Growers plant the seed very close so the onions can't get very big. Swenson says you can either plant seed early in a greenhouse or cold frame to get large onions the first year or sow the seed close together outdoors in summer, to produce sets for the varieties you want. Study the seed catalogs closely, he advises, choosing varieties that match your area's day length and have the culinary qualities you favor.
Elephant garlic is really a kind of leek (Allium ampeloprasum), Swenson told me, and there are two other kinds grown for food across the Atlantic but virtually unknown here. 'Kurrat' is an Egyptian strain grown strictly for its tender leaves. 'Perlzwiebel', the pearl onion, is a kind of miniature multiplying elephant garlic grown in Germany, the Netherlands, and Italy for pickling. What pass for pearl onions in America are really white onions planted very close to keep the bulbs small.
All plants in the leek family reproduce from bulbs in an interesting way. Elephant garlic is a good case study. Cloves planted in fall produce, bulbs that are typically two inches across with four to six large cloves. The cloves are juicy and taste very much like garlic. Swenson has seen cultivars that attain the size of softballs, up to two pounds apiece with about six giant cloves. At the base of each bulb, the plant also produces a number of hard pea-sized corms. Each will produce a round--a single, spherical bulb that's solid fleshed like a garlic clove rather than layered like an onion. Cloves planted in spring will also often produce rounds instead of bulbs with cloves. Left in the ground or replanted in fall, the rounds produce cloves the following summer.
Leeks usually produce seed in their second summer. But if you cut out the seed stalk, Swenson says, the plant will produce a bulb with two or more cloves and a number of corms. Plant them and you get more leeks. 'Perlzwiebel' is a miniature elephant garlic that multiplies prolifically. Each clump gets to 12 inches across for Swenson. The harvest is a multitude of rounds--perfect spheres of solid flesh with the flavor of garlic. They range from the size of a BB up to a dime. There's no commercial source for them in the U.S., but Swenson plans to make them available to the Seed Savers Exchange.
The most widely used allium in China and Japan is A. fistulosum, sold in America in seed packets under the name Japanese hunching onion. Once established, the plant is perennial and divides abundantly to produce a steady crop of scallion-type onions that can be harvested nearly year-round. About the only time you don't harvest it, Swenson told me, is in late summer when the old stems are dying and new ones forming. The plant is quite winter hardy and widely adapted.
Its flavor is very mild and pleasant. Swenson regards it as indispensable for the well-stocked kitchen garden. Besides multiplying in the ground, the hunching onion produces beautiful flower heads followed by a generous crop of seed. Plant the seed in either fall or spring.
The Egyptian onion, which isn't from Egypt at all, is a bit of a mystery plant. It's also known as a multiplier, walking onion, winter onion, and top onion. Swenson explains that this top onion (named for the small onion sets that grow atop the stalk in early summer) is a cross between the Japanese hunching onion and a strain of the common onion, A. cepa. There are a great number of varieties, which appear to be most common on the Indian subcontinent. He theorizes that they migrated to Europe with the Gypsies, a misnomer for the Romany people. Hence the name Egyptian. These onions are common today from China to western Europe.
The leaves of many Egyptian onions are very winter hardy. Some people plant the sets deep to create long white scallions. Many strains have skin so tough that the scallions must be peeled to reveal tender white centers. Other kinds will produce bulbs up to two inches across. Many top onions are very strong flavored and some Swenson regards inedible. His favorite is a strain called 'McCullar's White', which is on the small side and relatively mild and sweet.
The garlic chive, A. tuberosum, is another of Swenson's favorites from the Orient. In America it is best known as an ornamental that flowers profusely at summer's end. The wide flat leaves are handsome and each clump produces a thick burst of shining white flowers that attract a merry host of bees and wasps.
In Japan, China, and Mongolia, garlic chives are a big cash crop. Because they flower so late, they can be cut all season. The flat, mild-tasting leaves are cut and tied into little bunches two to three times each year. In Swenson's view the plant's only drawback is that it seeds so freely it can become a weed if it's not deadheaded.
There's a small hunching onion from China that Swenson has high hopes for. A. chinense sometimes appears canned in Oriental groceries as pickled shallots. At one time it was grown on the West Coast by Chinese market gardeners. Swenson's plants came from Japan, south of Tokyo, but have proved perfectly hardy in the Chicago area. The small plant has fine, grasslike leaves. The bulbs and stems, which are the edible portions, divide prolifically and are best eaten raw like scallions. Swenson plans to increase the plant and would like to see it introduced to cultivation in this country.
Swenson's list of edible alliums goes on and on. He has several varieties of common purple-flowered chives, A. schoenoprasum, as well as a white-flowered variety that, he tells me, grows wild all around the northern hemisphere. He grows and is fascinated by some of the onions harvested by Native Americans: A. canadense, the nodding prairie onion (A. cernuum) and ramps (A. tricoccum). And he's enthusiastic about the eating quality of A. nutans, another plant that is best known here as an ornamental. A close relative of garlic chives, it has flat leaves of mild flavor and sends up attractive red-purple flower stalks in early summer. Even A. giganteum, perhaps the most spectacular ornamental onion, is used as food in its native range, Swenson tells me--a tempting notion, but at $3.50 to $6.50 a bulb it's going to be a while before I cut any into my ratatouille.
The collection Swenson has built in his suburban backyard is truly a national resource. What began as a vegetable garden has, over a decade, evolved into a combination germplasm repository and plant introduction station. It may be modest in size, but size often has little to do with impact. Seeds (and corms) are small but contain an irresistible power. Swenson's enthusiasm for the lowly onion carries that same impact. Cloudy texts in foreign languages and red tape barely slow him down. There's a lot of good eating in the world of alliums, and thanks to Swenson and his collaborators we're all a bit more likely to get a taste of it.
Jack Ruttle is a former senior editor at National Gardening.
Photography by National Gardening Association, Suzanne DeJohn/National Gardening Association (planting shallots), and Charlie Nardozzi/National Gardening Association (leeks)
Article published on June 23, 2008.