Although I’ve cooked with onions and garlic for decades, I’ll have to confess to considerable culinary ignorance when it comes to their relatives—chives, leeks, shallots, spring onions, scallions, etc. I go to the grocery and see them all laid out, but I’m not sure how they really differ, how to use them, etc. And aside from their role in the kitchen, what ornamental value do onions have?
Onions and their kin all reside in the genus Allium, part of the Amaryllis family (Amaryllidaceae). A large genus, the alliums are “taxonomically difficult,” meaning that there are between 260 and 979 species, depending on whom you consult. Ornamental onions are often just referred to as “alliums,” partly because the scientific name is actually easy to pronounce.
The common edible onion, Allium cepa, appears in three different colors—yellow, red, and white—but since this isn’t a cooking column I won’t go into any purported taste and texture distinctions. A couple of special onions do bear mentioning, however, even to the nongourmet: the Vidalia and the Walla Walla Sweet.
Both of these onion types are sweeter and less pungent than regular onions, but they’re not actually different varieties in the botanical sense. Instead, their unusual taste depends on the low-sulfur soils that they’re grown in. Walla Walla, Washington and Vidalia, Georgia jealously guard the names of their onions, so much so that a USDA Federal Marketing Order prohibits the use of those terms for any onions grown outside of these two small regions. Beware of any imitators.
As for those other types of Allium that appear in the grocery: Shallots are just a variety of Allium cepa, but like garlic, the head is composed of multiple cloves. In leeks (A. ampeloprasum), the white bundle of leaf sheaths just above the bulb comprises the edible portion, rather than the bulb. Scallions (aka green onions) lack a developed bulb; again, only the leaves are eaten. In chives (A. schoenoprasum) the scapes (or stems) are eaten; they happen to be the only members of the genus that are native to both the Old and New Worlds and provide a great deal of nectar for pollinators. Chinese chives is a different species, A. tuberosum, and can be highly invasive.
Around five allium species or varieties are native to Virginia. The best known to foodies is A. tricoccum, commonly called ramps, or wild leeks in some locales. A woodland plant, ramps are found primarily west of the Blue Ridge and are known for their strong flavor. A few other Virginia onion species are introduced plants and have become weeds. Among the latter group is the much-hated wild garlic or wild onion, Allium vineale, found in lawns everywhere or perhaps imparting an off taste to milk if it invades cow pastures.
Enough about the alliums that I like to eat. What about the ornamental alliums? All alliums have basal leaves, a stem-like scape growing up from those, and are typically topped by ball—umbel in botanical parlance—of several flowers in a cluster. Flowers are generally white, pink or lavender, although a couple of species sport yellow blooms.
Among the larger species, last fall I planted Allium schubertii and A. christophii, both ordered from Brent and Becky’s. I was looking for big and spectacular and wasn’t disappointed. A. schubertii’s volleyball-sized umbels of rose/purple flowers sit atop an 18-inch stalk, their open structure resembling a Sputnik from the ’50s. Somewhat more demure, christophii’s silvery-amethyst flowers sit on a softball-sized inflorescence. Both plants still look attractive weeks after flowering.
A couple of other biggies that I look forward to trying include Allium ‘Globemaster’ with deep lavender umbels atop 30-inch scapes—“the best ornamental onion I have ever tried” according to plant guru Alan Armitage—and A. giganteum, its lilac-purple flowers sitting on stalks from 3- to 4-feet tall in late spring. These tall alliums can be grown to poke up through shorter perennials to hide the dying foliage.
While the larger alliums can make a statement by themselves, the smaller species need to be planted in clumps of several bulbs. Still fairly tall at two feet, Allium sphaerocephalum’ s quarter-sized flowers start out green, then turn deep purple as the blooms open progressively down the umbel. Allium ‘Millenium’ blooms in late summer with 2-inch rosy-purple umbels. Unlike most of the spring-blooming alliums, ‘Millenium’s delicate glossy green foliage persists into the fall. This tidy 1-foot-by-1-foot plant earned the title of Perennial Plant of the Year for 2018.
If you’re searching for a particularly dainty allium to use in a rock garden, look for Allium kiinse. Only 6 inches tall, the small outfacing flowers don’t show up until October or November. Another shorty is A. karataviense, with golf ball-sized pale lilac flowers atop striking 4- to 6-inch wide, pleated bluish leaves. If you want a change from the pink, purple or white flowers of most alliums, there are a couple of yellow alternatives. Allium moly ‘Jeannine’ has a two-inch cluster of bright yellow flowers atop its 1-foot stem. Somewhat pendulous lemon-yellow flowers distinguish another species, Allium flavum.
All the ornamental alliums appreciate full sun and well-drained soil. Heavy, soggy soil can lead to rot and a short lifespan.
Enjoy your onions, be it for cooking or viewing.