Excerpt of  "Ornamental Alliums" by Carole Ottesen
For discerning gardeners, ornamental onions are indispensable additions to the spring and summer bulb display. And now’s the perfect time to plant them.

Say “bulbs” and the first things to pop into a gardener’s mind are tulips, daffodils, and crocuses. Alliums are an afterthought. In spite of remarkable attributes—showy flowers that are great for cutting and drying, easy culture, exceptional hardiness, deer and vole resistance—alliums seem to be the Rodney Dangerfields of the plant world.

This is hardly a new phenomenon. “Alliums are not so popular in gardens as on many counts they deserve to be,” wrote Louise Beebe Wilder in her 1936 classic Adventures with Hardy Bulbs. A half century later, Dilys Davies, author of Alliums, the Ornamental Onions, put it more forcefully, describing the genus as “undeservedly neglected…attracting a smallish circle of enthusiasts, plus the odd fanatic.”

It’s hard to single out one reason why these spectacular bulbs are not more roundly appreciated, but perhaps it has something to do with their culinary associations. I grew culinary onions—chives, onions, shallots, and garlic—for years before I got around to trying the purely ornamental side of the family.

I remember clearly that the first ornamental onion to come into my garden was a dim second choice. First choice had been the June-blooming giant alliums (A. giganteum) with their magnificent six-inch flower heads. I had dreamed of a flock of them, but when I learned how expensive a single bulb was, in a momentary paroxysm of parsimony, I opted for a dozen of the cheaper Persian or “tall drumstick” alliums (A. aflatunense). Thus it was that on a brilliant October day, while popping in bulbs between clumps of fountain grass (Pennisetum alopecuroides) that instead of feeling euphoric, I fretted: Why hadn’t I just bought what I had intended to buy in the first place? How could 12 bulbs that sold for the price of three be anywhere near as showy?

The following May proved those worries unfounded. Four-inch balls made up of hundreds of tiny purple florets rose on three-foot stalks through a ground cover of emerging fountain grass. Not only were Persian alliums a bargain, they were spectacular. And combining them on a low mound with an ornamental grass turned out to be a stroke of dumb luck. The drainage is good—a requirement of this summer-dormant bulb—and I hadn’t known that the grass would camouflage bulb foliage that yellows just as the flowers appear. My Persian alliums are attractive, healthy, and have returned in greater numbers every spring for more than a decade, although the flowers have declined somewhat in size. And it’s a combination that mystifies visitors to the garden who ask, “What is that grass with those amazing flowers?”

Big-Headed Alliums

Persian alliums belong to a group that I’ve come to think of as the “big-headed alliums,” an unscientific but descriptive name that encompasses some showy types of horticultural origin and mixed parentage.

One of these, ‘Purple Sensation’—to my eye identical to Persian allium but for its deep, dark violet purple color—is often listed as A. hollandicum. Crosses of Persian allium with other species have produced a bevy of beauties with attributes that blur the distinctions between species. A cross of A. aflatunense with A. macleanii produced ‘Gladiator’, a rose-purple hybrid, and ‘Lucy Ball’, a dark lilac-purple selection. ‘Rien Poortvliet’ is an amethyst-violet-flowered sport of ‘Gladiator.’
Allium ‘Mars’ is a spectacular hybrid that bears six-inch-wide lavender-purple umbels. Three to four feet tall, it flowers in late spring. ‘Mount Everest’, with six-inch-wide pure white snowballs, is an excellent tall selection.

Of course, the poster child of the big-headed alliums is A. giganteum, the one I had originally lusted after, smitten by a catalog photo of a softball-sized flower dwarfing a child. The fall after the May-of-the-Persian alliums, I made haste to the garden center and spent a small fortune on giant alliums.

Significantly larger than Persian alliums, giant alliums have celebrity presence. In the June border, six-inch balls of dark lavender florets on four-foot stems float majestically above lower-growing perennials. An equally attractive white form, ‘White Giant’, is also available. Blooming slightly later than Persian alliums, these giant alliums extend the display and cutting season.

While Persian alliums provide big, bold additions to late spring bouquets, giant alliums are bouquets in themselves. If you plant both, you’ll have two months of terrific cut flowers that bring long-lasting substance to bouquets and even preserve well as dried flowers.

These two species flower in concert with the late-spring-to-summer crowd, including Virginia bluebells (Mertensia spp.), late daffodils and tulips, honesty (Lunaria spp.), bleeding hearts (Dicentra spp.), columbines (Aquilegia spp.), Brunnera spp., peonies, and oriental poppies. After bloom, balls of quivering seed heads remain attractive while discreet foliage, amazing in plants that make such an impact, departs with courteous dispatch and little mess.

Giant allium is sometimes named, along with A. stipitatum, as a parent of the traffic-stopping ‘Globe Master’, a Guinness-Book candidate with blooms eight to 10 inches across. Other sources credit this cultivar’s size to the species with huge heads of loose, shaggy florets, the star of Persia (A. christophii, formerly A.albopilosum). Star of Persia bears eight-inch balls of metallic blue-violet florets on rather disproportionate 15-inch stems. Thriving in a hot spot, it is said to require rather alkaline soil and, like most alliums, demands excellent drainage.

Bigger, but skeletal in flower is A. schubertii, which seems too outrageous to be real—an explosion of rosy florets caught in mid-air on an 18-inch stem. I always think of this one as “the tumbleweed allium,” because I have read that in its native places—North Africa and central Asia—the dried flower heads eventually break off the withered stems and, blown by the wind, cast their seeds abroad as they roll. Drainage is critical for this summer-dormant allium; I have lost several to long, hot, wet summers. Prudent souls might lift these bulbs after flowers have faded and replant them in fall.

Photo of Allium afflatunense by Ken Meyer;
photo of Allium schubertii by Carole Ottesen.
Click on images for larger version


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