There is something wonderful about a plant that gives you color, pizzazz, longevity, reliability, and style. Many varieties of the ornamental onion (Allium spp.) do all that, and more: they brush the mixed border with an artistic touch, dotting the garden with statuesque, floral sculpture.
Spring bulbs are beloved for their brilliance and promise of renewal. The tulips, daffodils, squill, grape hyacinths, and dozens of smaller bulbs, start the growing season with a colorful hurrah! Lilies pick up the bulb show later on, with Asiatic lilies the first to show their saturated open faces and Orientals (if they are fortunate enough to survive the rabbits) coming later in summer, broadcasting fragrance and elegance in spite of their splotches and speckles. In between all this action are the alliums, bridging spring and summer with a surprising array of color (purple, yellow, blue, pink, and white), height and flower shape (golf ball, tennis ball, baseball, softball, or the diminutive bells).
Planted in fall, at the same time you drill the ground to pop in tulips and daffodils, most allium bulbs have little problem with our cold winters. A few types might be considered “annuals,” especially if you garden in heavy clay. Alliums are native to sandy, dry soils with excellent drainage—Siberia, eastern Europe, Turkey, and the lands once known as Persia. As gardeners in Chicago have learned, good drainage has a positive effect on hardiness and can bump up a plant’s chance for that coveted “reliable return.”
Alliums have earned extra points lately due to their wildlife resistance. As members of the onion family (the ornamental, not the edible side of the family), they are shunned by rabbits, squirrels, chipmunks, and other not-so-darling Disney icons I personally am fed up with). Some cautious gardeners weave allium and daffodil bulbs throughout their lily beds as a protective barrier around the more desirable lilies in an effort to outfox the fox.
Allium flowers are long lasting and attractive, whether left fresh or dried on the stems, cut for indoor display or not. They attract butterflies, do not smell like onions (although the foliage and bulbs often do), and, when happy in their full-sun, well-drained site, can form colonies or self-seed, especially when some of the more humongous flower heads are left on the plant, creating a startling, dried flower arrangement in the middle of an otherwise verdant garden.
The largest flowers belong to Allium ‘Globemaster’. At ten inches across, they are often cleverly advertised next to a smiling child’s face. Guess which is larger? For a big round purple softball on a 4- to 5-foot stem, try a small army of ‘Gladiator’. They perform best at the back of a border or against an open fence, where they can receive a bit of protection from strong winds.
There are several smaller-sized purple varieties more suited to average gardens: Allium aflatunense ‘Purple Sensation’ is the most popular. Depending on the weather, they will appear between April and May, like splendid royal purple lollipops sprouting between clumping perennials, daylilies, ground covers or wherever else there is a good green bed to hide allium’s inevitable yellow foliage. The blossoms last for weeks and are often paired with the white cultivar ‘Mount Everest’.
Allium christophii, the star of Persia, is a most unique flower! It grows only from 1 to 2 feet (keep in mind that the diameter of the flower head can be between nine and 12 inches), in an airy, open, explosive kind of manner. The amethyst flower heads will self-seed, especially in sandy soils. Blooming between May and June, it serves as a head-turner when stuck at regular intervals in the front of the border, not unlike the effect of Allium schubertii.
Gardeners looking for a good purple or blue with less drama might consider the true-blue Allium caeruleum. Their golf-ball blooms also appear at the convenient May to June period. The purple drumstick ornamental onion, A. sphaerocephalum, offers a wonderful vertical exclamation point without the athletic ball flower head. Its tightly controlled “drumstick” flowers are dark burgundy.
For those who prefer a small, star-shaped, yellow flower, the golden lily leek, Allium moly, is a more demure, suitable choice. It appreciates the same culture of rich, well-drained soil with no winter sogginess.
The native pink Allium unifolium, however, will tolerate moist soil, and happily bloom with bunches of bell-shaped flowers from May to June.
While these plants may bloom in late spring, they are planted in late fall. The Garden's Fall Bulb Festival provides a one-stop shopping for alliums and hundreds of other bulbs. The Festival is usually held in early October.