Fireworks rise, burst, and are caught at their crescendo. The alliums are in bloom. Across the garden, they soar and sparkle. These stunners could easily steal the show. Yet surprisingly, they do some of their best work not alone but in ensembles. Interspersed with perennials, shrubs, and trees, alliums pull their garden companions together, forming groups that are far more engaging than the individual parts.
Ornamental alliums (close cousins of edible ones such as onion and garlic) are a varied bunch. The flowers can be spiky or smooth, loose or tight, flat or round, less than a quarter of an inch in diameter or larger than a grapefruit. Their blossoms can be brilliant or soft purple, lilac or rose pink, true blue, silver lavender, pale green, or pure white, and they hover atop stems that rise anywhere from a few inches to more than four feet off the ground.
Most alliums bloom in mid-spring or summer, initiating a generous, and reciprocal, relationship with companion plants. As holders of the garden spotlight, alliums are able to boost the visibility of their neighbors; in exchange, alliums receive camouflage where they need it most: at ground level. Like many bulbous plants, alliums have leaves that can turn scraggly when their flowers bloom -- one reason why many gardeners wisely interplant alliums with perennials. The latter ably cover the limp foliage at alliums' feet without obstructing blooms up top. Peonies, daisies, and geraniums are popular choices, as are shrubs.
The striking beauty of alliums often appears even more dramatic indoors. Arrangements can be minimalist and modern or lush and romantic, but they are always captivating, thanks to the plants' graceful, towering stems and otherworldly blossoms. As they fade, many alliums retain wispy frameworks of their flowers. The seed heads have a shadowy prettiness that sustains the plant's allure long past its peak, whether the setting is a vase or a garden.
Spring-flowering bulbs should be planted in fall so they can establish their roots before winter. Even in areas as warm as Zone 8, alliums will thrive as long as they have a well-drained spot that is rich in compost and receives at least a half inch of water each week from early spring through the bloom period. Pests and animals are rarely a problem, as the bulbs taste unsavory to them. The plants also are remarkably disease resistant. Most alliums love sun, but Allium 'Globemaster' and A. karataviense 'Ivory Queen' are two that can tolerate partial shade, making them fine companions for hostas and euphorbias.
Bright purple and pink alliums look particularly vivid next to chartreuse or silvery-green foliage (two excellent partners are Physocarpus opulifolius 'Dart's Gold' and Euonymus fortunei 'Variegatus). And all of the various white alliums are especially stunning when positioned next to pale purples or intense plums. A. karataviense 'Ivory Queen' or the much taller A. stipitatum 'Mount Everest,' for example, can help show off the lilac flowers of dame's rocket (Hesperis matronalis) or the rich, dark foliage of Cotinus coggygria 'Royal Purple.' It's planting combinations such as these -- and the ones you're bound to dream up -- that ignite the most exciting sparks of all.