Alliums Ornamental Onions Pop In The Flower Garden

If I told you there was a spring and summer flowering bulb that deer would ignore, and it wasn’t a daffodil, could I interest you? What if I told you that the same bulb had virtually no insect problems and was close to disease free? Would that perk your petals up? And if you’re one of those gardeners who needs to have something unique or the only one of its kind on the block, would that blow your blossoms? How about a bulb that will produce flowers that are so spectacular that people walking down the street or walking by will stop and marvel at your marvelous umbels? Well, if you’ve answered yes to any of the above then you need to be thinking about onions. That’s right, onions. But these are ornamental onions, and to make them a bit more palatable we don’t call them ornamental onions, but Alliums.

The sad fact is that for most gardeners the closest that we come to cultivating any of the plants in this tribe are those who grow onions, chives and garlic — all relegated to the vegetable garden or seen as weeds in the lawn. Some, slightly more adventuresome, will pop in a few bulbs of Allium giganteum whose globe-like flowers burst into the spring garden like fireworks.

Alliums are not just for the spring though. There was a spot at work where a drift of Allium flowers appeared late every August and a couple of weeks into September. One might be tempted to pull this out as an invasive grass as it grew in a wide bed of Vinca and for a short while it looks out of place. But once the grassy stems have emerged, numerous thin green spikes appear though the Vinca. A small green umbel begins to form as the spikes elongate to about 15 inches and the umbel opens to reveal a golf ball sized mass of starry white flowers with golden anthers. This is Allium tuberosum, or garlic chives, and is one of the last Alliums to flower.

One reason why we don’t use Alliums or ornamental onions in the landscape to a greater degree is simple ignorance. The use of these plants in the landscape is slightly more than a century old. In the 1936 edition of Louise Beebe Wilder’s book “Adventures with Hardy Bulbs” she observed that the gardener is missing out on “a quantity of valuable and varied and easily grown material that it is a mistake to ignore.” Another point is that they do famously well in our sandy East End soils.

Suggesting that its scarcity in flower gardens might be due to fear of a strong smell, Ms. Wilder noted that an onion smell “is apparent only when the stems or leaves are bruised” and went on to point out that, “the blossoms of some … have the fragrance of Violets and other cherished blooms.” Due to a quarantine on foreign plant material in effect in the U.S. throughout the 1920s and 1930s, Ms. Wilder’s catalog of Allium bulbs consisted almost exclusively of varieties and cultivars obtained through her personal trading with correspondents.

Today’s gardeners are much more fortunate as we now have a wide assortment of Alliums available commercially with more than 30 varieties found in recent catalogs. Very few are wild collected, and most are grown in the Netherlands and in Turkey. But home gardeners, with some investigation, can find the seed or bulbs of nearly 100 varieties — and more if you get seed distributions from hardy plant and alpine gardening societies bringing the possibilities closer to 200 species. Remember, these are not simple, single spiked onions of washed out blue. The colors of blooms range from the purest white to the deepest purple and include cream, yellow, pink, red, blue and even neutral earth tones. Heights range from a couple of inches to 4 and 5 feet tall and everywhere in between. In addition, there are ornamental onions that can be used in rock gardens, as potted plants, for forcing, in the perennial border, in wet locations — and there are some to avoid.

Allium bulbs are generally planted in the fall (though spring and summer are the times to scout out the ones that you want to add to your planting list). October is best but in many years you can get away with plantings as late as November. The blooms appear from May to late August flowering in umbels, or clusters of flowers sprouting from the same point. The umbels can be densely packed in fuzzy spheres, as found in A. aflatunense, A. albopilosum and the monster A. giganteum, or loosely tasseled as in the dwarf species A. moly and the delicate A. neapolitanum.

Some contemporary garden designers prize Alliums not only for their colors, but for their interesting shapes and superb textures. They add engaging early summer accents in grassy or wooded areas, around shrubbery and to many manmade landscape features. Their combination of color and texture offer compelling companions to many other June-July bloomers, especially roses and lilies. The shorter varieties such as A. moly and A. oreophilum, A. neapolitanum and A. karataviense are excellent choices for rockeries.

Taller varieties such as A. aflatunense, A. giganteum and A. sphaerocephalon make interesting additions to the back of the border and most Alliums make excellent cuts with a very long vase life. Alliums make beautiful dried flowers that can be enjoyed all year. The time to start the drying process is when they are in full bloom. For best success, water the plant thoroughly the day before. The next morning cut the flower stem at the base, bring it inside and set it in a vase with three-quarters inch of water. Place the vase out of direct sunlight and allow the flower head to dry out. After 10 days you can use it in crafts or flower arrangements.

A. neapolitanum, a 15-inch species with delicate white flowers, has the most delicious fragrance of the Alliums that are now available at garden centers. It makes a wonderful cut flower and can be easily forced if overwintered in a cold frame or planted in a pot so that it can be lifted and brought indoors in late winter. This species may be a bit of a challenge to you since it is only hardy in the most perfect of settings. As the name implies, it is native to Italy. Mulch it well.

As a rule, these onions that make you smile prefer a sandy soil in full sun or light shade. The bulbs should be planted twice their own diameter deep and should be spaced generously as most will naturalize to form large and beautiful clumps of flowers over the years.

Seed catalogs list up to a dozen varieties of Allium that you can start from seed, but virtually all are frost germinators and should be seeded in early fall, set outdoors in a cold frame or seeded and planted in plastic pots for early spring germination. I had some spectacular success with seed that had been “lost” in my refrigerator for three years. The seed was sown in the greenhouse in December and they bloomed in pots in late May. One of the best references on Alliums is by Dilys Davies, “Alliums, The Ornamental Onions” (1992, Timber Press, 168pp with color & B&W photos and drawings).

In garden centers you’ll find about a dozen types of bulbs available and a quick rundown follows. For a wider selection and for more unusual varieties try the White Flower Farm or brentandbeckysbulbs.com (over 25 varieties) as well as others.

Allium aflatunense (native to Iran) has dense spherical umbels of starry lilac-purple flowers (the puffball effect) on stems 2 to 3 feet tall. Blooms in May and for the best effect plant in clusters of 10 bulbs or more. Two favorites are Lucy Ball with dark lilac flowers and Purple Sensation with a violet-purple flower. This one has the same qualities as the 4-foot giganteum, but is only 3 feet tall.

A. albopilosum (Turkestan) produces 10-inch flower heads of shiny star-shaped silvery-amethyst florets on 2-foot stems. Blooming in June this plant is also called “Star of Persia.”

A. giganteum (Siberia and Himalayas) is as stupendous as its name suggests, with enormous 6-inch puffballs or purple-mauve florets atop 4-foot stems. Blooming in late June or July, this bulb naturalizes well in tall grass and should be planted in groups of three or more in the garden. Plantings can also be made in rows in the cutting garden.

A. karataviense (Turkestan) is noted for its low-growing plumpish profile and khaki coloration, has fuzzy-looking beige-pink flowers in an umbel up to 12 inches across on stiff 8-inch stems with spotted gray-purple leaves.

A. moly (S. Europe) is commonly regarded as “the golden garlic,” with dense umbels of bright golden yellow flowers on 12-inch stems. A terrific naturalizer, its leaves are distinctly blue-green to beautifully set-off the flowers which appear in June.

A. cowanii (Western Asia) is similar to A. neapolitanum with larger white flowers on 15-inch stems and flowers in May. It is hardier than A. neapolitanum.

A. oreophilum (Turkestan) has deep carmine-pink flowers on 6-to-10-inch stems and flower in June.

A. rosenbachianum (Bokhara) produces massive galls of purple-rose flowers in mid-May on 3-foot stems.

A. sphaerocephalon (Asia Minor) has small, compact umbels or reddish-purple flowers on 2-foot stems. With its tight, handsome look, this Allium has earned the name “drum stick Allium.” It’s excellent for cutting and drying and it blooms in July.

Keep growing.