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The Homeowners Column
Growing Ornamental Onions
State Master Gardener Coordinator
If any group of plants needs a marketing plan, it's ornamental onions. Onions do not conjure up visions of beauty unless they are deep fried on a platter. Ornamental onions are often listed under their botanic name, Allium, as an attempt to lose that onion stigma no doubt. Alliums offer tremendous variety. They send up a flower stalk topped by some sort of sphere of small flowers. The flower stalks might be three inches tall or up to four feet tall. The spheres might be a few inches in diameter to 12 inches across. Flowers vary from shades of pink and violet to blue, white and yellow. Most alliums are easy to grow and winter hardy perennials here in Illinois.
Alliums are bulbs just like the edible onion and will offer their aroma only if you happen to spear one. Like other bulbs they should be planted in September and October in well-drained soil in full sun. Alliums definitely need companions. One allium looks lost so plant multiples. Also most leaves die back during or after flowering so tuck alliums in groundcovers or near other perennials that will mask the open space. The leaves die quicker than tulips and daffodils so you don't have to contend with the lingering dead leaves. Since the mass of leaves tend to be much shorter than the flowers, alliums are easy to tuck.
Alliums are blooming now so get out to your favorite gardens and start taking notes. One of my favorites is Star of Persia, Allium christophii. Just imagine fireworks without the noise but with the ooohs and aaahs. You know that kind of fireworks that forms a ball with zillions of stars on the outside rim. That's Star of Persia. The flower sphere is 10 to 12 inches across in a lovely metallic violet and stands about two feet tall. 'Globemaster' is a fine cultivar. The flower spheres are about six inches in diameter with deep lavender flowers. They put on a show for several weeks. Even the seed head is attractive well after the flowers have faded.
Turkistan Onion, Allium karataviense, is grown for its leaves. The large four-inch wide leaves are a lovely blue gray with a hint of purple. At six inches tall they are a real knockout for front of the border.
There is no cheerier color than the yellow of Lily Leek, Allium moly. At a foot tall Lily Leek is nice in the front of the flower garden. The bulbs multiply and can be divided to add to other parts of the garden.
For late season interest there is the Japanese Onion, Allium thunbergii. The tufts of leaves persist all season and just as other plants are contemplating winter, the Japanese onion shows off its starry purple flowers. The flowers are sweetly fragrant.
The Giant Onion, Allium giganteum, is just as its name implies. The flower stalk can reach four feet tall. Giant Onion comes with a long drum roll and great anticipation. It takes three to four weeks to see the flower once the stalk appears. It's well worth the wait but tuck several among other plants or they will seem naked. The leaves die before the flowers appear.
This year plan on venturing into the wonderful world of alliums. They are sure to get a "what is that?" from your garden visitors. Check out the Master Gardener's Idea Garden on South Lincoln Avenue in Urbana for several Allium species.