Growing Allium: The Ornamental Onion

Best Allium Varieties For The Flower Bed

Nov 1, 2017
Allium: The Ornamental Onions
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Eye-catching and easy to grow, ornamental onions, of the genus Allium, deserve a place in every garden. Fall is the best time to plant these deer- and rodent-resistant bulbs.

Every fall I am seduced into planting more bulbs. After 30 years you would think I couldn’t possibly need any more daffodils. Maybe not but that doesn’t stop me from planting more.

I can’t get enough of allium. Distant cousins of edible allium such as onions and garlic, there are over 700 species of ornamental onions to choose from. Some are tiny—only 6 inches high while others grow to be over five feet tall! Some have nodding, bell-shaped blossoms while others look like a burst of fireworks.

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Then there are the huge, round flowerheads that resemble chive blossoms on steroids!  The blooms, towering high in the air and waving globes of color at the end of long, slender stalks. Most allium bloom later than the spring bulbs so if you need an exclamation point of color to carry your garden from daffodils to peonies, look for an allium.

Deer- and Rodent-Resistent

Since they are in the onion family, rodents, rabbits, and deer leave them alone, repelled by their strong flavor. In fact, a ring of allium might serve to protect other plants from grazers.

However, the flowers don’t smell “oniony” at all; most are quite pleasantly fragrant and are a favorite with bees and other beneficial insects. Although their leaves and stems give off an oniony scent when bruised, most allium flowers are sweet-scented. They make long-lasting cut flowers and can be dried as well.

Best Allium Varieties

Most often, ornamental alliums bloom in rich pinks and purples, but some are creamy white (A. neapolitanum), sky blue (A. caeruleum), and sunny yellow (A. moly). Although most form globes of clustered flowers, others, such as A. siculum, A. triquetrum, and A. cernuum, a North American native, droop demurely.

Here are some common varieties of alliums, ranging from small to tall. I wish I had photos for them all!

  • One of the tiniest charmers is dwarf Allium oreophilum growing only 3-6 inches tall. It bears loose clusters of rose-colored, fragrant flowers.
  • Nodding onion (A. cernuum) is a North American native with bell-shaped flowers that hang from its 6-8 inch tall stems. Perfect for a sunny rock garden, they come in shades of purple and pink along with white.

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  • Golden garlic (A. moly) ‘Jeannine’ bears 2 to 3 inch wide clusters of yellow star-like flowers on 8 to 10 inch tall stems above its blue-green leaves. A native of southern Europe, it was considered a sign of prosperity and good luck. A. moly blooms profusely, doesn’t mind a bit of shade, and naturalizes well. At less than a foot tall, it’s good for a rock garden or in beds and borders. (A. flavum is yellow, too, and taller, with bell-shape florets.)

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  • For a true blue lollypop try A. caeruleum. A Siberian native, it has 1-2 inch wide densely packed round blossoms and grows 12-18 inches tall.
  • Sweet-scented A. neapolitanum, aka the bride’s onion, bears pure-white, star-shape flowers forming loose umbels. It’s about a foot tall and needs full sun but lacks winter hardiness, becoming perennial only in Zones 7 and 8. A. roseum has much the same form, but its flower heads are pink.
  • For something a little different look for A. schubertii. It looks like a 4th of July sparkler with a huge starburst of tiny pink blossoms. It also grows 12-18 inches tall.

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  • Star of Persia (A. christophii) has a huge flower head consisting of up to 100 individual pinkish-purple flowers that can be 8 to even 10 inches across. It grows 18 to 24 inches tall.
  • Drumstick alliums (A. sphaerocephalon) are maroon-red balls of flowers on 20 to 24 inch tall stems. They grow to 2 feet tall and naturalize easily in Zones 4 to 10. Fragrant and distinctly percussive-looking, they make an interesting statement in the garden or vase.
  • Looking like a dark red Queen Anne’s lace A. atropurpureum is an eastern European native that grows 20 inches tall.
  • Commonly called ornamental garlic, A. aflatunense is one of the loveliest species. Dozens of small, star-shape flowers form a lilac-purple globe, which rises about 10 inches above narrow blue-green leaves. Native to Iran, ‘Lucy Ball’ and ‘Purple Sensation’, two aflatunense hybrids, are deep, dark purple and naturalize well in the garden.

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  • Tired of purple? ‘Mount Everest’ is a pure white allium with 4-6 inch wide flowers that look like giant snowballs. It grows 3 to 4 feet tall. ‘White Giant’ has even larger flowerheads on 3 to 4 feet tall stalks.
  • A. azureum, or blue of the heavens, is a true cornflower blue and grows up to 2 feet tall.
  • Surely the biggest is the aptly called giant onion, A. giganteum. As their Latin name says, these are the big guys. Shooting up to 6 feet tall, they have gray-green leaves and bear big, round, deep purple flowerheads 5 to 10 inches across.
  • The best allium to grow in pots is A. karataviense. Although only 8 to 10 inches tall, it has 4-inch, slightly scented blossoms. It usually flowers in pink and pale lilac shades.
  • ‘Globemaster,’ a hybrid, bears deep-violet, 6- to 8-inch, globe-shape flower heads and grows 3 to 4 feet tall.
  • ‘Gladiator’ grows to be 3 to 5 feet tall and has soft-ball sized rosy-purple flowers.
  • ‘Summer Drummer’ is the tallest hybrid at 4 to 6 feet tall. It has baseball-sized flowers with a mix of purple and white florets.

Allium Planting and Growing Tips

All are easy to grow. Fall is the best time to plant the bulbs.

  • All alliums like rich, well-drained soil and prefer a sunny site, although many species will tolerate shade.
  • Set all but the largest bulbs 4 inches deep; set the giants 8 inches deep—measured from the base of the bulb.
  • The bulbs are long-lived and multiply readily. Most will naturalize in Zones 4 to 8, and they bloom on a most timely basis, in May or June or even July, between the carnival of spring bloom and the full flowering of summer.
  • Spread alliums throughout the garden in clusters—standing alone, they tend to look odd. The best effect is gained by planting a clump of bulbs—three to five spaced well apart for large alliums or a group of 10 to 15 for smaller species.
  • If you’re looking for good companion plants, alliums look great among mounding perennials such as lady’s mantle, true geraniums, irises, or sedums. Hostas, silver-leaved artemesias, and peonies also make good companions. These will help to hide the alliums’ foliage, which tends to get brown by the time they flower.
  • Cutting advice: For indoor arrangements, cut alliums when the flower heads are just one-quarter open. Any faint oniony scent released by cutting the stems will disperse as soon as you put them into water.

When you are bulb shopping this fall consider adding a showstopping giant allium or a delicate-looking dwarf to your garden.

About This Blog

Get inspired by Robin Sweetser's backyard gardening tips. Robin has been a contributor to The Old Farmer's Almanac and the All-Seasons Garden Guide for many years. She and her partner Tom have a small greenhouse business and also sell plants, cut flowers, and vegetables at their local Farmer's Market.

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Planting Peony's

plant your peony just below the surface of soil. I no its dumb , but they will not bloom if covered more that one or two inches.
Sandy soil? Water once a week . Your dry -hot weather in Nebraska is not so good. They like sun and a lite shade in afternoon if you have hot weather.
Ants: They eat the sap the peony puts out on their flowers so leave them alone or they may not OPEN. This act of ants helps the flower to open. it will take maybe 2 or 3 years for you to get flowers when tubers are planted.
I don't feed mine anything except maybe ground up egg shells every year.
I transplant mine in early spring or plant them in early spring like mid may.

Edible?

Are any of these good edibles?

Peonies That Won't Bloom

I have had two peony plants for several years, and one of them won't bloom at all and the other one had ONE flower on it this last May. It didn't really bloom all that well either. I live in an area of Nebraska that has very sandy soil. It's just south of the Sandhills area in the mid-western area of the state.

I've been told not to plant them too deep. But when I ask how deep, all I get is a shrug and an "I don't know----just not too deep". It's really frustrating. I love these plants, but I can't seem to get them to flower. I was also told that they can't flower unless they have ants on them. Is that true? I was also told to put bone meal in with them----which I did. Still no results!

What am I doing wrong?

Thank you in advance for any suggestions/help you can give me....

Allium

I ordered these bulbs, set them out by instructions and they never came up. They sent me some more, they never came up either. What am I doing wrong here in AL?

How frustrating! Is your soil

How frustrating! Is your soil fast draining? The bulbs will rot if they have to sit in soggy soil, especially over the winter months. If you want to try a 3rd time, plant them in a raised bed, not too deep.

allium

What zone for this flower, and the latest it can be planted....thank's

They are good in zones 4-9.

They are good in zones 4-9. The smaller bulbs should be planted immediately to keep them from drying out. Like all fall planted bulbs the optimum time is when the soil temperature drops below 60 degrees. Measure it about 6 inches down using a soil thermometer. Once the soil temps drop below 40 degrees, root development stops so even though many sources say you can plant until the ground freezes it is best to get your bulbs into the ground while the soil is still in the 40’s.

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