Allium is a genus of ornamental flowering bulbs that includes over 700 species, including the popular garden varieties commonly known as ornamental onions With their unique, spherical flower heads topping slender stems, alliums add fabulous visual interest to gardens But one key question many gardeners have is – just how long is that eye-catching display of color really going to last?
Understanding allium bloom times helps with planning, planting, and getting the most out of these ornamental bulbs. In this complete guide, we’ll demystify everything you need to know about how long allium flowers last
An Overview of Allium Plants
Before diving into details on bloom times, let’s do a quick overview of what makes alliums so special:
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Alliums belong to the same plant family as edible onions, garlic, chives and leeks. There are over 700 different allium species.
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They grow from bulbs, multiplying year after year when happy in their growing conditions.
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The flowers consist of densely packed, star-shaped florets. The inflorescence is a globe or umbrella-shaped cluster.
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Heights range from only 4 inches up to 4-5 feet tall depending on variety.
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Popular allium flower colors include shades of purple, pink, white, yellow and blue.
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Alliums thrive with full sun exposure. Well-drained soil is a must.
Now that you’re familiar with the basics, let’s explore how long those fabulous flowers last.
Allium Bloom Times by Species
There is some variability in bloom times, but in general:
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Large, ornamental alliums tend to bloom for 2-3 weeks.
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Smaller allium species may only bloom for 1-2 weeks.
Here are typical bloom times for some popular allium species:
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Allium giganteum: Late spring, 2-3 weeks
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Allium ‘Gladiator’: Early summer, 2-3 weeks
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Allium christophii: Early summer, 2-3 weeks
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Allium ‘Millenium’: Early summer, 2-3 weeks
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Allium tuberosum: Early summer, 1-2 weeks
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Allium caeruleum: Spring, 1-2 weeks
Larger allium varieties give you the most days of color and enjoyment.
Extending Allium Bloom Times
You can stretch out allium blooms even longer through smart planting and care practices:
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Plant early, mid and late-blooming varieties together for months of continuous flowers.
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Stagger plantings over several weeks to have blooms coming on in succession.
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Provide consistent moisture once buds start swelling for best development.
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Deadhead spent flowers as they fade to encourage reblooming.
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Plant bulbs in groups for greater visual impact.
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Choose sheltered garden sites protected from heavy winds and rain.
Follow these tips and you can enjoy alliums for up to 6-8 weeks!
Post-Bloom Care for Alliums
Once the floral show is over, proper ongoing care ensures plants will remain vigorous:
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Allow foliage to die back completely before removing. This takes 4-6 weeks usually.
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Stop watering and let bulbs go dormant through summer.
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Cut back dead foliage once it turns yellow or becomes unsightly.
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Divide congested clumps every 3-4 years in fall after foliage dies back.
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Fertilize bulbs with balanced fertilizer when planting and as foliage appears each spring.
Caring for alliums after blooming keeps them thriving year after year.
Matching Allium Varieties to Bloom Seasons
One of the best ways to maximize allium blooms over time is to select varieties from each season:
Spring Bloomers:
- Allium moly
- Allium caeruleum
- Allium karataviense
- Allium nutans
Early Summer Bloomers:
- Allium ‘Millenium’
- Allium ‘Gladiator’
- Allium ‘Globemaster’
- Allium christophii
- Allium tuberosum
Midsummer Bloomers:
- Allium giganteum
- Allium ‘Purple Sensation’
- Allium atropurpureum
- Allium schubertii
- Allium ‘Pinball Wizard’
With strategic choices, you can realistically have alliums blooming for 3-4 months!
Frequently Asked Questions
Here are answers to some other common questions about allium blooms:
How long do cut alliums last in a vase?
Cut allium stems will generally last 10-14 days if properly conditioned and cared for.
Why did my allium only bloom briefly?
Insufficient sunlight, overcrowding, overwatering, or damage from heavy winds/rain can shorten bloom times.
Should spent allium flowers be deadheaded?
Yes, deadheading faded blooms helps neaten appearance and encourages more reblooming.
Can I cut alliums to enjoy as indoor flowers?
Absolutely! Alliums make stunning cut flowers. Just be sure to leave the foliage intact in the garden.
When should I remove allium foliage after blooming?
Never remove foliage until it completely dies back, so bulbs can fully recharge for next year’s growth.
Conclusion
With their unique, spherical flower heads atop slender stems, alliums add fabulous visual interest to gardens. By understanding their bloom times, which are typically 2-3 weeks, you can plan rotations and stagger plantings for months of continuous color. Proper planting, care and deadheading keeps alliums flowering longer. Matching early, mid and late varieties extends the season of enjoyment. Now you have all the insights you need to maximize the floral display from these fabulous bulbs!
Deer resistant and dynamic, these bulbs provide color from the first showers of spring to the last leaves of fall
Alliums are often overlooked as one of the best bulbs for constant color throughout the seasons. Part of the problem is their common name: ornamental onion, which conjures up s of supermarket onions in shades of lime green or red. Alliums actually come in oval, spherical, or globular flower shapes, blooming in magnificent colors atop tall stems.
Because good perennial-garden designs are often made up of contrasting shapes, alliums’ rounded blooms make them great components for interesting garden combinations (not to mention that deer generally avoid them—to escape onion breath). Pair them with spikes or other large-leaved perennials to hide any decaying foliage.
It’s easy to think of alliums simply as colorful summer plants, but these easy-to-grow bulbs have options that will keep the blooms coming right up to the first frost. You’ll find outstanding choices here that will make you reconsider alliums as your new seasonal companions.
Hardiness: Alliums can be grown in Zones 3 to 9, depending upon the species and cultivar.
Alliums aren’t too picky: In most cases, alliums grow in average garden soil and need full sun and good drainage. The drainage is critical because so many of the bulbs are huge and will rot with too much moisture.
Aside from that, they are easy to grow and come back year after year with almost no maintenance. Occasionally, they need dividing after a few years, when you start to notice a decrease in flower production (usually this pertains to those with small bulbs). One of the best things about alliums is that most animals, especially deer, find the taste unappealing and won’t nibble on the leaves.
Plant them in fall: Alliums go in while leaves are falling. Average planting depth should be about three times the diameter of the bulb. I have planted alliums late in fall right up to Thanksgiving. Just be sure the ground hasn’t frozen yet so that the bulbs have time to take root.
Spring is for more than just daffodils and tulips
In late spring, ‘Jeannine’ golden onion (USDA Hardiness Zones 3–9) emerges, growing a scant foot tall. It has two stems of individual, star-shaped, golden yellow flowers forming a circular floret. I love ‘Jeannine’ for the ease with which its soft, straplike, blue-green leaves tuck between the wonderful blue flowers of late spring to early summer. To get any kind of display, plant at least a dozen bulbs. ‘Jeannine’ multiplies continuously and, in a few years, will put on quite a show. If you love large drifts of golden daffodils, you will be equally impressed with this small golden treasure.
After viewing this average-size garden gem, moving on to something that looks like a giant lollipop on a stick is a shocker. Giant onion (Zones 5–9) is all that its name implies, peeking out in late spring and growing up tall and bold. The 4-inch-diameter flower is a pretty shade of lilac, but the large leaves are troublesome, turning yellow even before full flowering is complete. If this plant is not placed in the back of a border, it will need a hardy perennial to cover its dying foliage. Giant onion’s flowers are long blooming and are excellent to use as cut flowers. When planting, leave plenty of room for these large bulbs to grow.
In late spring, the short, squat Turkestan onion (Zones 5–9) flowers. This is my kind of plant, standing a mere 1 foot tall. The thick leaves on this onion are a showy gray-green mottled with shades of purple and a sort of reddish edge. The long-blooming flower is a pale silver-lavender. Even after flowering, do not remove the spent flower because it dries well. During a previous year, I spray-painted one to make a fairy wand for my daughter’s Halloween costume. For those who dare to be different, try spray painting them in your garden; it creates a funky effect. Plant Turkestan onion in groups of three or five for maximum impact. It looks great with ‘Caradonna’ blue sage (Salvia nemorosa ‘Caradonna’, Zones 5–9) in the background—a dramatic combo.
A handsome plant that has been grown since Victorian times is tumbleweed onion (Zones 4–9). The flowers are rose purple and begin to form on short stems. The infertile flowers shoot out, giving the effect of fireworks. Tumbleweed onion has an open, airy look rather than a compact head. The leaves go fast after flowering, but the seed head will look good for a while. It will eventually drop off and begin to roll around the garden, just like a tumbleweed in the Old West.
