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There’s something magical about seeing a cluster of ornamental alliums in full bloom. With their oversized globe-shaped flowers perched high on tall stems, they bring a sense of whimsy, structure, and bold color to any garden. Whether you’re new to gardening or a seasoned plant lover, ornamental alliums are an easy way to make your flowerbeds feel intentional and full of life.
There are three classifications of allium: spring blooming bulbs, summer blooming perennials, and edible onion and garlic varieties. This article focuses on the first classification: spring blooming bulbs.
Why Alliums Deserve a Spot in Every Garden
Ornamental alliums (sometimes called flowering onions) have an undeniable wow-factor. Each stalk produces a round cluster of dozens (even hundreds) of tiny star-shaped florets, together forming a perfect globe of bright color perched on top of a stem. Depending on the variety, these globes can be as small as 2 inches or as large as 8 to 10 inches wide, making them a showstopper up close and from a distance.
The classic color is a royal purple, but alliums also come in white, pink, yellow, and even light blue tones. In my garden, the purple alliums always steal the show, but a cluster of white alliums can bring a fresh look that’s equally impressive.
One of the best things about ornamental alliums is how easy and reliable they are for home gardeners. These bulbs are hardy perennials (most thrive in USDA Zones 4 to 9) that come back year after year and suffer few problems.
- Deer, rabbits, and other critters leave them alone since their foliage and blooms have a slight onion-garlic scent (a huge bonus if you’re tired of animals eating your plants!).
- They’re disease and pest-resistant, so you won’t be spending lots of time babying them with special care.
- Pollinators adore them, so expect to see lots of bees, butterflies, and other beneficial insects flocking to them.
In short, alliums add bold, dramatic color and structure to the late-spring garden with such minimal effort. They bridge the gap between spring and summer, extending your garden’s bloom season in style.
Favorite Allium Varieties to Try
With over 700 species of allium available, you can find an ornamental allium for every garden size and style. To keep it simple, here are seven of my favorite tried-and-true varieties I recommend for home gardeners (including some of my personal favorites):
1. Purple Sensation
- A classic purple allium that’s often the first to bloom in late spring. It produces 4- to 5-inch round violet-purple flower balls on 24- to 30-inch tall stems.
- Blooms in May; about 2 to 3 feet tall
- Available from High Country Gardens
2. Globemaster
- The showstopper! Globemaster boasts huge globe blooms up to 8-10 inches across in a deep lavender-purple. The sturdy stems (about 2-3 feet tall) hold the blooms high, and each globe lasts for weeks. This hybrid doesn’t set seed, so all its energy goes into the flowers.
- Blooms in late spring to early summer; about 30 inches tall
- Available from Eden Brothers
3. Mount Everest
- A stunning white allium that adds contrast and elegance. Mount Everest has 5- to 6-inch white flower heads on 3+ foot stems. It blooms around the same time as Purple Sensation, making it a great pairing for a purple-and-white theme.
- Blooms in late spring; about 3-4 feet tall
- Available from Dutch Grown
4. Gladiator
- Another giant purple allium, similar to Globemaster (above) in color and form. Gladiator blooms in early summer with slightly smaller (4-6-inch) violet-purple globes on very tall stems (3-4 feet). It’s known to be a bit taller than the Globemaster and makes an impressive vertical accent.
- Blooms in early summer; up to 4 feet tall
- Available from Dutch Grown
5. Schubertii
- A unique variety for the adventurous gardener. Instead of a tight globe, this one looks like a firework blast – a 10- to 12-inch spidery sphere of rose-purple florets with long tails. It’s shorter (about 12-18 inches tall), but the dried seed heads can be saved for arrangements.
- Blooms in late spring; about 1 to 1.5 feet tall
6. Drumstick Allium
- A later-blooming allium with a completely different look. Drumstick alliums have little egg-shaped flower heads that start green and mature to wine-purple. They’re smaller (1- to 2-inch oval heads on 2-foot stems), but you plant them in clusters for a bigger effect. They bloom in midsummer (June to July), extending the allium show into the hotter months.
- Blooms in early to midsummer; about 2 feet tall
- Available from Holland Bulb Farms
7. Karataviense
- A short and compact allium with broad, gray-green leaves and soft pink to lilac globe blooms that sit close to the foliage. It’s perfect for the front of flowerbeds or containers.
- Blooms in mid-spring; about 8–12 inches tall
- Available from John Scheepers
Tip: Plant allium bulbs in groups of three, five, or more for the best visual impact. A solitary allium is fun, but a cluster creates a real wow moment.
When and How to Plant Allium Bulbs
Planting time: Like most spring-blooming bulbs, ornamental alliums are typically planted in the fall (super important to know this!). I usually plant mine in the ground after the first fall-time chill, when soil temperatures drop to about 60°F or cooler. In many areas, this means October or November (earlier in the northern part of the US, a bit later in the southern part). Fall planting gives the bulbs a chance to establish roots before winter.
Planting bulbs has become one of my favorite fall rituals. The air is a bit crisp, the soil is still workable, and there’s something peaceful about knowing you’re already getting ready for spring. I always think of it as a quiet investment since you forget about them for months, and then they’re ready in spring with no additional thought!
If you missed fall planting, you can sometimes find potted alliums in spring garden centers, but bulbs you plant in the fall tend to perform the best.
Location and soil: Alliums will rot in soil that stays perpetually wet, so good drainage is a must! Choose a spot in your flowerbed that doesn’t stay waterlogged: any well-draining site works well. If you have heavier clay soil, add a little compost or sand to the planting holes to improve drainage (these bulbs hate wet feet).
Alliums also prefer full sun for best flowering. They’ll tolerate partial shade, but you typically get taller stems and larger blooms with at least 6+ hours of sun. A spot with morning sun and a bit of afternoon shade is fine, especially in hotter climates. Soil fertility isn’t a huge concern (average garden soil is fine), but you can mix in some bulb fertilizer or bone meal at planting time for an extra boost.
How to plant: Plant the bulbs at a depth roughly 3 times the height of the bulb (usually 4 to 8 inches deep, depending on the bulb size). Place the bulb pointy side up (root side down) in the hole. Space them about 6 to 8 inches apart for the larger alliums, or a bit closer together for smaller bulbs. I often cluster three bulbs in one wide hole rather than digging separate holes. It’s quicker, and they’ll sprout in a nice clump. After planting, water them well once to help settle the soil. Once that’s done, you can pretty much forget about them!
The bulbs will quietly spend winter underground, and you’ll get a wonderful surprise in late spring when the shoots emerge.
Container planting: You can grow alliums in pots, too! Just use a deep container with excellent drainage. Plant bulbs at the same depth as in the ground, pack them in somewhat close for a full look, and overwinter the pot in a cool, sheltered spot if your winters are very harsh.
It is best for the bulbs to stay in soil that maintains a temperature of 35°F to 40°F. If the soil temperature dips below 32°F, it could freeze the bulbs and cause them to rot.
In spring, bring the pot into the sun and enjoy the show.
Allium Care and Maintenance
One reason I recommend alliums to every gardener is that they’re remarkably low-maintenance. Once you’ve planted the bulbs, they really don’t ask for much. Here are some practical care tips from my experience:
- Watering: In spring, alliums typically get by on regular rainfall. They prefer dry to medium moisture and are even quite drought-tolerant once established. I rarely need to irrigate mine. Overwatering can lead to bulb rot, so when in doubt, err on the dry side. After blooming, as the plants go dormant in summer, stop watering altogether as the bulbs like a dry rest.
- Feeding: Alliums don’t usually require heavy feeding. When planting in fall, you can toss a little bulb fertilizer or bone meal into the hole. They’ll generally bloom fine in the spring without extra feeding if your soil has decent organic matter.
- Foliage care: One quirk of alliums is that their leaves often start yellowing or dying back just as the flowers are blooming. Don’t worry, as this is normal. The leaves appear in early spring, nourish the bulb, and then tend to look worn by bloom time. Resist the urge to cut the leaves early. Just let them yellow and wither naturally, because they’re still feeding the bulb for next year. Once they’re truly yellowed or dried up (usually a few weeks after flowering), you can gently remove or trim them away.
- Deadheading: After the allium flowers finish, you have two choices: 1) You can deadhead (cut off the spent flower heads) if you want the plant to direct energy back to the bulb. This also prevents any unwanted self-seeding in varieties that set seed (many alliums don’t self-seed aggressively). 2) You can leave the seed heads on. They dry into ornamental globes that look lovely in the garden (and in dried arrangements).
- Dividing bulbs: Allium bulbs will naturalize slowly, forming offsets over the years. You might notice clumps getting crowded or flowering less after many years. If that happens, you can dig up and divide the bulbs in late summer or fall, after the foliage has died back. Just separate the smaller bulbs and replant them elsewhere. Honestly, in my garden, this is rarely needed since alliums tend to thrive without much attention.
Aside from these basics, there’s not much else to do. Just remember where you planted them so you don’t accidentally dig them up. Then enjoy the surprise each spring when the shoots pop up!
Bloom Time and Seasonal Highlights
One reason I love alliums is how they fit perfectly into the garden calendar. Most ornamental alliums bloom in that sweet spot of late spring to early summer, right as the tulips and daffodils are wrapping up and before the summer perennials hit full swing, acting as a bridge between spring and summer. In my Zone 5b garden, for example, Purple Sensation alliums open in mid-to-late May, just after the last tulips. Then varieties like Globemaster and Gladiator take the stage in late May and early June, around the same time the irises and peonies are blooming.
Different allium varieties have different schedules, which you can use to extend their appearance in your garden:
- Mid-May: Early types (like ‘Purple Sensation’)
- Late May to early June: Giants like ‘Globemaster’ and ‘Mount Everest’
- June and July: Drumstick alliums
- August: Allium ‘Millenium,’ ‘Summer Beauty,’ and other summer-blooming varieties (Note: These varieties are summer-blooming perennials, not a fall bulb.)
The idea is to create a succession of blooms, and by planting a mix of early, mid, and late-season types, you can enjoy weeks of color. Each globe typically looks full for several weeks, and even as the color fades, the form remains. I often leave the dried seed heads standing through July because they continue to add interest. Alternatively, you pick the seed heads and use them in craft projects or unique floral arrangements.
Design Ideas: Companion Planting with Alliums
I love mixing allium into perennial beds and border plantings. Here are some of my favorite combos:
- Peonies – Their big blooms and dense foliage complement the tall orbs of alliums.
- Catmint (Nepeta) – The purple-blue haze beneath adds softness and contrast.
- Salvia or Russian sage – Their spiky blooms balance the round allium heads.
- Lady’s mantle (Alchemilla) – Its chartreuse blooms and ruffled leaves play off the purple.
- Ornamental grasses – For a naturalistic, airy look.
A few other tips to think about with alliums:
Hide the foliage: Allium leaves can look messy as they die back. The trick is to plant allium bulbs among other foliage plants so the dying leaves are hidden.
- For tall alliums, I plant them in the middle or back of the flowerbed, allowing neighboring perennials to camouflage the leaves.
- Smaller alliums can go in front of or among low-growing perennials like catmint (Nepeta), lamb’s ear, or salvia. These surrounding plants conceal the base of the allium.
Groupings for impact: More is more with alliums. Rather than a single stem here or there, plant them in clusters or repeating groups. For instance, a sweep of 5 to 7 (or more!) Globemaster alliums in a row can form a really beautiful focal point. Don’t be afraid to mix different allium varieties together. Purple and white alliums combined make each other stand out (one of my favorite combos is Purple Sensation with Mount Everest, which bloom together and are similar height).
Use them as cut flowers: I sometimes snip a few for an indoor vase. They last long and add a sculptural element to arrangements. But it can be hard to take them out of their natural element, as they look beautiful during the spring.
Conclusion
Ornamental alliums are easy, dramatic, and rewarding. They add bold color, architectural interest, and attract pollinators to any flowerbed, all while keeping deer and rabbits away.
Plant a few this fall, and by next spring, you’ll be greeted with those charming globes of purple, white, or pink bobbing in the breeze.
Whether it’s people visiting my yard or followers on social media, I always get the question, “What are those gorgeous round flowers?” So get ready for people to love them in your own yard!
Happy gardening!
