Ornamental alliums are tall, flowering perennials that grow from bulbs. Planted in fall, these giant purple and white flower heads stand out in the early spring garden, providing vital nectar for bees and butterflies.
This is part of my Best Flowering Plants for a Cottage-Style Garden series.
Growing Alliums
Ornamental Allium | Genus: Allium
Herbaceous geophyte perennial with true bulbs
• Zones 3 to 9
• Full sun to part shade
• Same botanical genus as onions, leeks, garlic and more
- Allium Growing Guide
- Shop Online: Buy allium bulbs (US shipping)
I love alliums in spring and so do the bees! Just as the early spring tulips and daffodils are finishing up, it’s allium time.
There’s nothing quite like these tall, bold flowering plants with their giant purple or white flower heads.
As winter fades out, there are few food sources available, and the bees go wild for them, marking the transition to the warm growing season.
It is easiest to plant alliums from bulbs.
Planted in fall, they will flower in spring, and provide blooms for several years to come. This lists more spring flowering bulbs that can rebloom year after year.
The bulbs will gradually multiply, and the original bulbs will gradually weaken or die off.
At some point you may need to divide the bulbs to give the babies adequate growing space.
Allium flowers also produce seeds, which may sprout in the garden as well.
I’ve certainly found that alliums spread around my garden (which I love), but I’m not entirely sure if it was by seed or bulb, or, more specifically, from squirrels digging them up and moving them.
Frequently Asked Questions
What’s the best time to plant alliums?
The best time to plant allium bulbs is in fall after your first frost but before the ground is frozen.
Follow the directions on your bulb pack or plant at a depth 3x the size of the bulb. If the bulb is 2-inches tall, plant it 6-inches deep.
How much light do alliums need?
Alliums can grow in full or part sun. Keep in mind, that they need the light in early spring before some leaf canopies on trees have opened, so this allows more planting options.
Blooms may be slightly delayed in part sun.
Light Exposure Definitions
What soil conditions are best for alliums?
As with any bulbs, ornamental alliums need well-draining soil because they rot if waterlogged.
When do alliums bloom?
Alliums bloom in spring and the flowers last for several weeks.
Should I cut back alliums after flowering?
Alliums should not be cut back after flowering. The post-flowering stage is the time when the plant replenishes energy for the next blooming cycle. It’s best to let the flowers and stems die off naturally. When dry, seeds can be saved and flower heads can be preserved as decorations.
When can alliums be divided?
You can divide the bulbs any time the ground is workable. It’s recommended to do so before or long after flowering so you don’t disrupt the flower cycle.
Can you grow alliums from seed?
Allium seeds are slow growing—that’s why it’s more common to grow from established bulbs. It can take years from seed to flower.
If your seeds come from a cultivar in your garden, they may not grow flowers true to type but it’s always fun to see what you get.
Some species need cold stratification to germinate. This would occur naturally in a cold climate garden when they spend the winter in the ground.
In your home, you can use the stratification method shown here for delphinium seeds.
If you don’t know if they need stratification, try a germination test first to see if the seeds will sprout without this process.
Alliums naturally disperse their seeds in fall, winter, and spring. Seed packets recommend sowing after last frost in spring. Be sure to mark the location with long-lasting plant tags since growth will take several years.
Allium Plant Facts
Family: Amaryllidaceae
Genus: Allium
Common Name: Allium, Ornamental Allium
USDA Hardiness Zones: 3 to 8
Cultivars: Between 200-900, depending on how it they are categorized; the taxonomy of allium is poorly understood
Origin: Northern hemisphere, Asia, Africa, South and Central America
Type: Herbaceous geophyte perennial with true bulbs
Height: 5-150 cm (up to 60 inches: 5 feet tall)
Light: Full sun to partial shade
Soil: Well-drained soil
Flower Times: Late spring to early summer
Colors: Light to dark purple, some are reddish-purple
Fertilizer: Depends on your soil—get a soil test to learn any nutritional needs
Attracts: Bees and butterflies
Avoided by: Deer and rabbits unless food choices are limited
Propagation: Plant bulbs in fall after first frost but before ground freezes
Planting depth: 3x the height of bulb
After blooming: Allow foliage to die off naturally as it provides fuel for next year’s growth. Seed heads (old, dry flowers) look lovely in winter garden.
Divide bulbs: Before or after flowering.
Toxicity: None known. Ornamental alliums are related to edible onions. Research first.
Trivia: The word allium is Latin for garlic. Allium sativum means “cultivated garlic.” Some alliums are edible; some are strictly ornamental. The pungency of edible alliums is determined by the sulfate content of the soil: the more there is, the stronger the flavor.
Resources
Find Your Frost Dates & Hardiness Zone
Plant Hardiness Zones | 
United States | 
Canada
These are listed on seed packets and plant tags to guide your choices.
Average Frost Dates | Use this calculator at Almanac.com. Enter your city and state or province to find your first and last frost dates and number of frost-free days.
Ecoregion | Learn about local native plants, animal species, and environmental conditions to make garden choices that benefit your ecosystem.
Learn More: Understanding Frosts & Freezing For Gardeners
DIY Garden Art Alliums
This craft project is made from recycled items including old nails and a softball. Follow the tutorial to make decorative alliums for your garden.
Ebook
25 Garden Art Projects & Ideas
by Melissa J. Will
Grab the top garden art DIY projects and tips from Empress of Dirt
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