I’m an equal opportunity plant lover, but there’s something extra appealing about a plant that offers a ton of visual impact without requiring a ton of work.
USDA Hardiness Zone 3.
As if that’s not enough to recommend them, they aren’t attractive to voles, deer, and rabbits. Being part of the garlic family, they resist a lot of the common pests and diseases that may plague other flowers as well.
In spite of all these attractive features, I’d plant them even if they fussy and positively irresistible to animals. That’s because quite frankly, they’re showstoppers.
From the massive five-foot-tall ‘Gladiator’ to the petite and lacy ‘Blue Allium,’ they all stand out like little floral fireworks in the garden.
The leaves, stalks, and flowers have a geometric look that contrasts with the more billowy, nebulous shapes that commonly fill the garden.
In fact, that’s why I’d say these plants aren’t for the shy gardener. A few of these and you’ll have the neighbors stopping by to praise your captivating display.
Interested in adding some flowering alliums to your garden? Here’s what I’ll cover:
Although they aren’t high maintenance, they do have some specific requirements. Let’s jump in.
What Are Flowering Alliums?
If you’ve ever seen the flower of a chive plant, it’s basically a lot like that, but groomed over the ages into different shapes, sizes, and colors.
in our growing guide.
Some varieties can have a tendency to be spreaders. This is usually not a problem in cooler climates, but , commonly known as “blue garlic” can spread and take over the garden in warmer locations.
For example, Naples garlic, is currently listed on California’s list of noxious weeds.
Fortunately, there are many sterile or semi-sterile hybrid cultivars available, such as ‘Millenium.’
You can learn more about how to control flowering alliums in this guide. (coming soon!)
If you are in doubt, you can contact your local extension office to find out which species can cause problems in your area.
Cultivation and History
Alliums are native to parts of Europe, northern Africa, and western and central Asia.
There also are over 100 species native to North America, including , (American prairie onion), and , and only one found in the Southern Hemisphere, , native to South Africa.
except tropical regions and Australia.
According to R. Kamenestky and R. M Fritsch from the Department of Ornamental Horticulture at the Volcani Center in Israel, ornamental alliums weren’t commonly cultivated until the late 1800s when botanists in Europe and Russia introduced species from central and southwest Asia to European botanical gardens.
All alliums, ornamental or not, can be propagated from seed, bulbs, or by division. Starting from seed requires patience, as they typically won’t bloom for at least a year or two, if not more in some cases.
conduct a soil test to determine if you need to work any amendments into the soil.
Ornamental alliums don’t demand much beyond well-draining soil, but if your earth is seriously depleted in any of the big three nutrients – nitrogen (N), phosphorus (P), or potassium (K) – you’ll want to amend it.
You can purchase seeds or plant some that you saved from the previous season (more on that below). When it’s time to put them in the ground, loosen up the soil. It’s best to plant seeds after the last frost has passed in your area.
In the spring, after all risk of frost has passed, sprinkle the seeds over the area where you want your plants to grow. The seeds are small, so don’t bother sticking them in one by one. Just broadcast them liberally around the growing area.
Cover the seeds with 1/4 inch of soil and water well using the soaker attachment on your hose so you don’t disturb them. Keep the soil moist until you see the first green sprouts pop up. Then you can reduce watering to allow the top inch of soil to dry out slightly in between.
Thin the plants to the recommended distance for spacing described on the seed packet once they emerge. Alliums come in a variety of sizes and have different space requirements.
Dividing your allium plants is a fall chore. Every three to four years, it’s a good idea to divide your plants to keep them healthy and ensure that they are well-spaced.
The first step is to cut back the flower heads and any foliage that remains at the end of the growing season four to six weeks before the first frost.
Dig down nine inches, allowing a six inch margin around each plant. Alliums don’t have deep roots, but you want to avoid disturbing them too much.
Keep in mind, as mentioned, alliums can either grow from bulbs or rhizomes, but the process for digging them up and dividing them is similar.
Using your shovel, lift up the clump of dirt and gently tease out the bulbs or rhizomes.
Separate the bulbs and place one of them back where it was growing, at the same depth that it was planted to before you dug it up. Work in a little bulb fertilizer along with the soil if you haven’t fertilized your plants in several years.
To divide rhizomes, slice the rhizome in half using a sharp knife. Put one half of the rhizome back in place at the same depth it was growing.
Next spring, your plant will return.
Take the excess bulbs and plant them as you would new bulbs or transplants, which we cover in the next section.
If you can’t plant right away, store the bulbs in a cool, dark spot for a few months. Rhizomes can be stored in a plastic bag in the fridge for a week or so.
Planting Bulbs or Rhizomes
Whether you buy bulbs at a local retailer, online, or obtain some from a friend or through division, the planting process is all the same.
available at Amazon, if desired.
This fertilizer is specifically formulated not to burn the bulbs of the plants.
You want to place bulbs with the pointy ends facing up about three times as deep as the bulb is long – typically four to eight inches. If you’re planting rhizomes, you should follow the grower’s recommendations for depth and make sure the shoots are facing up.
Space them according to the specific recommendations for your selected species or cultivar. This typically ranges from four to 12 inches. Cover with soil and water well.
How to Grow
Most alliums like lots and lots of sun, at least six hours of direct sunlight a day. However, some species do better with a bit of shade, particularly in the heat of the afternoon. All varieties will tolerate partial sun.
- Plant in full sun or part shade, depending on the variety
- Allow the soil to dry out slightly between waterings. Flowering alliums can handle a short period of drought.
- Provide support for tall varieties or those with large seed heads.
The foliage of bulb alliums dies back just before the plant blossoms. When this happens, you can snip away the dead leaves to improve air circulation and tidy up the garden.
Rhizomatous alliums typically retain their foliage until the fall. After it has died back, you can cut the dead foliage down to the ground.
Species and Cultivars to Select
Since alliums flower at different times, consider planting some early, mid-season, and late blooming types so you can enjoy their vibrant blooms in your garden all season long.
Here are some standout varieties:
‘Blue Onion’ () differs from the common purple blossoms that you might be familiar with, with striking loose clusters of vivid blue flowers. It grows to be a little over a foot tall and blossoms in the early spring.
This type prefers a bit of shade.
You can find bulbs for your garden available at Eden Brothers.
If you ever played an imaginary drum set when you were a kid, then Drumstick alliums () are sure to delight. They’re shaped like those mallets that drummers use on cymbals and toms.
The floral heads start out green and gradually transition to reddish-purple.
Plants grow to about 18 inches tall. Grouped in a cluster, they make a statement in the garden that is hard to match.
They’re some of the later types to bloom, starting in early summer.
Find bulbs for this striking garden addition from Eden Brothers.
If you really want to ramp up the wow factor in your garden, ‘Globemaster’ is pretty hard to top. It’s a hybrid cross between and .
If you’ve ever witnessed a garden full of the massive purple pincushions swaying together in the breeze, it’s a sight you won’t forget.
Because they’re so large, you can use them as a focal point, planted with a variety of other low-growing plants. This helps to hide the “bare ankles” after the foliage dies back, as well.
They have sterile seeds, so they won’t spread on their own. But they’re worth the investment and you can divide the bulbs every few years for more plants.
The majestic seven to eight-inch purple heads grow on three to four-feet stalks and stick around from early spring to midsummer. They have an intense, sweet scent.
You can find bulbs available from Eden Brothers.
With bright yellow blooms, ‘Moly’ tops out at about a foot tall. A late-flowering variety, it will continue to provide color well into the fall.
You can find bulbs to plant in your garden available at Burpee.
This massive cultivar () grows up to four feet tall with snowy white flower heads that are an impressive three inches wide, and resemble a beautiful ball of lace standing above the other plants in your garden.
You can find bulbs available at Eden Brothers.
‘Pinball Wizard,’ a hybrid of and is aptly named. The blossoms on this plant look like magical clusters of tiny purple pinwheels.
It’s similar to ‘Globemaster’ in size, color, scent, and bloom time.
This cultivar produces sterile seed.
You can find packages of bulbs available from Eden Brothers.
All alliums are relatively undemanding in the garden, but ‘Purple Sensation’ () is even more so.
Give it full sun and well-drained soil, and you won’t have to think about it much again except to enjoy the lovely purple blossoms.
If flowers May through June on three-foot stalks.
You can find bulbs available at Eden Brothers.
‘Schubertii’ is a standout thanks to the arrangement of the petals that burst out and away from the center to resemble an explosive sparkler. This species is not reliably cold hardy.
It grows to about 20 inches tall and doesn’t mind a little shade.
Make this species a part of your garden or cut-flower displays by grabbing some bulbs from Eden Brothers.
Managing Pests and Disease
Flowering alliums are fantastic in that instead of needing to worry about battling pests and disease all year long, you can sit back in your hammock and enjoy the display.
the only confirmed areas that have this pest are New England, Pennsylvania, and Maryland.
The allium leafminer () is an awful pest for people growing edible alliums. For the ornamental grower, they mostly cause surface damage.
Leafminers are the larvae of flies that have clear wings and yellow heads. The adults lay their eggs in the spring and fall. Once they hatch, the white or cream-colored larvae start chewing winding tunnels through your lovely allium leaves.
An infestation of enough of these little nibblers can stunt plant growth or cause the foliage to become curled or twisted. The good news is that the leaves of many ornamental alliums naturally die back just before the plant blossoms.
That means that unless your plant is severely damaged, with extensive tunneling in each leaf, the problem will go away on its own and your plants will still provide you with showy blossoms.
You still want to control these pests if you spot them because they create conditions that invite fungi to attack your plant. Plus, if you don’t try to stop them, it’s likely they’ll return in even larger numbers next year.
If you do find that these are a problem in your garden, you can put down silver reflective mulch in the spring. Then, place yellow sticky traps six inches above the ground and within a foot or two of your plants. These traps will help capture the adult flies as they buzz around.
In addition to, or instead of sticky traps, you can also make your own water trap to catch the adults.
To do this, put a few drops of dish soap in a cup of water and place it in a shallow bowl. Place the bowl near the base of your plants. The flies will land on the water and drown. Change the water every few days.
If all this fails, a spinosad-based insecticide is a good option. Monterey Garden Insect spray, available at Arbico Organics, can be sprayed on foliage as a biological control, according to package instructions.
Onion thrips () are tiny insects that are one and a half millimeters long, with two sets of wings. You probably won’t be able to get close enough to see, but the clear wings are covered in long hair.
Predator mites, pirate bugs, and lacewings make quick work of the adults and nymphs.
BotaniGard is a fungal insecticide, available via Amazon, that you mix with water and apply to plants. Note that it reacts to UV light, so it needs to be applied in the evening or on a cloudy day.