Most gardeners don’t realize that alliums are one of the best bulbs for providing year-round color. The term “ornamental onion” conjures up images of supermarket onions in lime green or red, which is part of the problem. Oval, spherical, or globular-shaped allium flowers bloom on long stems in a rainbow of colors.
Alliums’ rounded blooms make them ideal components for interesting perennial-garden combinations (not to mention that deer generally avoid them—to avoid onion breath). To hide any decaying foliage, plant them amongst spikes or other large-leaved perennials.
The easy-to-grow bulbs commonly associated with colorful summer blooms, alliums actually have varieties whose blooms can last well into the first frost. You’ll find a wide variety of alliums here that will inspire you to rethink them as a seasonal staple.
CVS and various types of alliums are common culinary ingredients.
Hardiness: Zones 3 to 9 are suitable for growing various species and cultivars of alliums.
Alliums aren’t fussy: They can thrive in a wide range of soils and conditions, but they prefer full sun and good drainage. Many of the bulbs are enormous and will rot if there is too much water in the soil.
In addition, they are easy to grow and return year after year, requiring little or no effort. After a few years, you may notice a decrease in flower production and need to divide the plants (usually this pertains to those with small bulbs). Alliums are great because most animals, especially deer, don’t like the taste and won’t eat the foliage.
In the fall, plant them: While the leaves are falling, alliums are planted. The bulb’s diameter, multiplied by three, is the recommended planting depth. Late in the fall, I’ve been planting alliums right up until Thanksgiving. The bulbs must have time to take root before the ground freezes.
More than just daffodils and tulips bloom in the springtime.
‘Jeannine’ golden onion (USDA Hardiness Zones 3–9) emerges in late spring and grows a little over a foot tall. Star-shaped, golden yellow flowers form a circular floret on two stems. Because of the ease with which its soft, straplike, blue-green leaves tuck in between the wonderful blue flowers in the late spring to early summer, I adore ‘Jeannine.’ ” Plant at least a dozen bulbs if you want to see anything. A few years from now, ‘Jeannine’ will put on a spectacular show. Small golden daffodils are just as beautiful as large swaths of golden daffodils.
When you see something that looks like a lollipop on a stick in the middle of a garden, it’s a shock. The giant onion (Zones 5–9), which appears in the late spring and grows tall and brash, is exactly what its name implies. A lovely lilac color fills the 4-inch flower, but the large leaves, which turn yellow even before the plant has finished flowering, are a nuisance. This plant’s dying foliage will need to be covered by a hardy perennial if it is not placed at the back of the border. The flowers of the giant onion have a long blooming period, making them ideal for use as cut flowers. Make sure to give these large bulbs plenty of room to grow when planting.
Turkestan onions (Zones 5–9), which are short and squat, bloom in late spring. This is exactly the kind of plant I’m looking for, with a height of just one foot. There is a distinct reddish edge to the onion’s large, mottled gray-green leaves. The flower’s color is a delicate silver-lavender. When the flowers have faded, do not remove them as they can be used for drying. Before, I used one to make a fairy wand for my daughter’s Halloween costume by spray-painting it. If you’re looking for a unique way to decorate your garden, try spray painting some of your plants. Plant three or five Turkestan onions together for maximum impact. When combined with Salvia ‘Caradonna’ (Zone 5–9), the blue sage variety, it makes for a striking backdrop.
Tumbleweed onion (Zones 4–9) is a handsome plant that has been grown since Victorian times. Short stems of rose-purple flowers begin to emerge. It appears as if fireworks are being set off by the infertile flowers. Instead of a compact head, tumbleweed onion has an open appearance. After flowering, the leaves will drop quickly, but the seed head will remain attractive for some time. Like a tumbleweed in the Wild West, it will eventually fall to the ground and begin to roll around the garden as it does so.
Summer rolls on thanks to water-wise bulbs.
Alliums that flower in the summer has a wide range of colors and shapes. There are nodding onions (Zones 4–8) native to the Northeast. Its common name comes from the fact that its flowers hang down. Flowering begins in early summer and continues for a long time. Because it’s only 18 inches tall, this allium can easily be tucked between perennials that bloom in the spring and summer. If you’ve never grown this bulb before, you should know that it always nods when you approach it. This does not imply that it requires water.
In perennial borders, blue is a popular choice. Dark and light blues blend beautifully in the Blue Globe Onion (Zones 4–10) variety. The sphere-shaped flowers can grow up to 24 inches tall and are ideal for cutting. Use this variety in combination with the white-flowered Leucanthemum ‘Becky’ Shasta daisy (Zones 5–8) or the silver-moon Stokes aster (Stokesia laevis ‘Silver Moon,’ Zones 5–9) for a striking contrast. Sprinkler systems should be avoided because this bulb thrives in dry, hot conditions.
One of the most stunning alliums is the stars of Persia (Zones 5–8). With a 10-inch diameter light amethyst globe, silver shading, and green eyes, it’s a stunning piece of jewelry. To get the most out of this bulb, you’ll need a lot of room. The downy onion’s other common name comes from the white hairs that cover the leaves. Dried flowers are great, but don’t put them in the front of your garden unless you’re into the look of decaying foliage. Make sure it’s tucked away behind a plant that’s at least 10 inches tall.
Colorful oddballs are a great way to end the growing season.
Black onion (Zones 5–8) is one of my favorites for the summer. White star-shaped flowers have black or dark green centers, creating a striking contrast. White flowers aren’t everyone’s cup of tea due to their proneness to being washed out, but this allium’s dark centers make it appealing to gardeners of all stripes. There are a few weeks of blooming, but the seed heads still look good for a while afterward (for those of you nondeadheading enthusiasts). Incorporate some of the chocolate-colored heucheras or any other dark-leaved plant into the mix for a subtle color echoing.
Zones 4–9 are ideal for drumstick allium, which I assume refers to a chicken-related drumstick, rather than a musical instrument. This egg-shaped flower is one of my favorite perennials in my yard. In contrast to other full-sun flowers that fade, this beauty retains its vibrant hues for longer. Intricately arranged crimson-purple blooms. When golden daisies bloom in midsummer, you have an easy, no-fail combination. My favorite thing about this plant is that it blooms for three to four weeks, but the foliage begins to turn yellow before the flowers are finished blooming.
For the uninitiated, ‘Hair’ allium (Zones 4–8) appears to be growing out of an electrical outlet. Tentacle-like green flowers grow from a purple base on each stem. To get the most out of this bulb, try pairing it with something that you think is a little dull (even if you are not partial to such a weird plant).
This is a really cool plant that can grow in Zones 4–9. Because of its blue-green leaves, the plant is known as a corkscrew. Compared to its species, the circle onion’s flower is a darker shade of pink, making it more desirable. For the most dramatic effect, use it in a Japanese-inspired garden, such as a rock garden or along the front of the border.
Alliums are a favorite fall flower, and it’s easy to see why. This Japanese onion (Zones 4–9) begins blooming in September when most plants are preparing to go dormant (but it sometimes goes to frost in my cold Zone 6). The shiny, narrow foliage never looks bad because it blooms so late, which is a blessing. The purple flowers, which resemble stars, give the impression that the plant is much larger than it actually is. The white asters and mums that are in season at this time of year can be paired with it.
If this article hasn’t convinced you to become a “alliophile,” I’ll remind you: If you want to keep deer away from your garden, this is the bulb for you. Your garden will be lovely and free of deer for the duration of the year.
Taking care of Alliums
Large, softball-sized purple flowers can be found on allium plants. The flowers will last longer if they are planted in an area that is both sunny and protected from the wind. They bloom in early summer under these conditions, and the blooming period lasts for about three weeks.
Deadheading the blooms is an option after the flowers have faded. Leaving the foliage in place will give the bulbs time to gather energy for next season’s growth as the leaves fade naturally. In order to hide the allium’s straggly leaves, plant them in a bed with later-blooming flowers, such as daffodils.
After-Bloom Care for Alliums
After-bloom care for alliums is a breeze. Simply water the plants until they turn yellow and shrivel, and then stop. The plants can be cut to the ground, left in place, or divided at this point.
Splitting allium bulbs every three to four years is recommended. Lift the bulbs out of the ground by digging around the plant with a trowel. You should be able to separate the bulbs with your hands from the rest of the collection. A few can be replanted in the same spot, and the rest can be planted in new locations right away.
The care of allium bulbs that you don’t want to divide is even simpler to accomplish. It’s as simple as trimming the foliage as it ages, and then apply 2 to 3 inches (5-7.5 cm) of mulch in the fall. During the spring, remove the mulch to allow for new growth.
