Onions are often associated with cooking, but did you know they also have a floral side? Ornamental alliums, in particular, are a treat for the eyes and easy to cultivate. Whether you’re a seasoned gardener or just starting out, these plants can bring an added dimension to your outdoor space. Not only do they produce striking flowers that add visual interest, but their seed heads also provide a unique architectural element once the blooms have faded.
If you’ve had success growing chives, you’ll likely find ornamental alliums just as easy to care for. Are you ready to give it a try?
The Best Species and Cultivars
The allium family encompasses onions, shallots, and garlic, but did you know that there are over 200 species suitable for cultivation? In fact, scientists estimate that as many as 700 allium species exist! When it comes to selecting the perfect ornamental alliums for your garden, consider a few key factors. Think about the size of flowers you desire, the color palette you’re aiming for, and how much space you have available.
You’ll also want to consider the blooming period, as well as which plants will provide a beautiful contrast to your alliums. Armed with this information, you can begin your search. To make things more manageable, here are some top-notch ornamental alliums that thrive in gardens:
Blue Onion
The alluring Allium caeruleum boasts stunning, globe-shaped blooms featuring intricate star patterns, standing tall at an impressive 16 inches. This show-stopping variety thrives in a range of conditions, effortlessly adapting to USDA Hardiness Zones 2-10, its native habitat in central Asia.
Drumstick
The drumstick allium (A. sphaerocephalon) bears a striking resemblance to the mallets used by drummers, featuring vibrant purple-red heads atop a lush green base, all situated on an impressive 18-inch stem. This unique perennial is well-suited for zones 4-9, making it an ideal addition to many gardens.
Gladiator
‘Gladiator’, standing at an impressive four feet tall with striking purple blooms, is a true showstopper in the garden. This robust perennial has earned the prestigious Royal Horticultural Society Award of Garden Merit, and its durability only adds to its appeal. Not only does it thrive in dry conditions, but it also spreads readily on its own, making it an excellent choice for naturalizing. The ‘Gladiator’ is a unique hybrid of A. aflatunense and A. macleanii.
With a hardiness range spanning Zones 4-10, this versatile perennial can be enjoyed by gardeners across the country.
Globemaster
Globemaster, a captivating hybrid of A. cristophii and A. macleanii, boasts enormous purple blooms that can reach up to eight inches in diameter, supported by sturdy four-foot stalks. This impressive variety thrives in a range of environments, specifically suitable for Zones 4-10.
His Excellency
This striking plant boasts vibrant purple robes and produces enormous five-inch blooms on sturdy four-foot tall stems, earning it a resemblance to a grand display of chives. Its hardiness makes it an ideal choice for gardeners in USDA Zones 4-8.
Mars
The ‘Mars’ variety boasts vibrant reddish-purple blooms that rise above sturdy stems measuring around three feet tall. What’s more, this cultivar has earned a reputation for being a dependable performer in USDA Hardiness Zones 4 through 9, making it an excellent choice for gardeners seeking a low-maintenance yet visually striking addition to their outdoor spaces.
Mount Everest
The majestic ‘Mount Everest’ allium boasts remarkable features, including its show-stopping blooms which grow atop sturdy stems that reach up to three feet tall. This impressive variety is well-suited for zones 4 through 9, making it an excellent choice for gardeners seeking a statement piece in their outdoor spaces.
Moly
Unlike many ornamental allium varieties, Allium moly stands out with its striking star-shaped yellow blooms, radiating warmth and vitality into the garden. Often referred to as ‘lily leek’, this hardy perennial thrives in a wide range of climates, making it an excellent choice for gardeners in USDA Zones 3-9.
Pinball Wizard
The ‘Pinball Wizard’ succulent, a cross between Aloe macleanii and Aloe christophii, is a compact gem that stands at just two feet tall. Its striking features include giant purple heads with subtle hints of lilac and silver, which seem to shift in color depending on the angle of the sunlight. This stunning variety thrives in zones 3-8, making it an excellent choice for gardeners who want to add a pop of color to their outdoor spaces.
Star of Persia
The Star of Persia (Allium cristophii) is an extraordinary variety that truly shines with its striking appearance. Its enormous flower heads reach up to 10 inches in diameter and boast a deep reddish-purple hue, but the true showstopper is the individual blooms on the inflorescence. Each tiny flower resembles a miniature star, resulting in a mesmerizing ‘ball of stars’ effect atop a robust plant that can grow up to 20 inches tall. This stunning allium variety thrives in USDA zones 5-8.
Tumbleweed Onion
The Tumbleweed onion (A. schubertii) is a visually striking addition to any garden, with its delicate white flowers resembling tiny fireworks bursting forth. Standing at just 20 inches tall, this compact beauty can produce a copious amount of blooms that are sure to captivate anyone who lays eyes on it. Its versatility makes it an ideal choice for gardens in Zones 4-10.
Planting Ornamental Alliums in Your Garden
Ornamental alliums are adaptable and can thrive in USDA Growing Zones 3-10, with some varieties even tolerating Zone 2 conditions when provided with winter protection. One of the distinguishing features of these plants is their long, slender leaves and unique flowers that often form clusters in star-shaped, cup-shaped, semi-circular, round, or pendulous arrangements.
When selecting a location for ornamental alliums, aim to place them in a spot that receives full sun with at least six hours of direct sunlight each day. While they can tolerate partial shade, providing maximum exposure to light is ideal. Soil quality is also crucial; these plants prefer well-draining soil with a slightly acidic pH range of 5.5 to 6.5.
However, if the pH level isn’t exactly what’s desired, it’s still possible to grow ornamental alliums successfully as long as the soil drains well and root rot is prevented. An added advantage is that these plants can be grown in containers, providing an extra layer of flexibility when choosing where to place them.
Planting Bulbs
When planting ornamental alliums, it’s essential to consider the proper technique and timing. Autumn is an ideal season for bulb planting, allowing you to prepare in the summer months. To begin, dig a hole that’s approximately four times the diameter of the bulbs. If you’re planning to grow multiple plants, ensure sufficient spacing between them. For smaller alliums, a 3-4 inch gap is suitable, while taller varieties require around 8 inches of separation.
If you prefer to cultivate ornamental alliums in containers, select a deep pot and fill it with well-draining soil, such as a general-purpose potting mix. This will provide the necessary conditions for your plants to thrive.
Looking After Ornamental Alliums
When it comes to caring for your allium plants, one of the most important considerations is their watering needs. Fortunately, many allium varieties are relatively drought-tolerant and can survive a short period without water. However, this doesn’t mean you can completely abandon them – in fact, regular watering is still essential for optimal health and growth. Ideally, aim to keep the top inch or two of soil moist between waterings.
Just be aware that rhizomatous alliums, which have underground stems rather than bulbous roots like some other varieties, tend to require a bit more moisture overall.
Fertilizer
While fertilizer isn’t an absolute necessity for cultivating these plants, a well-balanced formula can be particularly beneficial when dealing with poor soil conditions. In such cases, the added nutrients can help sustain optimal growth and overall plant health. On the other hand, if your soil is already relatively fertile, you likely won’t need to supplement your plants’ diet.
Deadheading
As ornamental alliums reach their full splendor, it’s impossible not to be captivated by their vibrant displays. Even as they begin to wilt and transition into seed production, they can still bring a unique tactile element to your garden. If you wish to maintain a pristine appearance or prevent unwanted self-propagation, consider deadheading the plant after it blooms. This involves cutting off the spent flowers to keep the plant tidy.
Not all allium varieties are fertile, but many are, and if left unchecked, they’ll happily spread their seeds far and wide. On the other hand, you might choose to leave the seed heads intact, allowing them to provide a nutritious snack for visiting birds.
Common Pests and Diseases
This close relative of onions shares a susceptibility to similar ailments, making it crucial to monitor your plants regularly. For instance, our comprehensive guide provides valuable insights into the most prevalent afflictions affecting this plant. To stay ahead of the game, schedule regular checks on your plants every few days, allowing you to detect early signs of these diseases before they spread and cause irreparable damage.
Onion White Rot
Ornamental alliums are susceptible to onion white rot, a fungal disease that targets foliage and leads to root decay. The culprit behind this issue is Stromatinia cepivora (syn. Sclerotium cepivorum), which can remain dormant in soil for years if left untreated. Be on the lookout for these telltale signs: yellowed leaves, wilting, and root rot. Additionally, you may notice white, fluffy fungal growth around the bulb’s base.
Unfortunately, once the disease takes hold on the bulb, it’s challenging to eradicate completely. However, there are some treatments worth exploring. For more information, consult our comprehensive onion disease guide. If removal is necessary, consider avoiding planting anything from the allium family in that area for at least a few years or opt for solarization techniques to kill off any pathogens and prevent future outbreaks.
Onion Downy Mildew
Peronospora destructor, a fungus-like organism, poses a significant threat to both onions and ornamental alliums. The hallmark symptoms of this disease include yellowing leaves, the development of white mold, and shriveled bulbs. To prevent infection, it’s essential to avoid overcrowding your plants and promptly remove any diseased areas.
Unfortunately, there is no chemical solution available for treating this disease, making preventative measures crucial for maintaining healthy and thriving plant populations.
Snails and Slugs
When it comes to ornamental alliums, two pests can cause significant damage: snails and allium leaf miners. One telltale sign of a snail infestation is the presence of slimy trails in your garden. If you notice these unwanted visitors leaving their mark, consider consulting our comprehensive guide for effective natural methods to control their populations.
Allium Leaf Miners
The pesky Phytomyza gymnostoma, also known as ornamental allium pests, are notorious for infesting these plants. Adult flies lay eggs on the alliums, which then hatch into larvae that feed slowly on the plant’s foliage. The adult flies themselves are a mere 3 mm long and grey in color, while their larvae take on the form of white, 8 mm long maggots.
To effectively manage an allium leaf miner infestation, it’s essential to employ a barrier method, such as insect-proof covers, to prevent the flies from depositing eggs. For further guidance on tackling this issue, refer to our comprehensive guide.
