Like gardeners the world over, I absolutely adore alliums!
Also known as ornamental onions, these easy-to-grow perennials and their stunning spherical blooms bring texture, colour, and height to flower beds. Blooming in spring and summer, they also attract pollinators, and are a perfect addition to a wildlife friendly garden.
How to Grow Alliums
Alliums prefer a sunny spot, so a south or west facing border is ideal, though I have grown alliums on an east facing border with great success. North facing borders are also possible, though your alliums may not reach their full potential. Ideally find a spot where they get at least 6 hours of sunshine a day.
Whichever aspect, a sheltered location is always best.
Alliums prefer free draining soil, so if you’re on clay – which will feel heavy and very claggy in the wet, and rock hard in the dry – add some horticultural grit to help with drainage. If your bulbs sit in water for too long, they will rot.
Plant larger bulbs around 15cm-20cm (6-8 inch) deep, or 4 times the depth of the bulb itself. Planting too deep is better than planting to shallow!
Plant in groups but space out well. For smaller growing varieties, allow 7.5-10cm (3-4 inch) between bulbs, while taller specimens need at least 20cm (8 inch) separation.
Alliums are best suited to middle or back of the border, drifting among other plants which hide the allium foliage as it wilts during flowering.
The perfect time to plant your allium bulbs is in the autumn, ready for them to flower in spring and summer! Water weekly during dry spells.
Our Favourite Allium Varieties
Allium Giganteum
Height: 1.5-1.8 metres / 5-6 feet
Details: One of the tallest alliums producing large, globe-shaped purple flowers about 12-15cm (5-6 inch) wide that bloom in late spring to early summer. Their towering stems make them a focal point in garden borders.
Allium Globemaster
Height: 1 metre / 3-4 feet
Details: If you feel that bigger is always better, this variety has huge (20-25cm / 8-11 inch wide) purple, star-flowered blooms, which appear in late spring to early summer. Aside from a striking border display, these alliums are excellent for cut flowers, both fresh and dry arrangements. Just be sure you border will suit such large blooms before choosing this variety, which can sometimes looks a little unbalanced, depending on the surrounding plants and space.
Allium Hollandicum ‘Purple Sensation’
Height: 70cm-1 metre / 28-40 inches
Details: A very popular allium, ‘Purple Sensation’ displays its cluster of star shaped flower in late-spring early-summer. Beautiful 10cm-wide (4 inch) heads stand on sturdy stems, making this variety perfect for mixed borders and companion planting.
Allium Christophii (Star of Persia)
Height: 50-60cm / 20-24 inches
Details: Featuring silver-lavendar star-shaped flowers that form an open, airy globe. Allium christophii is a lower-growing variety that offers a unique, metallic sheen to its blooms.
Allium Schubertii
Height: 30-60cm / 12-24 inches
Details: This variety has one of the most dramatic appearances, with a firework-like pink-purple flower head spreading up to 30cm (12 inch) wide. A striking plant and a great choice for adding architectural interest to the garden.
Allium Stipitatum ‘Mount Everest’
Height: 1-1.2 metres / 3-4 feet
Details: A stunning contrast to the traditional purple varieties, ‘Mount Everest’ has pure white flower heads about 12cm / 5 inch wide. This variety adds brightness and elegance to borders, and looks fabulous mixed with a similar sized purple allium variety such as ‘Purple Sensation’.
Allium Sphaerocephalon (Drumstick Allium)
Height: 60cm / 24 inch
Details: With its small, reddish-purple oval-shaped flower heads, drumstick allium adds a whimsical touch to flower beds. This variety blooms later in summer, extending the allium season.
Allium Caeruleum (Blue Azureum)
Height: 60cm / 2 feet
Details: A small and beautiful blue-flowered allium producing striking sky-blue globes, about 5cm (2 inch) wide, that stand out beautifully. This allium blooms in early to mid-summer and pairs well with other alliums or contrasting warm-coloured flowers.
Final Thoughts
Alliums are versatile, low-maintenance, and visually stunning bulbous perennials that really enhance any garden. Whether you prefer towering purple globes or more dainty reddish-purple clusters, there’s an allium variety for you.
