Alliums are part of the allium genus, which also includes onions, garlic, and leeks. While their edible cousins are found in the veg patch, ornamental alliums are stars of the flower border. Flowering in late spring and early summer, they provide a valuable bridge between the last of the tulips and the first of the high summer perennials.
Each flowerhead is made up of dozens, sometimes hundreds, of tiny star-shaped florets, arranged in perfect globes, domes, or drumstick shapes depending on the variety. They bring striking verticality and geometric interest to planting schemes.
Their structure remains attractive even as they fade into papery seedheads as they dry beautifully and can add structure to bouquets or dried arrangements, or you can leave them to stand in the garden over winter to offer seasonal structure as they dazzle in the frost.
Editor’s Tip
I dry my allium seedheads to use as Christmas decorations. Just give them a light spray with silver, gold, or white paint once fully dry to bring a little of the outdoors inside during December.
Those tiny florets are rich in nectar and are particularly valuable to bees, hoverflies, and other pollinating insects. Their shape provides a landing platform, and the open structure of the flowers makes it easy for pollinators to access the nectar. Their early summer flowering time also means they help bridge a seasonal gap in nectar availability.
Grasses like Stipa tenuissima enhance the striking silhouette of the alliums and the movement and texture of a grass can add a softness to a planting scheme.
While alliums look dazzling in bloom, their strappy base foliage begins to die back as they flower, often turning yellow and messy just as the flowers are hitting their stride. To maintain a tidy appearance, you can hide the foliage by planting them behind or within other herbaceous perennials. Ideal partners include:
• Nepeta (catmint) – airy and aromatic, with a billowy habit
• Hardy geraniums – low-growing and floriferous, they act as a green underlay
• Alchemilla mollis – the frothy lime-green flowers contrast beautifully with purple alliums
Growing Alliums in Pots
If you're short on space or want to make a bold statement on a patio, alliums grow beautifully in pots. This is also a great option for those with heavier clay soils or less than ideal drainage.
• Choose a pot at least 30cm wide and deep, with plenty of drainage holes.
• Use a gritty, free-draining compost: a mix of peat-free compost and horticultural grit or sand works well.
• Plant bulbs close together but not touching, about 10-15cm deep. Try grouping them in odd numbers for the most natural effect.
• Position in full sun, ideally against a warm wall or sheltered spot.
• Water sparingly in winter to avoid rot, and increase watering only as growth appears in spring.
• After flowering, let the foliage die back naturally and allow the bulbs to rest. You can replace the top layer of compost with fresh material and a little feed to encourage next year’s display.
Smaller varieties like Allium sphaerocephalon and Allium cristophii work particularly well in containers, but even larger types like ‘Globemaster’ can thrive with support and enough space.
• Free-draining soil is essential. Sandy loam or gritty soil works well. If you garden on clay, improve drainage with grit or plant in raised beds or containers.
• A sunny spot is key. Alliums need a good dose of sunlight to thrive and flower well.
• Plant bulbs in autumn, from September through early November. Earlier planting gives the bulbs time to establish roots before winter.
• Plant bulbs about three times their own depth, usually around 10–15cm deep, and space them 15–20cm apart, depending on the variety.
• Leave the foliage to die back naturally after flowering to allow the plant to recharge for next year. Removing leaves too early can reduce flowering the following year.
• Once planted, leave them undisturbed, they dislike being moved and will often naturalise well in the same spot for years.
Alliums are pretty drought-tolerant once established. In Scotland’s climate, you may only need to water them during particularly dry spells in spring. Avoid overwatering, especially in winter, to prevent bulb rot.
Incorporate a general-purpose bulb fertiliser or bonemeal into the planting hole in autumn. In spring, a top dressing with slow-release fertiliser or a light sprinkle of blood, fish, and bone will help support flowering.
Scotland’s cooler summers suit many allium varieties, particularly the hardier ones. Here are some reliable favourites:
• Allium hollandicum ‘Purple Sensation’: a Chelsea favourite, with vivid purple globes on 80cm stems. Hardy and easy to grow.
• Allium cristophii: known for its metallic, starburst-shaped flowers and wide, low-sitting globes. At 50cm in height, this one is ideal for more sheltered gardens or pots.
• Allium hollandicum ‘Globemaster’: reaching heights of 90cm with giant heads up to 20cm across, this is a bold choice for impact planting.
• Allium sphaerocephalon (drumstick allium): a later bloomer with egg-shaped flowers that start off green and turn reddish-purple. At 60cm high, these naturalise well and are ideal for containers or prairie-style planting.
• Allium stipitatum ‘Mount Everest’: a statuesque white-flowering variety that stands out in evening light and pairs beautifully with silver foliage or dark perennials like penstemon. Grows to 90cm high.
In the north and more exposed coastal areas, stick to the tougher varieties like ‘Purple Sensation’ and Allium sphaerocephalon, which cope better with wind and cooler temperatures. In milder parts of the Central Belt, you can experiment with larger-headed types like ‘Globemaster’ and ‘Ambassador’.
For an even longer display, stagger your planting with a mix of early, mid, and late-season varieties.
You can leave the flowerheads standing to catch the light or snip them off and bring them indoors, they dry beautifully and add structure to bouquets or dried arrangements. Leave seedheads to dry for winter structure or cut for dried flower arrangements.
Once you start growing alliums, it’s hard to stop. These stylish globes bring a touch of Chelsea magic to even the most ordinary border or balcony and they tick the box for both aesthetic appeal and ecological value.