How to grow alliums

No other plant or flower attracts quite such admiration in borders and beds than wonderful alliums. They’re architectural, loved by bees and are ideal cut or dried flowers. Order and plant bulbs in autumn for a spring display.

Allium colours vary. However, most range between purple and lilac. The darker-purples tend to be hardier than the more silvery mauves.

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When to plant allium bulbs

Allium bulbs are planted in early autumn and they will flower next year and for a few years after that if they are prevented from self-seeding. Buy allium bulbs from a reputable supplier who will sell you good forms of the correct thing. Be prepared to pay more for the larger allium bulbs, they take many a year to produce.

Where to plant allium bulbs

Alliums are generally plants of sunny and well-drained soils.

If you plant a pale allium find it a warm spot. The white forms look more handsome in semi-shade.

Alliums can be grown in alpine screes. Read our guide to creating an alpine scree garden

How to plant alliums

Plant allium bulbs at twice the depth of the bulb, four to five inches deep (10-12.5cm) and about a foot apart (30cm). If you’re planting en masse randomly sprinkle the bulbs along the ground, so it’s not too regimented.

Removing seedpods

As the allium flowers fade some will develop seedpods and these need to be removed before the black seeds escape and create a sea of grass-like seedlings. If allowed to self-seed the bulbs will not be replenished. 

Some varieties are sterile and do not set seed and their seed heads can be left to fade without fear.

Feeding

Feed alliums every spring with a potash-rich fertiliser such as Vitax Q4.

Maintenance

Do not let alliums self seed! They will produce hundreds of grassy nuisances. Top up with more bulbs in the autumn, as necessary, and divide clumps in early autumn, if you need to.

Wildlife

Alliums will attract bees and butterflies.

Find out how to create a bee-friendly garden

Plant with…

The taller varieties of alliums make useful verticals in a border and they do not need staking due to their stiff stems. However, their leaves emerge early and dies back long before the flowers appear, so foliage tends to be shabby by the time alliums are in flower and it’s best to have them growing through lower-growing herbaceous plants so that this is hidden. Low-growing hardy geraniums, Alchemilla mollis and the silvery leaves of Artemisia ‘Powis Castle’ will hide any unsightly leaves.

They look just as well in a flower border as they do on the edges of a vegetable garden, so they can be grown under standard gooseberries, or under standard roses. They should be woven through a border so are best ordered in 50s or 100s. However, some hybrids are very expensive so generally the cheaper varieties are planted en masse with stands of a few bulbs of the most expensive ones.

Alliums are perfect for a contemporary garden. Read our guide to designing a contemporary garden

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Allium 'Purple Sensation'

Best allium varieties

Allium hollandicum ‘Purple Sensation’ AGM
The deep-purple spheres appear just after the late-tulips so this is a good addition to a border where late tulips have already flowered. It flowers by mid-May and the flowers fade beautifully, quite quickly but give weeks of interest. Very cheap to buy: this allium does produce seeds so do remove the heads. It was a selection from A. aflatunense made by Mr J. Bijl in 1963. It can be grown very effectively with blue or cream coloured Camassia leichtlinii semi plena, hardy geraniums such as 'Orion', Nepeta 'Six Hill's Giant', Polemonium 'Lambrook Mauve' or Alchemilla mollis to hide the foliage, which can be unsightly by spring. It can also be planted among roses or in a potager-style vegetable garden. (30"/75cm).

Allium 'Ambassador'
A 15cm (6in) fuzzy round head of purple stars that goes on and on throughout June and July without fading in colour. Robust and reliable, year after year, and there are no seeds. Height 1m (3ft 3in). The bulbs are massive, so best grown as a clump that can pop up behind airy taller grasses such as Stipa gigantean. Or plant en masse through late-summer perennials or in front of a golden philadelphus. Plant bulbs at least 15cm (6in) deep. Remove seedhead in autumn by pulling it away gently, and bulbs will return year after year. Needs good soil and light.

Allium ‘Mount Everest’
This hybrid of Allium stipitatum and Allium aflatunense, raised by A Langedijk, has glossy green stems with one flattened edge. The white heads measure 4-5" (10-12.5cm) across and reach 3 ft in height (90cm), flowering in May to June. This is often planted with a yew hedge backdrop. Roughly four times as expensive as ‘Purple Sensation’ (36" /90cm).

Allium ‘Firmament’
Raised by A. Langedijk from a cross between Allium atropurpureum and Allium cristophii, it has deep purple flowers with a metallic sheen and the heads are flattened at the base. It is June-flowering - so extends the season. Expensive though, expect to pay almost £4.00 per bulb. This is extremely good with silvers, as it gleams in sun (24"-30"/60cm-75cm).

Allium ‘Globemaster’ AGM
A shorter allium with larger, perfectly spherical heads eight-inch wide in deep, violet-purple that flower from late May and lasts a long time. There’s often a second flush of flower and the foliage is much tidier than most. Bred by J. Bijl in 1971 and a hybrid between A.chrisptophii and A. elatum. Expensive - between £3.00 and £6.00 per bulb. A clump of five will make a statement in any mixed border, but it’s very good in front of dark Cotinus foliage, or used against Sambucus ‘Black Lace’, a cut-leaved elder (36"/90cm). It looks good planted with equally bold-leaved plants such as the golden-leaved Hosta 'Sum and Substance'. This allium is one of the best at returning again and again and if you leave clumps undisturbed you will get more flowers, but of a slightly smaller size.

Allium ‘Gladiator’ AGM
Another hybrid that forms a large lilac-purple completely round ball. This hybrid between A. aflatunense and A. elatum was from W. Hey in 1981 (36"/90cm).

Allium ‘Giganteum’ AGM
The most expensive bulb usually, but well worth it because this is taller, reaching four feet in height. The flower is grapefruit-sized with lots of flowers that form a fuzzy ball, but this is a species found on lower mountain slopes in Central Asia, introduced in 1883.

Allium 'Silver Spring'
The most feminine early summer-flowering allium of all, with thickish green stems topped by a posy of white-petalled flowers, 7-10cm (3-4in) across, with blackcurrant-purple centres. Height up to 90cm (3ft). Grow with perennial violas such as ‘Belmont Blue’, or the variegated thyme ‘Silver Posie’ or ‘Silver Queen’ to hide the foliage, which emerges early. Good drainage is vital, so this is a candidate for a container or a sunny corner. Not a great returner, so bulbs will need replacing regularly. Seedlings do come true to type though, so if you’re prepared to wait, collect the seed and sow in trays rather than leaving it to chance.

Allium varieties (clockwise from top left): Allium 'Gladiator', Allium sphaerocephalon, Allium 'Mount Everest' and Allium 'Globemaster'

Allium 'Purple Rain'
This flowers least a month later than ‘Purple Sensation’, with long-lasting, vibrant purple stars held on radiating spikes. It’s the allium equivalent of a giant’s dandelion clock, but much more colourful. Height 1m (3ft 3in). Grow with Allium ‘Purple Sensation’ to lengthen the show, and weave it through borders, or let it pop up near green standard gooseberries, or mix it up with repeat-flowering roses, or lime-green euphorbias such as E. characias. This hybrid has the sun loving A. cristophii as a parent, so good drainage is vital. It multiplies well in the garden and will re-bloom consistently for at least five years. Divide in early autumn if clumps become too congested. Heads can be left to form a silhouette, without fear of it seeding everywhere.

Allium sphaerocephalon
The drumstick allium from Europe, Northern africa and west Asia has a slender stem topped with a small oval flower that opens to green and colours to maroon. Highly effective with achilleas and the ponytail grass, Stipa tenuissima, and eryngiums. This July-flowering allium is cheap and effective. It rarely sets seed for me (24" /60cm).

Allium schubertii
This is a tumbleweed in the wild, found in the Eastern Mediterranean so find it the hottest, driest spot of all so that it overwinters to produce its late-June firework-come-sputnik some 18 inches across. The longest flower stems are sterile, but the shorter spikes produce lots of seeds. More of a curiosity than a good garden plant 18" (45cm).

Allium cristophii AGM
This also needs a hot spot and good drainage in order to overwinter as it’s found from Central Asia to Iran on rocky slopes. It was first described in 1884 and the round June flower head consists of between 50 and 70 starry flowers, each with a metallic sheen. 10 -16" (25-40cm). This makes a feature plant at the front of a border.

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