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Purple alliums blooming

How to grow alliums

All you need to know about growing alliums, or ornamental onions, in our Grow Guide.

A table displaying which months are best to sow, plant and harvest.
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Plant

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Do not Plant in December

Flowers
Flowers

Plant does not flower in January

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Cut back

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Do Cut back in July

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Do not Cut back in September

Do not Cut back in October

Do not Cut back in November

Do not Cut back in December

Alliums are bulbous perennials, Incredibly long-lived, they bloom for weeks on end, bridging the gap between spring and summer. Loved by bees, alliums bear beautiful pompom flowers in shades of purple pink and white, and look fantastic when planted in large groups. Alliums make excellent cut flowers, both in fresh and dried flower arrangements.

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How to grow alliums

Grow alliums in moist but well-drained soil in full sun. It’s a good idea to grow them among low-growing herbaceous plants, which hide their unsightly strappy foliage after flowering. Let allium foliage die down naturally after bloomig and consider leaving the flowerheads in place as they look attractive in their own right, particularly in winter. Mulch annually with well-rotted compost or manure.

Alliums: jump links

More on growing alliums:


Choosing alliums

When choosing alliums to grow, think about your garden space. Will you be growing in drifts through the border or planting in bulk, in pots? As part of a prairie planting scheme or something more formal? It’s also important to think about the colour of your alliums – most allium flowers are purple but some come in shades of blue, white, yellow and pink. Also consider the size of your allium – that’s the flower size as well as the overall height of the plant. Flower sizes range from just a few centimetres to over 20cm (8in) in diameter, while the eight of alliums can vary significantly, too.

Large, tall alliums such as ‘Purple Rain’ and ‘Globemaster’ work well when planted individually or in drifts. Shorter varieties such as Allium christophii work well in pots. Drumstick alliums such as Allium sphaerocephalon look great in prairie planting schemes.


Where to plant alliums

How to grow alliums - allium blooms against a blue sky
How to grow alliums – allium blooms against a blue sky

Alliums do best in a sunny spot in a very well-drained soil. They’re not fussy about soil type. Plant taller varieties towards the back of a border and shorter-growing types in the front. Alliums are well suited to growing in pots but their strappy foliage can look unsightly after flowering.

Alliums produce foliage before the flowers appear. This often means they’re better suited to the middle of a border where the faded foliage will go unnoticed while the flowers put on a show. To avoid seeing the faded foliage, plant alliums in amongst ornamental grasses and perennials.

For a dramatic display, grow alliums in large drifts through the border or naturalise them in your lawn.


How to plant alliums

How to grow alliums - planting an allium bulb
How to grow alliums – planting an allium bulb

Plant allium bulbs in autumn, at least four times the depth of the size of bulb (at least 15cm deep). It’s better to plant them too deeply than too shallow.

If the soil is moist there’s no need to water them in. In spring, when growth starts to appear, apply a balanced fertiliser to poor soils.

Watch our No Fuss video guide with Rosie Yeomans, to learn how to layer allium bulbs with others in a pot:


Where to buy alliums online

How to care for alliums

How to grow alliums - allium seedheads
How to grow alliums – allium seedheads

Taller types may require support in exposed positions. Once the flowers have faded leave them on the plant until they fall apart as they offer fantastic winter interest. Some gardeners pick the seedheads and dry them in order to use them as a decoration in the house.

Allium bulbs can be left in the garden year after year. Try to remember where you’ve planted bulbs so you don’t damage them when planting new plants.


How to propagate alliums

After a few years allium bulbs will multiply. In some cases you’ll notice the white bulbs being pushed out of the soil. In late autumn or very early spring carefully lift the bulbs and gently peel off the offsets to replant straight into the soil.

To grow allium from seed leave the flowerheads on the plant and collect the ripe seed and sow it straight away. bear in mind that growing alliums from seed is a long process, as it will be years before you achieve a flowering plant.


Growing alliums: pests and problem solving

Allium white rot is a fungal disease, which inhibits the growth of onions and other alliums. To prevent recurrent infections, clear and burn the affected plant material and avoid planting alliums in the same position for at least five years.

Alliums can out-grow their space. Find out how to reduce the number of alliums growing in a border, in this video clip from Gardeners’ World:

Advice on buying alliums

  • Carefully sesearch the height and spread of your alliums before buying them, so they will fit well into your garden design
  • Choose firm bulbs with no sign of mould, and plant them at theor freshest, ideally within a week of buying

Where to buy alliums online

20 alliums to grow

1

Allium sphaerocephalon

Best alliums to grow - Allium sphaerocephalon
Best alliums – Allium sphaerocephalon

The drumstick allium, Allium sphaerocephalon, is a striking allium, bearing dense green drumstick-style flower heads which mature to maroon-red. It’s a great choice for growing in a mixed herbaceous border among ornamental grasses, or gravel gardens. It also works well in pots.

H x S: 90cm x 8cm


2

Allium christophii

Best alliums to grow - Allium christophii
Best alliums – Allium christophii

Allium cristophii produces striking globes of violet, star-shaped flowers in early summer. The long, linear leaves die back before the blooms appear in early summer.

H x S: 60cm x 20cm


3

Allium decipiens

Best alliums to grow - Allium decipiens
Best alliums – Allium decipiens

Allium decipiens is native to Central Asia and China. It bears pretty clusters of lilac-pink, star-shaped flowers on tall stems. It’s a fantastic choice for growing in sunny borders and patio container displays.

H x S: 90cm x 10cm


4

Allium ‘Millennium’

Best alliums to grow - Allium ‘Millennium’
Best alliums – Allium ‘Millennium’

Allium ‘Millennium’ is a fantastic mid- late-summer-flowering allium, bearing large, rounded heads of pink-purple flowers in June and July. It’s perfect for growing in a mixed herbaceous border and is best planted in large groups.

H x S: 40cm x 45cm


5

Allium cernuum

Best alliums to grow - Allium cernuum
Best alliums – Allium cernuum

Allium cernuum is a clump-forming allium, bearing open clusters of pink, nodding flowers with protruding yellow stamens. It’s an extremely attractive variety and is easy to grow. It’s perfect for growing in a mixed herbaceous border or in drifts as part of a prairie scheme.

H x S: 50cm x 10cm


6

Allium ‘Globemaster’

Best alliums to grow - Allium 'Globemaster'
Best alliums – Allium ‘Globemaster’

Allium ‘Globemaster’ bears rounded, deep violet flower heads, 15-20cm in diameter, from late spring to early summer. It works well when planted in drifts with ornamental grasses and other alliums, including lighter flowered ‘Beau Regard’.

H x S: 1m x 50cm


7

Allium nevskianum

Best alliums to grow - Allium nevskianum
Best alliums – Allium nevskianum

Hailing from Afghanistan and Tadjikistan, Allium nevskianum is a low-growing and rarely grown allium, bearing large, deep red globular flower heads above attractive, large blue-grey leaves. Grow it at the front of the border or make a feature of several planted together in a pot.

H x S: 30cm x 20cm


8

Allium ‘Mont Blanc’

Best alliums to grow - Allium 'Mont Blanc'
Best alliums – Allium ‘Mont Blanc’

Allium ‘Mont Blanc’ bears dense, spherical flower heads of white, star-shaped flowers on tall, upright stems in late-spring and early summer. It’s a great choice for sunny borders and gravel gardens, where it can be planted in clumps, or drifts among ornamental grasses and other alliums. It makes a wonderful cut flower.

H x S: 1.1m x 20cm


9

Allium schubertii

Best alliums to grow - Allium schubertii
Best alliums – Allium schubertii

Allium schubertii is an unusual-looking allium, bearing spiky heads of flowers with stems of different lengths, resulting in a dramatic effect. Individual florets are purple with a green centre. It’s perfect for growing in sunny borders and in pots as an unusual centrepiece, and it makes a striking cut flower.

H x S: 50cm x 25cm


10

Allium forrestii

Best alliums to grow - Allium forrestii
Best alliums – Allium forrestii

Allium forrestii is a rare dwarf species of allium, native to meadows and gravelly slopes of China. It has grassy foliage and delicate claret coloured flowers.

H x S: 25 cm x 10cm


11

Allium ‘Mars’

Best alliums to grow - Allium 'Mars'
Best alliums – Allium ‘Mars’

Allium ‘Mars’ bears well-formed, dark-red-purple, compact flower heads in late-spring and early summer. It’s is a fantastic choice for sunny borders, and works well when planted in drifts with ornamental grasses and other alliums.

H x S: 1.1m x 30cm


12

Allium ‘Purple Sensation’

Best alliums to grow - Allium 'Purple Sensation'
Best alliums – Allium ‘Purple Sensation’

The tall flowers of Allium ‘Purple Sensation’ appear in summer, showing off rounded heads full of deep violet flowers. It’s best to remove the immature seed-heads as the seedlings tend to have paler flowers.

H x S: 80cm x 30cm


13

Allium ‘Dready’

Best alliums to grow - Allium 'Dready'
Best alliums – Allium ‘Dready’

Allium ‘Dready’ is a cultivar of Allium vineale, as is related cultivar ‘Hair’. ‘Dready’ refers to the masses of dreadlock-like curling tendrils in green-red, which grow out from mauve drumstick flower heads.

H x S: 40cm x 10cm


14

Allium falcifolium

Best alliums to grow - Allium falcifolium
Best alliums – Allium falcifolium

Native to California and southern Oregon, Allium falcifolium is a relatively rare, low-growing alpine allium, bearing deep pink-purple shaggy flowers in late summer.

H x S: 20cm x 10cm


15

Allium amphibolum

Best alliums to grow - Allium amphibolum
Best alliums – Allium amphibolum

Allium amphibolum is a rarely seen drumstick allium hailing from Western China, having wiry stems and small, shaggy flower heads in light pink, with a sweet fragrance.

H x S: 40cm x 10cm


16

Allium ‘Purple Caila’

Best alliums to grow - Allium 'Purple Caila
Best alliums – Allium ‘Purple Caila

Allium ‘Purple Caila’ bears large flower heads of purple, star-shaped florets on tall, bare stems in late spring to early summer.

H x S: 20cm x 30cm


17

Allium ‘Red Mohican’

Best alliums to grow - Allium 'Red Mohican'
Best alliums – Allium ‘Red Mohican’

Allium ‘Red Mohican’ is a striking allium, bearing unusual, maroon-red drumstick-style flower heads with extra tufts at the top, tipped with tiny white flowers (resembling a mohican).

H x S: 90cm x 20cm


18

Allium rosenbachianum ‘Album’

Best alliums to grow - Allium rosenbachianum 'Album'
Best alliums – Allium rosenbachianum ‘Album’

Allium rosenbachianum ‘Album’ bears globular, flower heads of star-shaped white florets with a green eye. As they mature, the green eyes become seed cases held on thin stalks, to striking effect.

H x S: 80cm x 30cm


19

Allium ‘Purple Rain’

Best alliums to grow - Allium 'Purple Rain'
Best alliums – Allium ‘Purple Rain’

Allium ‘Purple Rain’ is a cross between Allium ‘Purple Sensation’ and Allium Cristophii. It bears huge purple, globe-shaped flower heads measuring up to 15cm in diameter.

H x S: 90cm x 30cm


20

Allium caeruleum

Alliums to grow - Allium caeruleum Imperata cylindrica 'Rubra'
Alliums – Allium caeruleum

Allium caeruleum is an unusual blue-flowered allium. It bears small, dense globes of star-shaped flowers on sturdy stems.

H x S: 60cm x 25cm

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