How to Grow Alliums

Alliums are stylish plants with tall stems and large blooms which look fantastic in borders with large round flower heads. The good news is that Alliums are easy to grow and are a perennial which generally returns reliably every year.   

Alliums flower in shades of purple, white and occasionally blue and yellow. Alliums are bulbs and almost trouble free. The only maintenance required for Alliums is that the taller species need staking to prevent the flower stem from being damaged, unless planted in a sheltered spot away from wind. Although Alliums are in the section of spring flowering, it is true to say the majority are spring and early summer flower. There are some varieties which flower during late summer. 

Alliums are loved by bees and insects and on a warm day the large flower heads will be buzzing. They will also attract butterflies and are a great source of nectar.

Allium showing base leaves

The downside of growing Alliums, if there is one, is that the leaves at the base of the plant can look tired, or ragged early on in the growing season.   This means it's a good idea to conceal the base growth with low growing plants, such as the Alchemilla mollis, Hosta and Geraniums all of which look well with Alliums. There are a number of planting combinations illustrated below which will look stylish and ensure the base leaves are covered. If you look closely at the image on the left, you will see the brown tips on the Allium leaves which can look unsightly. 

How To Plant Alliums

Alliums are best planted in the autumn when you can buy bulbs at a reasonable price. Ready grown container plants are available from early spring onward but naturally these are more expensive. It is significantly cheaper to buy and plant Alliums as bulbs.  Alliums prefer a sunny position in soil which is not waterlogged and they are fully hardy tolerating our winters well. However, if your garden has heavy soil or ground that tends to be wet, it will help to work horticultural grit into the planting area to increase drainage. This should prevent the bulb rotting over winter which can be a problem in wetter areas.

When planting Alliums, in common with many bulbs,  plant to 3 times the depth of the bulb and plant the pointed end upward.

Smaller varieties should be planted 15-20 cms apart, large varieties (such as a.cristophii)  25-30cms and the very large ( such as Globemaster' and schubertii)35cms+ 

Like all bulbs, do not cut or clear away the old foliage after flowering as this is needed to photosynthesise and feed the bulb for next year.

Alliums are drought tolerant, generally do not need feeding or dead heading, quite the reverse as many of the flower heads look very decorative as they fade. 

Green wheelbarrow means Alliums are easy to grow and low maintenance

The Best Alliums to Grow

 

Individual plants make an impressive single statement in the border, (top left) and the Allium illustrated is 'Globemaster'.

Alliums are made to mix with grasses and look good with Achillea (2nd image centre). Alliums are predominately purple flowering although there is a blue form, careruleum, and a very attractive yellow variety, Allium moly (golden garlic) which has umbel type flowers in the summer. Alliums have an additional bonus that the flower heads look good as they fade and as the seed heads form, illustrated below right.

 If you are combining with other plants check the variety to ensure the flowering times coincide. To plant the combination of grasses and Alliums illustrated centre above and below left it is essential to plant a late flowering Allium such as A. sphaerocephalon so that it is at its best when the grasses are looking good and the Achillea in flower.

Alliums are members of the onion family and the small Allium schoenoprasum, Chives, are good to eat and make a lovely edging plant front of the border and are wildlife friendly. 

 Allium are illustrated here:-

A. cristophii (image top right) is short at 60cms with spiky flower head which will self seed in the right conditions;

A.hollandicum (image below) 'Purple Sensation' tall 80cms dark purple;

A. Globemaster 100cmc with large deep purple flower heads.

Centre image above is Allium sphaerocephalon, a late summer flowering variety. It looks good planted with grasses which are at their best in late summer and early autumn, and also with late flowering perennials such as Rudbeckia and Helenium.

In the third image above is the very attractive A. christophii which flowers in the late spring and early summer, with spiky flower heads which look very good as they fade and dry.

Alliums in the Border

Alliums in Border close up

This is the same border in both images. On the left a closeup of Alliums grouped together looking stunning. 

On the right showing how the Alliums have been repeat planted along the border to great effect. The left image was taken from the bench which is in the corner of the right image. All taken at Beningbrough Hall, a good garden for a visit.

Alliums in border long shot

Varieties of Allium

Allium christophii

Allium christophii

Allium Globemaster

Allium Globemaster

Allium sphaerocephalon

Allium sphaerocephalon

Allium 'White Giant'

Allium white giant

Allium 'Pinball Wizard'

Allium 'Pinball Wizard'

Allium schubertii

Allium schubertii - Schubert`s allium

Blue Allium caeruleum

Allium nectaroscordum

allium nectaroscordum siculum

Best Allium Planting Combinations

Allium hollandicum ‘purple sensation’ with Euphorbia palustris

For contrasting colours: Allium 'Purple Sensation' with Euphorbia palustris which make a great contrasting combination. This is a late spring early summer combination.

Allium stipitatum ‘white giant”

Simplicty: Allium stipitatum White Giant which looks really good planted as a group with the wall as a backdrop.

Alliums planted en masse

For a Soft Blues and Mauve combination: Alliums grouped together look impressive this and the large image below was taken at RHS Harlow Carr. In this iamge Alliums are plant with a blue variety of Camassia. This is a good blue/purple combination bearing in mind Camassia may not be fully hardy everywhere in the UK.

Deschampia grasses with Alliums

Late summer combination: Alliums and grasses are natural companions; this combination is Deschampsia grass with Allium sphaerocephalon, a soft billowing grass making a rich late summer/autumn display combined with the deep purple Allium and just a little blue mixed in from the Nigella damascena common name "love-in-a-mist'.

Allium chives, in wildflower setting with campion and for get me nots

Wildlife friendly combination: Chives with forget me nots and Campion. It is easy to overlook A. schoenoprasum, Chives, is small but ideal for edging and at the front of a border and it is very bee friendly. Chives flower for weeks and can be cut back to produce fresh growth and a second set of flowers.

Fading flower heads of Alliums

Staying Power: Allium fading flower head last for along time looking impressive. This image shows the delicate beauty of the fading flower heads. Alliums belong to a unique group of plants whose flowers look really good as they fade, (think also Hydrangea, and Achillea.)

Allium schubertii, with candelabra primular and blue geranium 310

Great spring combination: The architectural spikey Allium schubertii, with candelabra primula and a hardy blue geranium makes an easy to grow colourful combination

Allium against a backdrop of clematis montana

A soft colour combination of Allium Globemaster against a back drop of the spring flowering Clematis montana makes an interesting combination.

The RHS always know how to put on a great display and this is Alliums on mass with grasses growing at RHS Harlow Carr, something to aspire to. 

Allium and grasses at RHS Harlow Carr

Key Points to Growing Allium

Fully Hardy 

Enjoys sun and well- drained soil

Plant the Allium bulb in autumn 3x its depth 

 Support tall varieties. 

Easy to grow, reliable performer flowers every year.

Updated 17.10.2019