How to grow Alliums
Alliums are an easy to grow perennial bulb, which usually returns reliably every year.
Alliums come in a wide range of heights, from low growing chives to the tall varieties such as A. allium giganteum which can reach 1.5m. They are mainly late spring/early summer flowering, although there is a late summer flowering variety of Allium, A. sphaerocephalon. Alliums flower in shades of purple, white and occasionally blue and yellow. Although there is a long list of Allium pests and diseases, in the garden Alliums are almost trouble free. The only maintenance required is for the taller species, which need staking to prevent the flower stem from being damaged, unless planted in a sheltered spot away from wind. Bees and insects love alliums, and on a warm day the large flower heads will be buzzing and they will also attract butterflies.
The downside of growing Alliums, if there is one, is that the leaves at the base of the plant can look tired, or ragged even early in the growing season. If you look closely at the image on the left, you will see the brown tips on the Allium leaves, which can look unsightly. To cover this, 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 several planting combinations illustrated below which will look stylish and ensure the base leaves are covered.
How To Plant Alliums
Allium Bulbs are best planted in the autumn when the bulbs are cheaper than buying pot-grown plants in the Spring. Best planting time is September, but if you are late, you can carry on planting Allium bulbs until about the 3rd week of October.
Alliums prefer a sunny position in soil which is well drained and they are drought tolerant. Alliums are fully hardy tolerating our winters well. However, if your garden has heavy soil or ground that is wet and boggy over the winter, there is a risk the bulbs could rot. To prevent this dig in horticultural grit to increase drainage.
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. This is needed to photosynthesise and feed the bulb for next year.
Alliums are drought tolerant, and generally do not need feeding or dead heading, quite the reverse as many of the flower heads look decorative as they fade.
Green wheelbarrow means Alliums are easy to grow and low maintenance
Chives are one of the smallest forms of Allium and a bee and butterfly magnet. The brief video clip shows pollinators on Allium nutans, also known as Siberian Chives, which are a great favourite. Often plants are described as "good for pollinators," here is the material evidence which should give you confidence when planting them.
The Best Alliums for your garden
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.
Alliums are members of the onion family and the small Allium schoenoprasum, Chives, are good to eat and make a lovely edging plant in the front of a border and are wildlife friendly.
Great looking alliums to grow include:
- 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 (image top left) 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.
- Allium 'White Giant' below right, as the name suggests, a lovely white variety.
- A. 'Pinball Wizard' mauve with a more fluffy flower head.
- A. Schubertii has a very spikey flower head
- Blue Allium caeruleum a strong blue variety
- Allium nectaroscordum an unusual variety with nodding umbel flowers
Allium christophii
Allium Globemaster
Allium sphaerocephalon
Allium 'White Giant'
Allium 'Pinball Wizard'
Allium schubertii
Blue Allium caeruleum
Allium nectaroscordum
What to plant with Alliums - Best Planting Combinations
Allium 'Purple Sensation' with Euphorbia palustris
Allium 'Purple Sensation' with Euphorbia palustris which make a great contrasting combination. This is a late spring and early summer combination.
Both plants are low maintenance, making it an easy to grow combination.
Allium with Persicaria bistorta 'Superba'
A great planting combination of Allium with pink Persicaria bistorta 'Superba'. Both plants are long flowering and will attract bees and butterflies. I took this image in the botanical garden at Leicester University, which has a fabulous display of Alliums from mid May onwards. (and it's free.)
Blue spires of Camassia with purple Allium
Camassia with purple Allium- two bulbs grown together make a great late spring early summer planting combination.
Bulbs are easy to grow and Camassia has lovely soft blue flowers which open from the base upwards. Camassia growing tips
Allium sphaerocephalon, with deschampsia Nigella
This is a late flowering combination from July onwards. Allium sphaerocephalon with fluffy grass deschampsia and the blue Nigella, the annual love-in-a-mist. I took this image at RHS Harlow Carr an impressive combination.
Chives, campion and forget-me-nots.
Wildlife friendly planting combination of Chives, campion and forget-me-nots. Bees just love Chives as the video above shows. They also make a great edging plant. Cut back after flowering for a second flush.
Allium combined with he early flowering Clematis montana
Purple Allium combined with soft creamy white of the early flowering Clematis montana.Ideal planted against a fence they make a lovely planting combination. C.montana is a group 1 for pruning so easy to grow.
Styling Alliums in the border
This is the same border in both images taken from a different position. 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. I took the left image from the bench which is in the corner of the right image. All taken at Beningbrough Hall, a good garden for a visit.
The RHS always know how to put on an impressive display and this is Alliums on mass with grasses growing at RHS Harlow Carr, something to aspire to.
last updated 13.01.2024