How to Grow Alliums

Alliums are stylish plants with tall stems and large blooms. They look fantastic in the borders with the large pom pom heads of flowers. The good news is that Alliums are easy to grow and return reliably every year.   

Alliums are tall and their large flower heads are in shades of purple, white and occasionally blue and yellow. Alliums are bulbs, easy to grow and almost trouble free. The only maintenance required for Alliums is that the taller species need staking unless planted in a sheltered spot away from wind. The different varieties of Allium bloom at slightly different times both spring, summer and autumn flowering.

Alliums are planted as bulbs in the autumn, and are also sold as ready grown container plants from early spring onward. It is significantly cheaper to buy and plant Alliums as bulbs.  Alliums prefer a sunny position in soil which is not waterlogged and are fully hardy. If you garden on heavy soil or ground that tends to be wet, it may help to work horticultural grit into the planting area to increase drainage.

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

A real plus point about Alliums is that they look good with many of our popular garden plants. Planted together on mass they are effective as in the large image  which was taken at RHS Harlow Carr.  Individual plants make an impressive single statement in the border, (top left) and the Allium illustrated is 'Globemaster'.

Alliums are just 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 the seed heads form as illustrated below right.

The downside of growing Alliums, if there is one, is that the leaves at the base of the plant can look a bit tired, or ragged quite 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 and Geraniums which look well with Allium. 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 later flowering Allium such as sphaerocephalon.

Alliums are loved by bees and insects and given a warm day the large flower heads will be buzzing. They 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. 

   If Allium is not the plant for you check out other spring flowering plants, scented plants and climbing plants for more ideas.    

Of course, 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. 

Many varieties of Allium are illustrated here.

Very popular Alliums with the RHS garden merit award are:

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.

Images Above: image first left Globemaster which is summer flowering and grows up to 100cm.

Centre is Allium sphaerocephalon which flowers in late summer and  looks very good with grasses which are at their best in late summer and early autumn.

In the third image, 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.