Plant of the month - Alliums

Alliums are ornamental onions with large round, beautiful, bold, usually purple but sometimes white, heads of flowers. 

The flowerheads are followed by equally attractive seedheads, both of which are extensively used by florists for their arrangements.  

 Allium bulbs are widely available. The larger varieties produce impressive flower heads and make quite a statement if planted towards the back of a mixed border. The bulb’s full colour range is blue, purple, mauve, pink, yellow and white and the head diameter ranges from a few centimetres to 18-20 centimetres.  Tall alliums will grow to over 90cm but you can find them of all different heights. 

Most alliums flower in spring and early summer. For a later flowering variety try Allium Spaerocephalon for colour in July and August. All Alliums are very attractive to pollinators.  

The bulbs are best planted in early to mid-autumn at a depth of around four times the diameter of the bulb, so the larger bulbs, such as Alium Giganteum will need to be planted quite deeply - if only to avoid the need for staking. 

Alliums are such easy plants to care for provided they are planted in well-drained soil. Damp sites and/or heavy soil should be avoided.  They thrive in full sun, are drought tolerant and need little feed. The heads can be left on for an autumn display and they overwinter in the ground. Alliums are hardy so, if planted in the garden, the bulbs can be left undisturbed over the winter.  Plants in containers will need to be moved to a sheltered spot or into the greenhouse.

As with all such bulbs it may be preferable to plant them in an area of the garden where they are not disturbed by frequent digging - not least because the leaves die down after flowering. It makes sense to plant alliums where the foliage is masked by other plants.  

Popular alliums include, Allium cristophii, or Star of Persia, Allium hollandicum, or Purple Sensation, Allium Globemaster and Allium ‘Beau Regard’.