Allium (Ornamental) Growing Guide

Allium (Ornamental)

Crop Rotation Group

Allium (Onion family) 


Average garden soil with excellent drainage.


Full sun.

Frost tolerant

Excellent. Most of the popular ornamental onions are hardy to -32C (-25F).


Topdress with rich compost in spring, when new growth appears. Fertilise with a liquid fertiliser in early summer, when the plants are in full leaf.


The rounded flowers of many ornamental alliums work like colourful exclamation points in mixed flowerbeds. The leaves appear before the flowering spikes. In late summer, use bushy annual flowers to hide the fading foliage of spring-blooming alliums from view.


Single Plants: 30cm (11") each way (minimum)
Rows: 30cm (11") with 30cm (11") row gap (minimum)

Sow and Plant

Set out dormant bulbs in the autumn, or transplant container-grown plants in early spring. Cover the bulbs to four times their depth with loose soil. Allow 30cm (12in) between bulbs of most varieties; very small species can be planted closer.
Our Garden Planner can produce a personalised calendar of when to sow, plant and harvest for your area.


Ornamental alliums often have a light lilac fragrance. Very tall cultivars may need staking to keep them upright. Lavender, purple, pink and white are the most common flower colours.


When using ornamental alliums as cut flowers, make a clean cut with a sharp knife or razor blade when less than half of the florets are open. As the flowers fade in the garden, trim them off with scissors or secateurs.


Ornamental alliums have few pest problems. Avoid very tall varieties in windy areas.

Planting and Harvesting Calendar

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Pests which Affect Allium (Ornamental)

Plant Diseases which Affect Allium (Ornamental)