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A picture of a Onion


Allium cepa

Also known as

Garden Onion, Shallot, Bulb onion, Common onion

Photo by Going.Local (All rights reserved)

Full Sun
Easy care
Moderate watering
Frost Hardy


RHS hardiness


Minimum temperature

Expected size








2 years to reach maturity


  • spring
  • summer
  • autumn
  • winter

This plant has a strong fragrance

More images of Onion

A photo of Onion
A photo of Onion
A photo of Onion
A photo of Onion

Onion Overview

The Common Onion is grown as an annual but will actually live for 2 years and produce a large pompom-like flower which can have some ornamental value in a cottage garden display. Also grown for the bulb, which is eaten as a vegetable for over 4000 years. It can be used raw in sandwiches and salads as well as being added to many different types of cooked dish.

Common problems with Onion

Onion Companion Plants

How to harvest Onion

When the tops turn yellow and "wilt", it is time to harvest; usually between 100 and 120 days after planting. Gently lift the bulbs before the foliage has fully died back, place the whole plant on racks with good ventilation in full sun to dry out for 2 weeks before being stored in a cool dry location.

How to propagate Onion


Plant onion sets 10cm from mid-March to mid-April. Plant the bulb in the soil with just the tip showing, and firm the soil around them. Birds can be a problem, pulling new sets from the ground so cover with a fleece until firmly rooted.


Direct sowing in late autumn in a well-prepared bed and thin out later. Will require about 9 to 12 hours of daylight to stimulate bulb formation.

Special features of Onion

Repels harmful insects

The juice is used as a moth repellent. Rubbed into the skin it acts as an insect repellant.

Attracts bees

Only when in flower which is in its second year of growth.

Crop rotation

Onions are light feeders. Plant these after heavy feeders. Follow these crops with legumes.

Other uses of Onion

Culinary, vegetable. Can be grown in containers.


When eaten raw, onions benefit the health in many ways, i.a. anti-inflammatory, antiseptic, prevents tooth decay. The juice is a first-aid treatment for bee stings and quickens healing of wounds.


Although the bulbs are probably the base ingredient of the vast majority of cooked dishes the world over, the flowers are also edible.

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