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Common Garden/Globe Onion: How to Grow – Vegetable of the Month

Onion stats/requirements at a glance

Ease of Raising:
5/5 – Very easy (plant and leave)
1-2/5 – Weekly to twice weekly
4/5 – Full sun & shade tolerant
1/5 – None
4/5 – Every two weeks
Time to Harvest:
5/5 – Forever (+5 months)
Frost Hardiness:
4/4 – Very Hardy (can’t take black frost)
Culinary, pest control, beneficial insect attracting
Most Problematic Nemesis:
Usually pest free, some problems with onion fly & rotting
Container Plant:
Most definitely
Common garden globe onion
Allium cepa var cepa 
Herb Book (1914) Panel 9 
Kurt Stuber Online Library
Common garden globe onion
Allium cepa var cepa
Herb Book (1914) Panel 9
Kurt Stuber Online Library

Quick Intro

Onions are very easy to grow, but take a long time to mature. They virtually have no nutritional value and are mostly used to add flavour to meals. Planted between other vegetables, they act as pest deterrent, especially for aphids – but beware an ailing onion is just as likely to attract aphids!


The origin of the onion is obscure, but historians agree that it has been cultivated since ancient times. Although some wild relatives are found in Central Asia, taxonomists believe these to be ‘feral derivatives’ of the cultivated crops. The Romans transported the onion throughout Europe, whereas Columbus took the onion across the seas to America. The ancient Egyptians were known to place onions in the eye sockets of mummies before burial as the onion’s rings represented eternal life.

Science Stuff

The common or bulb onion, Allium cepa, belongs to the Amaryllidaceae family which includes several showy flowering bulbs such as the amaryllis lilies, agapanthus and daffodils.

The common onions have two groups, specifically:

  • Allium cepa var. cepa = the onions we all know, large single fleshy spherical bulb
  • Allium cepa var. aggregatum = shallots and potato onions.

Common onions come in a variety of colours, shapes and sizes making for interesting additions to food dishes.

Common garden globe onion cultivars
Allium cepa var cepa White Red Shallot Garlic
Common garden globe onion cultivars, picture includes shallot and garlic relatives
Allium cepa var cepa 

Growing Onions

Common onions are very easy to grow, but to require a large amount of patience as they take 6-8 months to mature. They prefer hot and dry climates, therefore watering should be kept to a minimum especially in winter, whereas in very hot weather – a watering twice weekly should be ample.

Common garden globe onion Seedlings
Allium cepa var cepa
Common garden globe onion Seedlings
Allium cepa var cepa

Onions are easily raised from shallow planted seed or alternatively from onion sets (small immature bulbs). Seedlings will require a bit more frequent watering until they become established. It is best to start onion seeds during the autumn months (March/April), since during the winter a large amount of garden space is available for the long-standing onions. This also allows the onions to grow whist daylight hours are at minimum and when spring/summer arrives, the longer daylight hours stimulate bulb development (at which time a little added potassium will assist with bulb swelling). Bulbs start to mature once the leaves bend over, then arrange the leaves to allow maximum sunlight exposure for each bulb to aid the maturing process.

Other Onion Tips

  • Onion beds require regular weeding.
  • Once the foliage falls over, expose a bit of the bulb to the sunlight by brushing off some soil to assist with the maturation process.
  • Mature bulbs have a good papery layer around them and non-green flesh.
Common garden globe onion 
Allium cepa var cepa
Common garden globe onion
Allium cepa var cepa 

Harvesting & Storing

Bulbs are ready to harvest two weeks after the leaves fall over or when the leaves turn brown. Correct bulb storage is of the utmost importance as we lost an entire harvest due to rotting bulbs! Bulbs should preferably be strung up either by braiding their foliage, tied and hung up with string or hung up in stockings/net bags – a lot of air should be allowed to flow around the bulbs to ensure they do not rot. Fresh onions should keep for up to a month in a cool, dark place – if longer storage is required it is best to leave them in the soil and harvest as required.

Common garden globe onion drying braids
Allium cepa var cepa
Common garden globe onion drying braids
Allium cepa var cepa 

Seed Collection & Storage

Onions flower in their second summer after exposure to cold winter temperatures. Some rogue onions may bolt before this and seed should not be saved from these. Onions have light purple or white perfect umbels that are insect pollinated. Although, they are good at attracting many beneficial insects, such as bees, bumble bees and hover flies, chives would be more suited to plant for this purpose. Common onions will cross-pollinate with other cultivars as well as spring onions, but will not cross with leeks or chives.

Common garden globe onion flowers white
Allium cepa var cepa
Common garden globe onion flowers white
Allium cepa var cepa 

Carefully remove the dried umbel stalk and shake off any seeds through a sieve or rinse quickly with water (viable seeds will sink, all other materials will float). If the stalks require further drying, place them in a brown paper bag – this will also catch any falling seeds.

Onion seeds do not keep well, only 1-2 years so it is best to use them up every season and save new seeds every year (from two year old onions). The optimum germination temperature is 10 to 35oC (50-95oF).

My Onions:

Starke Ayres Red creole: Medium sized red onion with a mild flavour. Quicker to mature than the larger white ones.

Common garden globe onion flowers purple
Allium cepa var cepa
Common garden globe onion flowers purple
Allium cepa var cepa 

3 thoughts on “Common Garden/Globe Onion: How to Grow – Vegetable of the Month

    1. Wow, I didn’t know that they do that! They must be desperate for food, the August Moon is known as the Hunger Moon after all… but that does explain why I’ve also had onion seedlings one moment and the next day their gone!


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