Growing Onion

Jan F M A M J J A S O N Dec
  P P T                

(Best months for growing Onion in South Africa - Summer rainfall regions)

S = Plant undercover in seed trays T = Plant out (transplant) seedlings

  • Easy to grow. Grow in seed trays, and plant out in 4-6 weeks. Sow seed at a depth approximately three times the diameter of the seed. Best planted at soil temperatures between 8°C and 30°C. (Show °F/in)
  • Space plants: 5 - 10 cm apart
  • Harvest in 25-34 weeks. Allow onions to dry before storing.
  • Compatible with (can grow beside): Lemon Balm, Borage, Carrots, Beets, Silverbeet, Lettuce, Amaranth
  • Avoid growing close to: Peas, Beans
  • Red onion
  • Young brown onion

Onions come in a range of colours and shapes and sizes. Brown :- strong flavour and pungent. Usually good keepers for storage. White :- milder but still flavoursome. Keep fairly well. Red :- Mild, suitable to use raw in salads and sandwiches. The seedlings should be allowed to gain a bit of strength before planting out - usually 4 to 6 weeks will be enough. When they are big enough to handle, you can plant out. They start off looking like blades of grass.

They don't have to be in a greenhouse (though that would be ideal), any sheltered spot will do. The idea is to guard against rapid changes of temperature, especially at night.

Onions can be bought as young plants (sets or seedlings) from garden shops/nurseries to plant straight into garden beds. Choose your variety according to your climate and the time of year as some onions will grow better in the cooler months .

Onion bulbs should sit on the surface of the soil. Do not cover. They will take six to eight months to mature. Onions are ready when the tops start to dry and fall over. Pull them and leave to dry for a few days. Store in a cool, dry airy place. Use a net bag or make a string by weaving the tops together.

Culinary hints - cooking and eating Onion

Brown onions roasted whole with other vegetables are delicious.
Red onions add colour to salads or stir-fry.

Your comments and tips

24 Jun 20, Jimmy Spear (South Africa - Humid sub-tropical climate)
I planted half of an onion In a pot under potting soil +- 4 weeks ago and it has grown 3 healthy shoots about 20 cm long. What must I do now?? Please advise
25 Jun 20, (South Africa - Summer rainfall climate)
Keep growing it and see what happens.
25 May 20, Mlungisi Zwane (South Africa - Summer rainfall climate)
when is the good time/season to plant onion in south africa?
25 May 20, Liz (New Zealand - temperate climate)
Have a look at this page
11 May 20, Caswell Tlali (South Africa - Summer rainfall climate)
What will happen to my onion if I plant it in August in Lesotho (particularly along Caledon)? I am in Berea district in Lesotho. My fields are on the bank of Caledon River.
22 May 20, Anonymous (South Africa - Summer rainfall climate)
Gardenate suggests you plant Feb to April. Try planting it in August and it probably won't even germinate. Most plants have a defined time of the year to grow in a particular climate zone.
12 May 20, Anon (South Africa - Semi-arid climate)
Check the top of the page .
10 Aug 19, Sam (South Africa - Summer rainfall climate)
I just planted onions that got spoiled and started to grow but now each bulb has grown into a set of seedlings. Do I pull them out and plant them separately or leave them grow as they are? Kind Regards Sam
13 Nov 19, anon (South Africa - Summer rainfall climate)
Pull apart.
13 Jul 20, Elizabeth (South Africa - Summer rainfall climate)
Leave them to grow. Pulling apart will break the roots. A group of onions bulbs will develop and you can harvest them together or one at a time by twisting one gently.
Showing 1 - 10 of 53 comments

I just planted onions that got spoiled and started to grow but now each bulb has grown into a set of seedlings. Do I pull them out and plant them separately or leave them grow as they are? Kind Regards Sam

- Sam

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This planting guide is a general reference intended for home gardeners. We recommend that you take into account your local conditions in making planting decisions. Gardenate is not a farming or commercial advisory service. For specific advice, please contact your local plant suppliers, gardening groups, or agricultural department. The information on this site is presented in good faith, but we take no responsibility as to the accuracy of the information provided.
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