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Growing Onion

(Allium cepa)

Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
  S   T P S   T        

(Best months for planting Onion in Australia - sub-tropical regions)

S = Plant undercover in seed trays. T = Plant out (transplant) seedlings. P = Plant direct in garden where they are to grow.


  • 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 in same bed): Lemon Balm, Borage, Carrots, Beets, Silverbeet, Lettuce, Amaranth
  • Avoid growing in same bed: 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

02 Jul 14, coralie (Australia - temperate climate)
Having trouble purchasing tree onions/Egyptian running onions. Can you help
26 Jun 14, peter mallon (Australia - temperate climate)
looking to grow some pickling onions.should i use seed or are they availabli in seedlings
18 Jun 14, Jo Dumergue (Australia - temperate climate)
I planted out my white & red onion seedlings; my leeks & spring onions over 6 weeks ago. None have done well, and became infested with tiny black bugs. I sprayed with soapy spray and sprinkled ash from the fire over them - but I think I've lost them all. What could these bugs be - look a bit like aphids.......and very disappointing as the onions seem to take ages to grow.
01 Jul 14, Barb (Australia - temperate climate)
Hi Jo, Sounds like black aphids. I plant a heap of flowers in the vegie garden to encourage predatory insects that eat aphids. But if you have so many aphids, it might be that the plants are unhealthy, which means the soil might not be good. I'd be inclined to add some good compost to the soil (well matured for onions) and also foliar feed the onions with a liquid seaweed such as seasol to help make the onion plants more resilient. Also good to interplant them between lettuce as this seems to help hide the onions from the bugs while they're young and vulnerable.
29 May 14, (Australia - temperate climate)
I have just bought 1 kg of onion seed and may not use all of it this year, will the seeds still be good to use in a year's time? Thanks
20 May 14, Maurice (Australia - sub-tropical climate)
There are a few perennial varieties of onion around so you do not need to mess around with saving seed and planting seedlings each year. They are hard to find but easy to grow, they seem to grow well even here in the tropics. I am very happy with mine, I got them from living-mudflower.blogspot.com.au/2013/05/perennial-annual-vegetables-for-sale.html
03 May 14, Robin schuboxey (Canada - Zone 2a Sub-Arctic climate)
I reccommend you grow your Australian onions in seed trays before you plant them in the garden. It works here in Canada at minus zero so it surely must work in your warm Australian soil
05 Apr 14, Dave (Australia - sub-tropical climate)
My onions are growing ok but they are all lying down instead of standing up. Is there something I should be doing to make them stand up?
22 Feb 14, Ali (Australia - temperate climate)
I am still drying out on onions I have taken it the top the the onion(where all the seeds are) but they are still green. What do I do? When do I plant them? Would they turn out okay!!?
10 Feb 14, kathleen harris (Australia - temperate climate)
Can you recommend a variety of onion that I can grow for pickling. The pickling onions in the shops are too big and not nearly crisp enough.
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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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