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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

14 Oct 14, Ralph (Australia - temperate climate)
I put a whole red onion into my "garden" about 2mths ago. Now have 5 long stems with what look like flower buds and grass like foliage. Do I separate the stems and replant? Any advice greatly appreciated.
27 Sep 14, Deeanna (Australia - temperate climate)
I am a new gardener but I have to live with possums, bush turkeys, mice and wallabies. It has been my experience over the last 4 years that both possums and wallabies would be the culprit eating your onion tips. We cover ours with bird netting. This leaves us with the wallabies that push against the netting to nibble. But they do not get to eat much once the garden is covered securely.
21 Sep 14, Sarina (Australia - temperate climate)
Our onions (brown and red) are hanging on the fence in a planter box we made from pallets(we have a dog who likes to knock things over). However something is eating the tips of the leaves and only the tips. It wouldn't be possums as the dog would be going crazy. There is no bugs at all near the plants. The fence is colourbond steel, in off-white, and we can not see any trails, marks, tell tale signs of any slugs or snails etc. there is no bugs or sign of them in or around the pallets, and the boxes are lined with weed mat to stop the dirt from falling out. Any ideas of what this could be that's loving the tops of the onions? It's our first ever attempt at growing veggies, and we would really like some to survive!
09 Dec 14, Glen (Australia - sub-tropical climate)
Sounds to me like heat transfer from the tin fence. Regards
31 Aug 14, Suzanne (Australia - temperate climate)
Do I let the seed stem of the onion grow or cut it off Onions looked good till the seed stem grew and then they just went hard inside
18 Aug 14, Rob (Australia - temperate climate)
Hello can i purchase walking onion or egyptian onion in melbourne or sydney
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.
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