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Growing Onion

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

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

S = Plant undercover in seed trays. T = Plant out (transplant) seedlings. P = Plant in the garden.

  • 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
    Red onion
  • Young brown 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

15 Jan 17, PAUL DZIADULEWICZ (Australia - temperate climate)
BROWN ONIONS GROWN IN OUR VEG PATCH HAVE NO TASTE AT ALL. THEY LOOK GREAT, ARE A GOOD SIZE AND APPEAR TO BE HEALTHY CAN YOU OFFER ANY SUGGESTIONS? CHEERS PAUL
16 Jan 17, John Mauger (Australia - temperate climate)
Hello Paul. There could be a number of reasons for your problem. 1. Are the onions ripe? When onions are ready for harvest the tops will have died off and will be lying flat on the ground. 2. Were they 'salad' or 'long keeping' onions? Salad onions are flat and very mild flavoured. What was the variety and its description? Brown or White Spanish onions are much hotter than mild varieties such as' Creamgold' or' Pukekohe'. This may not solve the problem for your current crop but trust it will give you some answers for the next one.
02 Jan 17, Bob (Australia - temperate climate)
I'm in Sydney NSW, and I think I'm in the temperate zone. is that correct Cheers
03 Jan 17, John Mauger (Australia - temperate climate)
Sydney would be temperate but you can grow a lot of subtropical things there as well. A lot of Sydney does not get frosts.
10 Dec 16, John (Australia - temperate climate)
I would like to grow some red onions I can not find seeds but I brought some bulbs from the local green grocer now do I plant the bulb in the garden or do I keep them in the cupboard or fridge till they spout I live in Tasmania
10 Dec 16, John (Australia - temperate climate)
Onions are biennial; that is, they grow and die down the first year then sprout again and flower in the second year. I would plant the bulbs as they will grow and flower this season giving you an abundance of seed. There is a seed company called The Lost Seed in Tasmania and there was another called Phoenix Seeds, if you googled them I am fairly sure one of them would have red onion seed. Trust this helps.
29 Nov 16, linda davies (Australia - temperate climate)
my onions are very big and some are going to seed. Should I leave them to dye back or pull them and leave on racks to dry.
29 Nov 16, John (Australia - temperate climate)
Normally onions go to seed in their second year. You could bend the stems at bulb level so they are basically crushed and lying flat. this will trigger ripening snd when the the top dies off you will be right to harvest and store them. Yhis has worked for me and I've heard it talked about by other gardeners.
15 Nov 16, Bob (Australia - temperate climate)
I planted white onions seedlings (variety unknown) in mid-June with the usual expectation that they would be ready for harvest in early December; when the tops usually start to dry out. This year about 50% of the plants have started to produce flower buds in early November. I suspect that if I allow them to flower; the quality and storage-life of the onions will be reduced. Should I harvest them before the first flowers blossom? Regards Bob.
18 Nov 16, John (Australia - temperate climate)
Onions are biennial, that is they grow and die down in he first year then regrow and flower/seed in the second year. If seedlings of biennials are stressed in the punnets before they are planted or if the variety is not suitable for planting at the time of the year the plants may be triggered to flower and set seed. If you leave them they will increase like daffodil bulbs.
Showing 1 - 10 of 102 comments

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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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