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Growing Onion

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

(Best months for growing Onion in USA - Zone 5a regions)

S = Plant undercover in seed trays P = Sow seed

  • 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 46°F and 86°F. (Show °C/cm)
  • Space plants: 2 - 4 inches 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

12 Nov 18, John (New Zealand - temperate climate)
My onions growing in Napier are sprouting seed heads. Some are large seeming perhaps fully grown or close but some aren�t. Should I nip the heads and leave them or pull them immediately?
11 Nov 18, Phil (Australia - temperate climate)
I usually grow brown onions which store well, however as we were running out I planted white ones as you can plant them earlier in the season. Now I have heaps of good sized white onions which have just started to run to seed, does anyone have good ideas on how to store them longer than a few weeks?
24 Oct 18, Michael Jones (Australia - temperate climate)
when do i plant cipollini onion seeds in west Australia
25 Oct 18, Mike (Australia - sub-tropical climate)
Read the guide here. Plant first half of the year - probably after Feb - summer probably too hot.
18 Oct 18, Malcolm Langley (Australia - sub-tropical climate)
I planted onions last season and thined out where necessary and had a reasonable crop.this season l did it a bit differently. I planted the seeds into pots and then replanted into the ground so that I didn't waste any by thinning out. The seeds used were the from the same suppliers and were brown onions as before. This season they are growing well but most of them have very thick stems and seed pods are formed. The onionbulb in lots of instances is not developing .am l doing something wrong? Mal.
23 Oct 18, Mike (Australia - temperate climate)
I had this problem this year. First time I had grown onions. I put it down to too rich a soil. Maybe less N applied. And probably back off the watering a bit when they have grown for say 4 mths.
06 Oct 18, Wayne (Australia - temperate climate)
Onion Red Odourless: Planted sixty seedlings in April which have been growing well but are now going to flower and bulbs have not formed. (Adelaide Hills)
07 Oct 18, Mike (Australia - sub-tropical climate)
I grew onions for the first time this year. Mixed success. White ones. Some formed bulbs some didn't - good health plants - probably too much N. Onions can take 6-8 mths to grow.
09 Sep 18, Sally (South Africa - Summer rainfall climate)
Which varieties of onion can I plant in Johannesburg now. From seed
02 May 18, TJ Russell-Zapata (USA - Zone 7a climate)
I am moving to zone 7a from Texas. Do I still over winter garlic and onions?
Showing 1 - 10 of 205 comments

Pick them and then leave in the sun for a few days to brown off.

- Mike

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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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