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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
    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

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?
23 Mar 18, Fanie Zulu (South Africa - Summer rainfall climate)
Good day, can I plant the Australian brown onion throughout the year in South Africa? I want to maintain the monthly supply for my customers.
23 Apr 18, hennie (South Africa - Summer rainfall climate)
typically root vegetables such as onions,carrots and beetroot can be grown year round , just ensure they have enough deep soil , and keep an eye on the moisture levels, after the bulbs started forming , and give them ample space between each plant , thinning is an essential function.
12 Mar 18, Albert (Australia - temperate climate)
When do l plant a giant decorative allium and how deep.? any other advice would be appreciated.
13 Mar 18, Mike (Australia - tropical climate)
Type into google
10 Mar 18, Nana (South Africa - Summer rainfall climate)
I live in Lady Frere, Eastern Cape S.A. I would like to know if I can plant onions now in March. Also how long will they take to mature.
02 Mar 18, Leigh (New Zealand - temperate climate)
Hi, I’m having fun growing potatoes, Kumara and even sweetcorn that have sprouted in the bottom of my pantry. Wondering if the same should work with a brown onion that has sprouted greens out of the top?
22 Feb 18, Trevor Smith (New Zealand - temperate climate)
If I was to sow seeds in February and plant out in say May would frosts have any adverse effect on them?
26 Feb 18, Mike (New Zealand - temperate climate)
If you sow now you would transplant in 6-8 weeks. I think onions can handle some frost. Check on the net about this.
17 Jan 18, Joe Branco (Australia - temperate climate)
Why are brown and white onions sown at different times
Showing 1 - 10 of 194 comments

Do I have to roll the leaves of the plants to enhance bulb forming at this time before they are harvested to prevent new growth?

- Danie

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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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