Growing Onion

Allium cepa : Amaryllidaceae / the onion family

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

07 Feb 24, Brenda (USA - Zone 5a climate)
What do you mean when you say plant out
07 Feb 24, (USA - Zone 5a climate)
Hi, it means to take the seedlings you've grown from seed, and plant them in the ground or bigger pots.
08 Feb 24, (USA - Zone 5a climate)
Thanks
26 Dec 23, alfred rockhold (USA - Zone 6a climate)
i live in wv
01 Mar 23, Susan (USA - Zone 6b climate)
Can I direct sow intermediate onion seeds in fall in a raised garden bed covered with leaves and over winter them. Zone 6b
29 Jan 23, Gladis (USA - Zone 10a climate)
What variety grows best in zone 10a (Southern California)?
07 Jan 24, Lisa (USA - Zone 10a climate)
Any Short Day onions. Google "Short Day Onions". I also live in Southern California and just received my onions sets from Dixondale Farms.
29 Jan 23, Ron Holt (USA - Zone 7b climate)
I would like to grow onions (sets) in my garden this Feb. 23 to be harvested as mature onions in about 6 months. I would prefer sweet onions. Can you suggest a a particular type ? Do I need to buy heated onions? Thanks, Ron
19 Jan 23, Sharon Burke (USA - Zone 7b climate)
I took a kitchen scrap from a yellow onion and now I have roots what kind of soil should I plant this in for indoor in January please and thank you
24 Sep 22, digna carwell (USA - Zone 10a climate)
Hello I lived in 10A zone I would like to know when is the best time to grow , onions , garlic, carrots and mist vegetables? Thank you in advance for your response.
Showing 1 - 10 of 35 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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