Growing Onion

Allium cepa : Amaryllidaceae / the onion family

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

(Best months for growing Onion in USA - Zone 7b regions)

  • 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 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 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

Post a comment or question Display Newest first | Oldest first, Show comments for USA | for all countries
05 Nov 24, (South Africa - Summer rainfall climate)
Can I start sowing onion seeds in November. If so which type of onion is suitable
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08 Nov 24, Celeste Archer (Australia - temperate climate)
One last thought .... I never seem to get everything into my first response ==> Egyptian walking onion --onions and other alliums need more phosphorus and potassium than most other vegetables. They also need more copper, manganese, zinc, and molybdenum- however most of these are adequately represent in compost. BUT, if you have any issues, and it is unlikely that you will with walking onions --- but if you do, first thing I would do is ensure all of these elements are present (in Canada our "old" pennies have a lot of copper, we just add this obsolete currency to the garden). Molybdenum is found in wood ash (just the stuff from the fireplace, firepit or wood burning stove -- provided you have burned "clean wood" )-- probably lots in leaf compost, and banana peel compost)-- of course potassium in potash etc.
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08 Nov 24, Celeste Archer (Canada - Zone 7b Mild Temperate climate)
Tree onion (Allium x proliferum) also known as Walking Onions, Egyptian Onions, Topset Onions are a perennial onion. They are part of the Alliaceae or onion family and is a hybrid of the common onion (Allium cepa) and the welsh onion (Allium fistulosum). Tree onions are the easiest of the onions to grow coping with 40-degree heat and frosts. Check out his video -- https://www.youtube.com/watch?v=olOrA80C40s -- variety matters -- and DURATION in the soil -- my understanding is harvesting too early results in low yields -- so wait for the 3rd set of topsets before harvesting as per the video. These onions take longer to get going, but are very reliable and topsets, mean you can always propagate (which is a nice to have -- since future generations get stronger and better suited to your climate).
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24 Oct 24, ESTHER C BROWN (USA - Zone 7b climate)
CAN I PLANT ONION SEEDS NOW/ OCTOBER IN A 4X4 GARDEN BOX TO OVER WINTER/ ZONE 7B NY
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20 Jun 24, Nicole Hofstetter (USA - Zone 7a climate)
I wanted to try to grow big texas sweet onions Can I grow them in a container (1 plant in a container) ?
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23 Jun 24, (USA - Zone 9a climate)
Should be ok. Would probably need 1 sq ft per onion plant.
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12 Jun 24, Portia (South Africa - Summer rainfall climate)
Can I plant onions in south Africa September month. I'm mpumalanga lowveld nelspruit.
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02 Jun 24, Karen Ventura (USA - Zone 8a climate)
what type of onions should be planted in zone 8, ie: long day, short day etc?
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27 Jun 24, Laura L Ellington (USA - Zone 8a climate)
in Zone 8 intermediate and sort day onions can be grown along with bunching green salad onions.
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05 Apr 24, Cami (USA - Zone 9b climate)
any advice on best onion variety for zone 9b? I have tried texas grano but have not seen results yet (2 weeks and counting...). I live in southern california
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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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