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

Your comments and tips

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16 Mar 21, David (South Africa - Summer rainfall climate)
I just transplanted some onion seedlings into a garden bed and it is March. Will they develop normally despite being planted early?
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17 Mar 21, (South Africa - Summer rainfall climate)
You should be ok. Good idea to check planting times before buying/planting seeds or seedlings. You also have to consider your local conditions.
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28 Feb 21, Barbara Esparza (USA - Zone 9b climate)
Are there any onion sets that I can plant in Texas zone 9b that are more heat resistant?
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02 Mar 21, Anonymous (Australia - sub-tropical climate)
Plants generally have a temperature range that they grow in. That is why most crops are seasonal in a district. Try planting out of that range and you could fail.
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22 Feb 21, Brett (Australia - sub-tropical climate)
If I was to plant brown onions, once harvested, how long will they last when they are stored in the pantry?
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05 Mar 21, (Australia - sub-tropical climate)
Brown onions keep better than white onions. Let them harden off a bit after picking and keep in a cool aeriated area. Don't pack them tight - like in a bag.
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26 Feb 21, Greg J (Australia - temperate climate)
Geelong Australia. I pulled up a couple of beds of brown onions in November. They've been hanging in the back shed since then, no problems at all. They're still as good as when I pulled them up, and we've been using them slowly. I think they will easily last 6 months or more.]
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25 Feb 21, Brad (Australia - sub-tropical climate)
Depends on the variety of brown onion mate, the more pungent ones will store longer but they are more suitable to cooler areas. I'm sub-tropical too i'm from brisbane and I do a variety call "Texas early granno" I pulled about 70 to 80 out last year and none went bad. The trick is to harvest them when you need them. Green Harvest is a great site where I get most of my seeds from they are situated in south-east Qld and they have a lot of info of different varieties and the climates they are best suited for. Hope that helped Brett. -Brad
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16 Feb 21, Judith c Greenleaf (USA - Zone 9b climate)
Can I plant onion sets in February or march? what sweet onion varieties do you suggest for No. Ca. marine zone 9B? Thank you.
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17 Feb 21, Anonymous (USA - Zone 9b climate)
Consult the planting guide calendar and the footnote at the bottom of the page. If it says plant April and you plant Feb, the seeds/sets probably won't germinate/survive . There are reasons why it says to wait until April but take local conditions into considerations.
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Showing 101 - 110 of 378 comments
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Absolutely! We do all the time! We always cut the onions we buy horizontally in half when cooking and carefully peel down to the middle chunks where you can see how many "dots" are gonna be onions next year. We have a big patch of sandy loose soil that has a lot of chicken manure and/or compost here or there that we plant all of them in. We plant them an inch or so under the soil (totally covered up is best but not too deep) and we do not break them apart first. They grow into BIG beautiful onions in a year or so if you give 'em a drink of water when its dry for weeks. AND they make seeds too! Good seeds if you let them dry all the way out! We love getting free food from cooking scraps... with a bit of pre-planning on slicing the onions right to begin with... Try replanting carrot tops if you want fresh seeds... the top 2" of a regular carrot grows into fluffy foliage and sends up nice fresh seed heads in late summer. Freebies are fun!

- Melinda Schwab

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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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