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Growing Onion

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

(Best months for growing Onion in New Zealand - cool/mountain regions)

S = Plant undercover in seed trays T = Plant out (transplant) seedlings 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
    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

11 Apr 17, nik (New Zealand - temperate climate)
I planted 50 red onion seedling last year and they all split into 3 or 4 more like shallots, so after 6 months I gave up and pulled them out What went wrong ? there is no red shallot variety is there?
11 Apr 17, John (Australia - sub-tropical climate)
Onions are like daffodils and other bulbs in that they will grow extra bulbs as a form of multiplication. This can be caused by planting at the wrong time of the year for the variety. Check this on the seed packet and plant accordingly. Sadly nurseries sometimes sell 'out of season 'plants that look good. Tomatoes are a classic example with many plants sold after a few sunny days in late Winter or Early Spring. Trust this helps.
07 Jan 17, john timea (New Zealand - sub-tropical climate)
Hello my name is john timea .I am from Papua new guinea highlands and iam interested in growing blub brown onion.please advise what variety will I grow.thank you. john timea.
09 Jan 17, John (Australia - temperate climate)
It would take a lot of time to cover onion grwing in New Guinea. I suggest you Google 'onion growing in New Guinea as there is some quite good articles. Bulb onions grow well in the lowland areas but fungal problems are a consideratio everywhere. These articles may give you some clues as to what varieties to grow. Trust this helps.
25 May 16, Colin Campbell (New Zealand - temperate climate)
I planted onion seedlings 2 months ago. They all look healthy but I am concerned at the length of the tops--up to 30cm--which is causing some lifting of the bulb. Should I trim the tops back or leave as is? Your advice would be appreciated. Thank you.
05 Nov 11, wes (New Zealand - sub-tropical climate)
We grew white onoins & have just harvested & are now drying in the sun. How long should they be dried ? Is it better to leave the tops on or should they be cut off to speed drying? Regards,wes.

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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. GardenGrow 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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