When to Plant Onion in Melbourne, Cool Temperate Guide

Sow March to September. Right now in October it is out of season. The next sowing month is March.

Also called spring onion, scallion, shallot (the Australian name for spring onion).

Planting window
Sow early types in March to April and long-day types such as Brown Spanish in June to August. Bulbs take six to eight months and are lifted...
Days to harvest
about 13 weeks
Sunlight
Full sun (minimum 6 hours direct)
Water needs
Consistent moisture during bulb development. Water deeply once or twice weekly. Reduce...
Spacing
12cm apart, 30cm between rows
Soil pH
6.0-7.0
Shop price
$2.66/kg average

Published · Last reviewed · By GardenBuddy.au
Growing advice is reviewed by hand. Planting dates, current conditions and prices on this page update daily.

This Onion guide is written for the Cool Temperate zone, which takes in Melbourne, Hobart and Geelong. Somewhere else? Your postcode picks the right one.

Not your zone? Cairns Brisbane Sydney Canberra Alice Springs Perth

Also handy: will it frost this week? and what grows in shade.

Onion

Photo: Wikimedia Commons

Onions are a staple in Australian kitchens and one of the most widely grown alliums in home gardens. Bulb formation is triggered by day length, making variety selection critical based on latitude. Short-day types suit northern Australia, while long-day types perform best in southern regions.

See what grows now in your own postcode

Planting Calendar for Cool Temperate

Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
- - S/D S/D S/T/D S/T/D S/T/D T/D T - - -

S = Seed Tray   T = Transplant   D = Direct Sow

Want a nudge when it is Onion sowing time in Melbourne?

One email a week with what is worth planting in the Cool Temperate zone right now, Onion included, plus which veg has jumped in price at the supermarket. Free, and you can stop it in one click.

Current Growing Conditions

Soil temperature: 14.9°C (optimal range: 8–30°C) ✓ Ready to plant

Modelled from Open-Meteo forecast (Melbourne), not a live sensor.

What this month normally looks like

In October the Cool Temperate zone normally runs 19°C by day and 8°C overnight, with about 67 mm of rain over 9 or 10 wet days. The coldest October night on record across the zone was -3.0°C, so a late frost is not out of the question. Averages 1991 to 2026, 28 postcodes, SILO.

How to Grow Onion in Cool Temperate Australia

When to Plant

Sow early types in March to April and long-day types such as Brown Spanish in June to August. Bulbs take six to eight months and are lifted when the tops fall over.

Soil
Well-drained, fertile loam enriched with compost. Avoid heavy clay or freshly manured soil which causes forking and soft bulbs.
pH Range
6.0-7.0
Sunlight
Full sun (minimum 6 hours direct)
Spacing
12cm apart, 30cm between rows
Watering
Consistent moisture during bulb development. Water deeply once or twice weekly. Reduce watering as tops begin to fall over (curing signal). Overhead irrigation can reduce thrips but increases fungal...

Companion plants: Carrot, Beetroot, Lettuce, Chamomile, Strawberry

Avoid planting near: Beans, Peas, Asparagus, Sage

Grow before, grow after

Onion belongs with the alliums, the roots and alliums turn of a four turn bed rotation.

Grow before it
Fruiting crops (Tomato, Capsicum, Zucchini)
Grow after it
Legumes (Beans - Dwarf, Peas, Broad Beans)

Give the bed 3 turns before alliums go back in. Onion, garlic and leek like a lean bed and clean up after the heavy feeders.

Cool Temperate Growing Tips for Onion

Recommended Varieties

  • Pukekohe Long Keeper (long-day)
  • Creamgold (intermediate)
  • Brown Spanish
  • Ailsa Craig (long-day)
  • Red Globe

Key Challenges

  • White rot is a serious and persistent problem
  • Downy mildew in cool, damp winters
  • Onion maggot damage to spring plantings

Pro Tips

  • Long-day varieties produce the largest bulbs in Melbourne's latitude
  • Use insect netting to exclude onion fly from spring plantings
  • White rot: if you have it, consider growing in containers with fresh soil

Harvesting Onion

When ready: Tops fall over naturally and begin to yellow. Bulb skin is papery and dry. Neck tissue is thin and soft. Do not push tops over prematurely as this reduces storage life.

How to harvest: Loosen soil with a fork and lift gently. Do not pull by the tops. Lay on their side in the garden for 1-2 days if weather is dry, then move to a well-ventilated, shaded area for 2-4 weeks to cure fully. Roots and tops are trimmed after curing.

Worth growing?

A 2.4 m × 1.2 m bed fits 72 plants, about $29 worth at today’s Aldi, Coles and Woolworths prices, checked on 5 October.

That is roughly 11 kg at $2.66 a kilo.

Draw your onion bed → No account needed.

Where to next

What onion costs in the shops right now, retailer by retailer, updated daily.

Also worth sowing in the cool temperate zone this October: Radish, Sweet Corn, Beetroot and Chilli Peppers.

The pest most likely to find your onion: Thrips (Onion, Tomato, Western Flower).

Supermarket Price

Current average retail: $2.66/kg (12-month range: $1.99–$5.20)

Grow your own and save on grocery bills.

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Common Questions About Onion

When do you plant onion in Australia?

It depends on your climate zone, not the calendar month alone. Planting months by zone:

Does onion grow all year round in Melbourne?

No. In the Cool Temperate zone the planting months are Mar to Sep. Outside that window it either bolts, sulks or gets cut down by the weather.

What else is onion called?

Onion is the usual Australian name. Overseas seed packets and recipes call it spring onion, scallion, shallot (the Australian name for spring onion). Same plant, same growing advice.

Which zone am I in?

Type your postcode into the box under the heading and the page tells you, and links this crop in your own zone if it differs. Or look it up on the grow zone map. This page is the Cool Temperate zone, Melbourne is its reference city.