How to Grow Onion in Australia
A cool-season root crop for the home garden
Growing your own Onion is one of the more satisfying things you can do in an Australian backyard. It is rated intermediate to grow. Saves ~$2-5/week, a staple in nearly every meal.
This guide covers when to plant Onion in your region, the position and soil it likes, how to sow and space it, day-to-day care, the pests and diseases to watch, and how to harvest and store your crop.
When to Plant in Your Region
Onion is a cool-season crop, half-hardy (it takes light frost but not a hard freeze). In subtropical South-East Queensland it is sown in March, April, May and June. Timing shifts with your climate, so choose your region below for a local calendar.
Varieties to Try
Early Cream Gold
Short-day brown onion bred for QLD. The commercial SEQ standard. Reliable, stores well.
Try: Yates, Mr Fothergill's, Bunnings
Red Tropicana
Short-day red onion. Mild, sweet, excellent raw in salads. Bred for subtropical conditions.
Try: Green Harvest, Eden Seeds
Spring Onion (Straight Leaf)
Harvest young as green onions. Fast (8-10 weeks). Year-round in SEQ.
Try: Yates, Mr Fothergill's, Bunnings
Position and Soil
Give Onion full sun (at least 6 hours a day). It does best in free-draining soil with a pH around 6 to 7. Dig through plenty of compost before planting, and mulch to hold moisture and keep weeds down. It can be container-grown in 30cm+, though it is happier in the ground.
Sowing and Spacing
Sow seed about 1.5 cm deep. Thin or space plants to about 10 cm apart. Seedlings usually appear in around 12 days, fastest when the soil is between 10 and 25 degrees.
Long haul, plant once, wait six months. Day-length sensitive; pick short-day varieties for SEQ.
Care
Water consistently, roughly 3 L per plant every 3 days in warm weather, less in cool or wet spells. Feed every few weeks through the growing season with a balanced organic fertiliser, and keep mulch topped up.
Pests and Diseases
Keep an eye out for Thrips. The main diseases to watch are Downy mildew, White rot and Onion smut. Good spacing, watering at the base rather than over the leaves, and crop rotation prevent most problems. See our Pest and Disease Guide to identify and fix any issue.
Harvesting and Storage
Onion is typically ready to harvest in about 6 months. Dry, cool, dark place, up to 3 months. Do not refrigerate until cut.
In the Kitchen
In the kitchen, onion is good caramelised slowly as a base, pickled raw for burgers and tacos, added raw to salads and salsas and roasted whole as a side dish. Nutritionally: contains quercetin, a powerful antioxidant and supports heart and immune health.
Companion Planting
Onion grows well alongside Carrot, Beetroot, Lettuce, Silverbeet and Chamomile. Keep it away from Beans and Peas. Our Companion Planting Guide has the full pairings.
Track Your Onion Growing
Add onion to your garden in the Planting Season app and get reminders for planting, care and harvest, tuned to your region.
Open the App →Frequently Asked Questions
When should I plant Onion in Australia?
Onion is a cool-season crop. In subtropical regions like South-East Queensland it is sown in March, April, May and June. Timing changes with your climate, so use the calendar above for your region.
How long does Onion take to grow?
Onion is generally ready to harvest in about 6 months.
How much sun does Onion need?
Give it full sun (at least 6 hours a day) for the healthiest growth and best harvest.
See also: Onion in the Plant Library
