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Vegetable
Onion
Allium cepa
A staple crop sown in autumn and winter in Adelaide and harvested in late spring and summer. Choosing the right type matters: onions bulb according to day length, so use short- or intermediate-day varieties suited to southern Australia. Keep beds weed-free, as onions hate competition.
- SunFull sun
- Spacing10 cm apart
- First pick21–29 weeks
- FrostFrost hardy
- HeatCopes with some heat
- Sow depth6 mm
When to plant where you live
Checking your area…
Add onion to my gardenTake care with pets and children
Pets: Seriously toxic. Children: Not known to be toxic. Parts: all. Toxic to dogs and cats.
Varieties (4)
- CreamgoldAustralian long-keeping brown onion; sow in winter
- Early BarlettaSmall white pickling or salad onion; quick and easy
- Gladalan BrownIntermediate-day brown onion bred for southern Australia; good keeper
- Red Burgundy (Red Odourless)Mild sweet red onion for salads; shorter storage
Neighbours
Grows well with
Keep away from
From seed to plate
Plant
10 cm apart, seed 6 mm deep. Full sun.
Water
Regular until bulbing, then ease off.
Feed
Compost; avoid excess nitrogen.
Pick, from about 21 weeks
Harvest when tops fall over.
Good to know
- Plant seedlings shallowly with the bulb base just covered
- Stop watering when the tops start to fall over
- Weed by hand often; onions have few leaves to shade weeds out
Common problems
- Bolting (flower stalks)don't sow too early; use varieties suited to your season
- Onion thrips (silvery streaks) in dry spring weatherhose foliage, keep watered
- Downy mildew in damp weatherspace for airflow, water the soil not leaves
- Bulbs rot in storagecure in a dry airy place until necks are fully dry
If you use a garden chemical, follow the label exactly. Try organic options first, and ask the community or Plant Doctor if you're unsure.
Where this information comes from
- Australian seed company regional sowing charts (temperate zone) (germination, low confidence)
- UC Master Gardener Program (UC ANR): soil temperature conditions for vegetable seed germination (germination, medium confidence, checked 27 Oct 2026)
- Pip Magazine: How to start growing onions (growing, medium confidence, checked 27 Oct 2026)
- ABC Gardening Australia fact sheets (growing, low confidence)
- Sustainable Gardening Australia: planting guides (sowing window, low confidence)
- Poisons information centre plant guidance (Australia) (toxicity, low confidence)
- ASPCA Animal Poison Control: Onion (toxicity, high confidence, checked 27 Oct 2026)
- PDSA Pet Health Hub: onion and garlic poisoning in dogs (toxicity, high confidence, checked 27 Oct 2026)
Reviewed by AI cross-check (Claude), not a horticulturist on 27 Oct 2026. Version 2.