The Allium genus comprises many species. Some, such as onions, have edible leaves and bulbs and are considered to be vegetables, whilst others, such as garlic and chives, are thought of as herbs.

Onions have been cultivated since the time of ancient Egyptians and are a good winter crop for the home gardener. Whether they are called onion, spring onion, scallion or shallot (pictured below left) tends to vary in different parts of Australia.


There are many onion varieties and for best results the appropriate one needs to be chosen for different climatic zones (check the back of the seed packet). Early onions may be sown from February to May in warm northern areas of Australia.

In Sydney onions may be sown from March to May or for mid-season varieties, sow in June or July. In the cold southern areas, onions can be sown progressively from April to September.

Onions may bolt (go to seed) if they are not planted at the appropriate time of the season. They prefer to grow in a sunny, open position with well drained soil.

Onion seed can be sown in beds or punnets and transplanted when the seedlings are 10cm or so high. They should be planted 10-15cm apart in rows 20 to 30cm apart. They are laid on the ground and the roots are just covered with soil. They will right themselves in a few days.

Alternatively seeds may be sprinkled thinly into a narrow furrow, covered lightly and watered gently. They will emerge in around 2 weeks and should be thinned. A bed that was well prepared with organic matter and manure will not require further fertilising.


The onions will be ready to harvest in six to eight months. They are ready when the leaves dry and fall over. After they are pulled out they should be left in the sun for a few days. When the skin is quite dry the top is screwed off and the roots rubbed off. They are then stored in wire baskets or mesh bags in a cool dry place.

The early varieties such as ‘Early Barletta’ and ‘Hunter River White’ do not store as well as later varieties. Barletta may be lifted at 70 days for pickling or left to mature as a salad onion (pictured here).

‘Sweet Red’ is a mid season variety which stores reasonably. ‘Brown Spanish’ (pictured at top) keeps very well and may be planted late. ‘Borettana Yellow’ is a late variety which may be pickled or used as a salad onion.

Other salad onions are ‘Spring Onion’ or ‘Shallot Bunching Onion’ which can be sown directly from spring through to autumn. It is not usual to thin them as they may be harvested from eight to twelve weeks. For repeat harvesting sow more every four weeks. They may be grown in containers.

The tree onion and potato onion are grown from small sets of bulblets planted in autumn. Both form bulbs below ground, and the tree onion also forms bulbs at the top of the stem.

Pest and disease problems

Onion failure may be caused by growing a variety not suited to the climate (check the packet). Downy mildew occurs in damp conditions. It is difficult to control but a copper based spray may help.

White rot (Sclerotium cepivorum) may be a problem controlled by using fungicides at sowing time but it is almost impossible to eliminate. Crop rotation will help but, if the problem is identified, don’t grow any alliums in that soil again for at least ten years. It is a major disease in south Queensland.

Onion thrip (Thrips tabaci) is a pest which also is very difficult to control if present. See our information sheet on Thrip.

Other uses

Onions are a good companion plant. Grown around the garden they repel pests. They contain sulphur which is a strong disinfectant. In the past it was used to heal gun shot wounds and during World War 1, sphagnum moss was soaked in garlic juice as a wound dressing. Garlic may prevent Peach Leaf Curl and Black Spot of Rose. It is said they should not be planted near corn or beans.

Information sources:
Yates Garden Guide, 42nd Edition, 2006, published by Harper Collins Publishers
Blazey, C., The Australian Fruit and Vegetable Garden, 2006, published by The Diggers Club.
Department of Primary Industries Queensland, 1994, Disease of Vegetable Crops.
Kirton, M., 2003, Dig – Modern Australian Gardening, published by Murdoch Books.