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Save your seeds: Onion

Photo by Graham Corney
Photo by Hanif66

Clockwise from above: Onion seeds and seed head; Onion Seed; Onion seed heads and dried onions.

Photo by Dalaifood

BOTANICAL NAME: Allium cepa. In Latin, allium means garlic and cepa means onion.


Onion is a hardy biennial from the southern parts of Russia and Iran. It was disseminated by the Indo-European hordes in their numerous migrations.

Very ancient forms of onions are still for sale in Middle Eastern markets. Onions were considered sacred and were eaten in copious quantities by the Egyptians who honoured them in some of their monuments.

In recent times, UN officials have found old varieties in Iran that show resistance to thrips and this has greatly benefited the industry. Thrips are slender insects with stout, coneshaped mouth parts with which they scrape the onion stems and suck out the sap, causing yellowing of the leaves.


Onions have many close relatives, such as A. cepa var. aggregatum (French shallot, potato onion and multiplier onion), A. cepa var. proliferum (tree onion) and A. fistulosum (spring onion).


Bending the leaves late in the season will stop premature bolting and encourage development of the bulb. Onions may not form bulbs or seed at all if moved to a different latitude. A Tasmanian onion, for example, is unlikely to produce seeds in North Queensland, even if grown on the cool Atherton Tableland.


Several varieties can be grown in the same garden in the first year of their growth. To ensure purity, only one sort should be allowed to flower in the second spring within a 400 metre radius.

At least twenty plants of a variety must be saved in order to maintain diversity for the long term, but the optimum number should not deter you from saving onion seeds if you have grown only a small number of plants.

Onions are pollinated by insects. Some collectors or curators of onions actually bag their onion flower heads. This involves the hand-pollination of at least twenty individual heads of each variety, moving pollen with a camel brush from head to head each morning for a month. More simply, onion seed breeders introduce pollinating insects into the cages in which onions are isolated.

Choose well-formed and firm onions for seed purposes. Large onions produce more seed than small ones, but it is worthwhile looking at the whole plant when it is growing and tagging it, rather than just choosing the largest at harvest. The flowering stalk which develops in the second season is leafless, hard and hollow and can grow up to two metres tall. As onions go to seed very rapidly, a stake may be needed at this time.

Seeds are ripe when the stalk changes colour to brownish. The seeds become black and the capsules begin to open and drop seeds if shaken. All the plants’ heads do not come to seed at the same time, so they may have to be harvested at random. Put the heads in a paper or cloth bag and hang in a dry shady place. When dry, shake and rub the bunch. A mixture of seed, capsule and stems will result.

Little white dried calyces will be among the seeds. The mix can be sieved and winnowed or simply blown upon gently until only black seeds are left.


The seeds will last only one to two years. They are best kept in cold and dry storage after complete drying. Onion seeds lose vitality very quickly in warm and humid climates. There are 250 seeds to the gram.


Onions are much sweeter when grown in warm climates.

Because onions in general respond to day length for forming bulbs, local varieties are best. Ask market gardeners for their advice on which to grow.

Onion is believed to be unsuitable for people who are prone to skin disorders or who are of a nervous disposition. Onion is reputed to loosen phlegm, drain mucus from the nose and have antiseptic properties. Onion is also helpful for lowering blood pressure and blood sugar. Try rubbing raw onions on cracked feet for quick relief.

Foodwise, onions are versatile inclusions to many dishes. Add them to soups, curries, jam, pasta, pizza, burgers, salads, tarts and even bread.

Adapted from The Seed Savers’ Handbook by Jude and Michel Fanton (Seed Savers’ Network 1993)


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