The onion (Allium cepa L., from Latin cepa “onion”), the most widely cultivated vegetable of the genus Allium. Its close relatives include the garlic, shallot, leek, chive and Chinese onion. The word onion comes from the Latin word ‘unio’ meaning unity, because it grows as a single bulb.
The onion is most frequently a biennial or a perennial plant but is usually treated as an annual and harvested in its first growing season. Onions are cultivated and used around the world. As a food item, they are usually served cooked, as a vegetable or part of a prepared savoury dish, but can also be eaten raw or used to make pickles or chutneys.
The onion plant has a fan of hollow green leaves and its bulb at the base of the plant begins to swell when a certain day-length is reached. The bulbs are composed of shortened, compressed, underground stems surrounded by fleshy modified scale (leaves) that envelop a central bud at the tip of the stem. In the autumn (or in spring, in the case of overwintering onions), the foliage dies down and the outer layers of the bulb become dry and brittle. The crop is harvested and dried and the onions are ready for use or storage.
The geographic origin of the onion is uncertain because the wild onion is extinct and ancient records of using onions span all over Asia. The first cultivated onions are the subject of much debate, but the two regions that many archaeologists, botanists, and food historians point to are central Asia or Persia. They were probably almost simultaneously domesticated by peoples all over the globe, as there are species of the onion found the world over. Food uses of onions date back thousands of years in China, Egypt and Persia. Traces of onions recovered from Bronze Age settlements in China suggest onions were used as far back as 5000 BC, not only for their flavour, but the bulb’s durability in storage and transport. Ancient Egyptians revered the onion bulb, viewing its spherical shape and concentric rings as symbols of eternal life. Onions were used in Egyptian burials, as evidenced by onion traces found in the eye sockets of Ramessess IV. The fourth book of the Hebrew Bible composed around the 5th century BC mentions onions when recounting scarce foodstuffs available: 11:5 — We remember the fish which we used to eat free in Egypt, the cucumbers, the melons, the leeks, the onions, and the garlic. In the 6th century BCE, the Charake Samhita, one of the primary works in the Ayurvedic tradition, documents the onion’s use as a medicinal plant, a ‘diuretic, good for digestion, the heart, the eyes, and the joints’. Pliny the Elder wrote about the use of onions and cabbage in Pompeii. He documented Roman beliefs about the onion’s ability to improve ocular ailments, aid in sleep, and heal everything from oral sores and toothaches to dog bites, lumbago and dysentery. Archaeologists unearthing Pompeii long after its 79 CE volcanic burial have found gardens resembling those in Pliny’s detailed narratives where the onions would have been grown. Onions were taken to North America by the first European settlers only to discover the plant readily available, and in wide use in Native American cooking. According to diaries kept by certain of the first English colonists, the bulb onion was one of the first crops planted by the Pilgrims.
Shallots are a type of onion, but was formerly classified as a separate species, A. ascalonicum. Like garlic, shallots are formed in clusters of offsets with a head composed of multiple cloves. The skin colour of shallots can vary from golden brown to gray to rose red, and their off-white flesh is usually tinged with green or magenta. You can use shallots in the place of onions when cooking, but they do make smaller harvests.
In the gardening world, we are used to three different colours of onions. We grow the brown/yellow/golden, the red/purple and then the white, which I must admit, I have never tried. Across the world the brown is often used in everyday cooking, the red is often served raw as it is sweeter, and the white are often used in Mexican styled cuisine as they are very sweet once sautéed.
Here are some varieties to try:
Brown: Radar (one of my favourites), Alisa Craig, Stuttgarter, Centurion, Hercules, Sturon, Hytech
Red: Red Baron, Electric (another favourite)
Shallot: Griselle (good), Jermor, Bistro, Golden Gourmet, Picasso, Mikor, Yellow Moon, Vigarmor
Onions are best cultivated in fertile soils that are well-drained. Sandy loams are good as they are low in sulphur, while clayey soils usually have a high sulphur content and produce pungent bulbs. Onions require a high level of nutrients in the soil. Phosphorous is often present in sufficient quantities, but may be applied before planting because of its low level of availability in cold soils. Nitrogen and potash can be applied at regular intervals during the growing season, the last application of nitrogen being at least four weeks before harvesting. Or try planting them in your crop rotation after the runner beans. Bulbing onions are day-length sensitive; their bulbs begin growing only after the number of daylight hours has surpassed some minimal quantity. Most traditional European onions produce bulbs only after 14 hours or more of daylight. Southern European and North African varieties are often known as “intermediate-day” types, requiring only 12–13 hours of daylight to stimulate bulb formation. “Short-day” onions, which have been developed in more recent times, are planted in mild-winter areas in the autumn and form bulbs in the early spring, and require only 11–12 hours of daylight to stimulate bulb formation. Onions are a cool-weather crop. Hot temperatures or other stressful conditions cause them to bolt, meaning that a flower stem begins to grow.
Onions may be grown from seeds or from sets. We often use sets (I’ve tried shallot seeds and grown a total of two miniature shallots that were the size of my pinkie’s fingernail…) Onion seeds are short-lived and fresh seeds germinate better. The seeds are sown thinly in shallow drills, thinning the plants in stages. In suitable climates, certain cultivars can be sown in late summer and autumn to overwinter in the ground and produce early crops the following year. Onion sets are produced by sowing seed thickly in early summer in poor soil and the small bulbs produced are harvested in the autumn. These bulbs are planted the following spring and grow into mature bulbs later in the year. Certain cultivars are used for this purpose and these may not have such good storage characteristics as those grown directly from seed.
If growing from seed, sow 1cm (½in) deep in rows 20cm (8in) apart from late February through to early April. Thin by removing weaker seedlings, first to 5cm (2in) apart and then later to 10cm (4in) apart. Plant spring sets March – April and harvest August – September. Plant winter sets in September and harvest May – June. Plant onion sets 10cm (4in) apart in rows 30cm (12in) apart. Gently push the sets into soft, well-worked soil so that the tip is just showing, and firm the soil around them.
Routine care during the growing season involves keeping the rows free of competing weeds, especially when the plants are young. The plants are shallow-rooted and do not need a great deal of water when established. Bulbing usually takes place after 12 to 18 weeks. The bulbs can be gathered when needed to eat fresh, but if they will be kept in storage, they should be harvested after the leaves have died back naturally. In dry weather, they can be left on the surface of the soil for a few days to dry out properly, then they can be placed in nets, roped into strings, or laid in layers in shallow boxes. They should be stored in a well-ventilated, cool place such as a shed.
Freshly cut onions often cause a stinging sensation in the eyes of people nearby, and often uncontrollable tears. This is caused by the release of a volatile gas, syn-propanethial-S-oxide, which stimulates nerves in the eye creating a stinging sensation. This gas is produced by a chain of reactions which serve as a defence mechanism. Chopping an onion causes damage to cells which releases enzymes called alliinases, generating sulfenic acids. Lacrimal glands produce tears to dilute and flush out the irritant.
Onions are rich in carbohydrates, sugar, soluble and insoluble fiber, sodium. They are a very good source of vitamin C and so good for building your immunity. They are also a good source of enzyme-activating manganese and molybdenum as well as heart-healthy vitamin B6, fiber, folate, and potassium. Onions are surprisingly high in flavenoids, one of the top ten vegetables with Quercetin content. If you want to retain the flavonoid, peel off only the outer dry skin as the outer layers are more concentrated with flavenoids. Onions have been found to have anti-inflammatory properties and help in problems like rheumatoid arthritis or allergic airway inflammation. Studies show that onions help balance blood sugar levels. Onions also have anti bacterial properties. There are many stories and folklore. It is supposed to have saved families from plague and other infections. The anti bacterial effects of the onions act against the streptococcus mutants that cause various dental cavities and gum diseases. Studies suggest that the consumption of onions enhances the anti clotting capacity of blood. Onions have been known to increase bone density, reducing the risk of fractures. The sulphur content in onions is excellent for the connective tissues as well.
Natural treatments that use onion:
-Onions are also used in the treatment of piles or haemorrhoids. The juice of 30g of onion mixed with water and sugar is administered to the patient twice a day.
-In alopecia (hair loss), a topical application of onion juice has been said to initiate the re-growth of hair.
–Cough, cold and asthma is often treated with a serving of onions, as it is known to decrease bronchial spasms. Onion juice mixed with honey helps cure bronchitis and influenza.
-Onions are also known to stimulate the growth of good bacteria while suppressing the growth of harmful bacteria in the colon, reducing the risk of colon cancer.
-The juice of Tulsi leaves (holy basil) with equal quantities of lemon juice and onion extract applied on the skin takes care of many skin diseases.
-A slice of cut onion rubbed over acne is supposed to clear up the skin quickly by taking off the bacterial infections.
-Naturopaths recommend eating onion and jaggery to increase body weight.
-Eating one raw onion a day reduces cholesterol in the blood.
-A remedy for warts is the application of the juice of one finely chopped onion sprinkled with salt and left for a few hours. This needs to be repeated 3 to 4 times a day until the wart dries up.
-The cure for cholera in Indian households is one onion pounded with 7 black peppers. It lessens vomiting and diarrhoea immediately. A little sugar could be added to the mixture to increase its effectiveness.
-A tea made of onions boiled in water, cooled, strained, and given to patients suffering from urinary infections gives immediate relief.
-Slice an onion and rub it over the sting of a bee, wasp or a mosquito to ease the discomfort.
-In the treatment for chicken pox, Indian women would serve the afflicted person a bowl of curd rice with chopped onions.
Onions can be added to anything. They are the base of all sauces, add flavour to a salad when served raw, and are just fundamental in the kitchen for pizza toppings, curries, stir fries, pies…
Here are some wonderful recipes using onions:
Pasta salad with fried onions and tomatoes : Autumn planting … and a recipe!
Recipe: Baked Potatoes and Kidney Beans
Aubergine (Eggplant) Curry
And lots more – just type onion into the search bar on the home page.