Onion, Allium cepa, is a wonderful culinary and medicinal vegetable which has been cultivated for thousands of years.


Alliaceae (formerly Liliaceae)


Common onion, bulb onion




Onions are native to the Asian steppes and are cultivated throughout the world.


Hardiness: USDA zones 3 to 9
Height: 30 cm (1 foot)
Width: 15 cm (6 inches)
Flowers: Small, green-white clustered in globes
Leaves: Thin and narrow, straight and pointed, green
Blooms: Summer months


Propagation: seeds or sets
Germination: 15-20 days at 8-20 degrees Celsius
Spacing: 5 cm (2 inches) between the seeds or 10 cm (4 inches) between the sets, and 30 cm between the rows.
Soil: Rich and well-drained. Freshly manured ground can lead to rotting.
pH: 4.5 to 8.5
Exposure: Full sun
Pests and diseases: Onion thrips, armyworms, cutworms, white rot, Fusarium wilt, iris yellow spot virus, pink root, downy mildew, purple blotch, damping-off, Stemphylium blight, basal rot/bottom rot, onion smut, black mold, seven curl disease, neck rot, sour skin, bulb cancer/skin blotch, bacterial brown rot, onion yellow dwarf virus, root-knot nematode, onion maggot
Garden Design: Like garlic, onions look good in clusters in the herb garden, around roses, and under fruit trees.
Companion planting: Onions are great companions to dill, cucumbers, garlic, marjoram, carrots, roses, lettuce, tomatoes, fruit trees. However, they hinder the development of beans, peas and cabbage. Avoid planting onions next to leeks as both plants attract the same kind of pests.


Onions can be harvested from July to September when the leaves turn yellow and start to topple over.


Brush the earth off the bulb and let it dry them for two to three weeks laid out in the sun or in a well-ventilated indoor area if the weather is wet . Washing the bulbs promotes rot.


Sulfur rich volatile oils, vitamins c and B, potassium, peptides, flavonoids, diphenylamine


Anti-inflammatory, antibiotic, antiviral, antispasmodic, diuretic, digestive, vulnerary, cicatrizant


Hot, dry


Pungent, spicy


When uncut: weakly aromatic. When cut: characteristically alliaceous.


Onion is an inexpensive medicinal and culinary plant used to prevent asthma attacks and colds, sooth coughs and keep the blood vessels young.

The sulfur compounds, mostly allicin, present in onions are responsible for the strong, characteristic smell and for the medicinal value of onions. The antibiotic and antiviral properties of allicin coupled with the high vitamin C content of onions, make this popular culinary herb a great preventive medicine for colds and flu. It soothes inflammation of the upper respiratory tract, relieves coughs, and eases asthma attacks.

Onions are also good for preventing blood vessel changes due to aging such as arteriosclerosis, especially when combined with garlic.

Like garlic and many culinary herbs, onions regulate the secretion of digestive juices which stimulates the appetite and improves digestion. Onions are also diuretic.

When used externally, onions promote the healing of wounds (vulnerary) and the destruction of parasites. It can soothe insect bites. However, an onion applied to the skin can also cause skin irritation and hives (urticaria).

Used internally for:

  • Colds and flu
  • Asthma attacks
  • Coughs
  • Sore throat
  • Arteriosclerosis (thickening, hardening and loss of elasticity of the walls of arteries)
  • Destroying microbes, worms and maggots
  • Stimulating the immune system
  • Improving intestinal flora

Topic application for:

  • Wounds
  • Inflammation of the middle ear (otitis media)
  • Insect bites

Recommended daily dosage: 50 g (per German Commission E)
Expelled juice: 1 tablespoon 3 times per day

  • Juice
  • Powder

Onions are a very versatile kitchen ingredient and can be baked, boiled, braised, grilled, fried, roasted, sautéed, or eaten raw in salads. They can be used to season many warm dishes as well as served on their own such as French onion soup and onion rings.


None known


People who are allergic or sensitive to onions should, obviously, not consume any onions.


Bühring, U. 2014. Alles über Heilpflanzen. 4th ed. Stuttgart: Haug.
Weinrich, C. 2015. Mischkultur im Hobbygarten. 4th ed. Sttuttgart: Ulmer

Learn how to grow a gorgeous medicinal and culinary garden with Giovanna Becker

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