The Ingredient Library
Onion Seed
Allium cepa
Onion seed oil is cold-pressed from the small black seeds of Allium cepa, the common onion, which only sets seed when the plant is kept growing into a second season to flower.
Get to know onion seed oil
- Source
- Seed
- Origin
- Grown worldwide
- Extraction
- Cold-pressed
- Texture
- Light to medium
What it is
Onion Seed is a botanical carrier oil used in hair and skin care.
Why it belongs in your routine
Seed oil pressed from the small black seeds of the common onion plant.
How to use
Warm a few drops between your palms and smooth over hair or skin. Patch test before use.
Where does onion seed oil come from?
Onion seed oil comes from Allium cepa, the bulb onion, a biennial plant usually grown as an annual crop for its bulb. Its hollow blue-green leaves rise from a swollen bulb of layered, fleshy scales. To produce seed, growers leave the plant in the ground or replant the bulbs so they flower in their second season. Each tall stalk carries a round head of small white flowers that ripens into capsules of hard, angular black seeds.
The seeds hold roughly 11 to 17 percent oil. Cold-pressed onion seed oil has a mild onion scent. Linoleic acid is its main fatty acid, followed by oleic and palmitic acids. It is used on its own as a scalp and hair oil, and in hair oils and balms where a light to medium feel is wanted.
Sourcing & extraction
How onion seed oil is sourced and extracted
Why it is rare
Most onions are pulled as bulbs in their first year and never flower. A seed crop needs a second season, and the seed heads ripen unevenly, so they are often cut by hand in several passes. The seeds also hold only a modest share of oil.
How it is gathered
Onion seed is grown as a specialist crop, usually in warm, dry areas where the seed heads can ripen without rain. Bulbs from the first season are replanted, or plants are left in the field, and the flower stalks grow through spring. When the first capsules turn papery and split to show black seed, the heads are typically cut, dried on sheets or racks, and threshed. The cleaned seed is then sold for sowing or sent to presses for oil.
How it is made
Cold-pressed from the seed
- Ripe onion seed heads are cut when the first capsules split, then dried on sheets or racks.
- The dried heads are threshed and the black seed is cleaned of chaff and broken stalk.
- The clean seed is fed through a screw press without added heat, which squeezes out the oil.
- The oil is left to settle, then filtered to remove fine seed particles before bottling.
How to use onion seed oil
- Start with a few drops and warm them between your palms.
- Massage into clean skin, or work through the lengths of damp or dry hair.
- Use on its own, or add a few drops to your moisturizer or conditioner.
For external use only. Patch test on a small area before first use and stop if irritation occurs. If you are pregnant, nursing or have a medical condition, ask a healthcare professional before use.
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Questions about Onion Seed
Where does Onion Seed come from?
Onion seed is grown as a specialist crop, usually in warm, dry areas where the seed heads can ripen without rain. Bulbs from the first season are replanted, or plants are left in the field, and the flower stalks grow through spring. When the first capsules turn papery and split to show black seed, the heads are typically cut, dried on sheets or racks, and threshed. The cleaned seed is then sold for sowing or sent to presses for oil.
How is Onion Seed extracted?
Cold-pressed from the seed. Ripe onion seed heads are cut when the first capsules split, then dried on sheets or racks. The dried heads are threshed and the black seed is cleaned of chaff and broken stalk. The clean seed is fed through a screw press without added heat, which squeezes out the oil. The oil is left to settle, then filtered to remove fine seed particles before bottling.
Why is Onion Seed considered rare?
Most onions are pulled as bulbs in their first year and never flower. A seed crop needs a second season, and the seed heads ripen unevenly, so they are often cut by hand in several passes. The seeds also hold only a modest share of oil.
