Permapotes
Onions

Red onion

Red onion: Sowing, planting and harvest calendar

Red onion is a form of Allium cepa, in the Amaryllidaceae family. It is recognisable by red to purple outer skins and fleshy layers that are often white with reddish purple edges or tints. This colour distinguishes it visually from yellow and white onions without making it a separate species. The name encompasses several cultivars, whose shape, size and culinary qualities can differ.

The bulb consists of thickened leaf bases arranged in layers around a centre. Dry outer coverings protect the fleshy inner parts. The contrast between those layers explains the coloured rings visible in a cut section. Depending on the cultivar, the bulb may be round, flattened or more elongated. ‘Red Baron’ is one example with dark red skin and white flesh edged in red. It illustrates a particular cultivar rather than every red onion.

Above the bulb, the plant carries elongated, hollow green leaves. This upright outline contrasts with the rounded mass of the storage organ below. The onion generally has a biennial life cycle, even though it is commonly grown for its bulb within one cropping season. When the plant enters its reproductive phase, a flower stalk carries a cluster of many small flowers. Bulb, leaves and flowers therefore represent different aspects and stages of the plant’s development.

Its flavour combines sweetness and pungency in varying proportions. A red onion is not necessarily milder than a yellow onion: the cultivar and the qualities of the individual bulb matter as well as colour. Raw onion brings crunch and an aromatic note to salads, garnishes and cold dishes. Cooked, you can find it in soups, savoury tarts, sautéed dishes, sauces and vegetable accompaniments. Its use is not limited to a single style of cooking.

Reddish purple rings add visual interest to preparations in which the bulb remains recognisable. Colour can change during cooking, so the final appearance is not always identical to that of the raw onion. In the vegetable garden, red onions add another palette to bulb onions, with restrained foliage and varied bulb outlines. Earliness and storage qualities remain cultivar characteristics, without a universal storage period implied by the name red onion alone.

Red onion
Red onion
Characteristics
  • Lifecycle : Annual
  • Exposure : Full Sun
  • Frost Hardiness : Frost Resistant
  • Cultivation Difficulty : Easy
  • Mature height : 30 cm
Sowing & Planting
  • Greenhouse Growing : Not Required
  • Sowing Depth : 2 cm
  • Plant Spacing : 10 cm
  • Row Spacing : 20 cm
Maintenance
  • Maintenance : Low
  • Water Requirements : Moderate
Other characteristics
  • Soil Type : Humus-rich
  • Soil pH Preference : Neutral
  • Pest Sensitivity : Moderate
  • Disease Sensitivity : Moderate
  • Weed Sensitivity : Moderate
  • Pollination : Insect-pollinated
  • Propagation : Sowing