Onion
Allium cepa · Amaryllidaceae
📷 Mehdi · CC BY-SA 3.0
⚠️ Bulbes et feuilles peuvent endommager les globules rouges des chiens et surtout des chats ; le risque dépend de la quantité ingérée, crue ou cuite.
The gardener's calendar
Ideal time to plant onion: set it out when the soil is neither frozen nor waterlogged, and water generously as it establishes.
ID card
- Family
- Amaryllidaceae
- Type
- Bulb
- Adult height
- Up to 100 cm (flower stem)
- Foliage
- Deciduous, herbaceous
- Flowering
- June to July
- Exposure
- Full sun
- Water requirement
- Moderate
- Hardiness
- Very hardy, down to -15 °C
✓ Taxonomy verifiedSource: AI estimate · hardiness: reliability high.
Expert tips
The key tip
Sow very early in February-March for well-formed bulbs by summer: water regularly until June, then reduce watering to dry them out before harvest.
The common mistake
Harvesting too early before foliage completely dries out: onions only keep for a few weeks if picked green.
The pro's trick
Lightly trim the foliage 2 weeks before planned harvest to improve air circulation and speed up bulb drying.
Care
Exposure
The onion requires at least 6 hours of direct sunlight daily for good bulb development. Plant it in full sun, on a well-exposed plot. Optimal exposure ensures better accumulation of reserves and more pronounced flavor.
Watering
Water regularly in spring and early summer, keeping the soil moist but not saturated. As the bulb forms and leaves yellow (late June-July), gradually reduce watering. Stop watering 2 to 3 weeks before harvest to encourage maturation and drying.
Soil
The onion prefers well-drained soil, slightly acidic to neutral, rich in organic matter but without excess nitrogen. Loosen the soil deeply before planting. Avoid compacted or waterlogged soil, which would promote bulb rot.
Fertilizer
Apply balanced fertilizer at the start of growth or incorporate well-decomposed compost when preparing the soil. Excess nitrogen promotes leaf growth at the expense of the bulb. Moderate application is generally sufficient for a good harvest.
Monitoring and harvest
No pruning is needed during cultivation. Harvest when leaves naturally flatten and yellow (July-August). Gently lift the bulbs and let them dry for a week in the sun before storing them in a dry, cool place.
Diseases and pests
Watch for onion flies and thrips, particularly in summer. White or gray rot can occur in overly moist soil. Ensure good drainage and avoid excess moisture. Remove affected plants to limit spread.
Did you know?
The onion has been cultivated for over 5,000 years in ancient Egypt, where it was revered as a symbol of eternity because of its concentric layers. The Egyptians placed it in the tombs of pharaohs and used it as a religious offering. Today, it is one of the most widely cultivated vegetable plants globally, essential to the cooking of hundreds of cultures.
Where to buy it
Plant the bulbs in autumn for spring flowering. Pick a plant with healthy foliage and roots that are not exposed. Best time: from September to November.
Add this plant to my garden →Plants from the same family
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- Belladonna lilyAmaryllis belladonna
- Allium senescensAllium senescens
Tips generated and checked by Viridia — adapt them to your local climate.