Allium cepa

Allium cepa

onion

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Taxonomy

Common Names

onionbulb onioncommon onion

Context

nativeRegion

Central Asia (likely Iran and Afghanistan).

usdaZones

5–10

companionPlants

Carrots, Lettuce, Beets, Strawberries

culturalUses

Widely cultivated for culinary use worldwide; fundamental in many cuisines.

Care

LightFull sun; requires at least 6 hours of direct sunlight per day.

WateringModerate; keep soil consistently moist but not soggy. Avoid overwatering.

SoilWell-draining, fertile soil with a neutral to slightly acidic pH (6.0–7.0).

FertilizerApply balanced fertilizer at planting and during bulbing stage.

HumidityTolerates a wide range of humidity; prefers moderate humidity levels.

TemperatureGrows best in cool to moderate climates, optimal range is 13–25°C (55–77°F).

HabitHerbaceous biennial (commonly grown as annual for bulbs).

Mature SizeBulbs reach 5–10 cm (2–4 in), leaves up to 45 cm (18 in) tall.

Growth RateModerate; bulb maturity in 80–150 days from sowing.

BloomingProduces umbel inflorescence in second year with small, star-like flowers.

DormancyBulbs enter dormancy after foliage dies back post-harvest.

MethodsSeed, Bulblets (sets), Division

DifficultyEasy

Best SeasonStart seeds indoors in late winter; transplant or direct sow in early spring.

PruningRemove flower stalks to enhance bulb size; cut yellowing leaves at season end.

RepottingNot typically needed; grown as field or garden crop.

Pests & DiseasesSusceptible to onion maggots, thrips, downy mildew, and rot.

ToxicityToxic to cats, dogs, and some livestock if ingested.

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