Plant field guide
Onion
Essential kitchen garden crop available as bulbing, bunching, and pearl types. Choose long-day or short-day varieties based on your latitude.
Growing requirements
- Scientific name
- Allium cepa
- Sun
- full sun
- Water
- moderate
- Height
- 12 in (30 cm) – 18 in (46 cm)
- Spread
- 4 in (10 cm) – 6 in (15 cm)
- Spacing
- 4 in (10 cm)
- Hardiness zones & minimum temperature
- USDA 3–9; average annual extreme minimum from -40°F (-40.0°C). Hardiness does not predict local frost dates.
- Difficulty
- moderate
Planting & seasonal timing
Northern Hemisphere planting months: not yet verified in our database.
Northern Hemisphere pruning months: no calendar months recorded.
For the Southern Hemisphere, these seasonal windows shift approximately six months. Check your local frost forecast, soil temperature, and species requirements; calendar months are not a guarantee of planting safety.
Choose correct day-length variety for your region. Stop watering when tops begin to fall over. Cure in dry location for storage.
Pruning
No pruning needed. Allow tops to fall naturally to signal harvest readiness.
Fertilizer
Balanced fertilizer with nitrogen
Every 2-3 weeks during active growth, stop when bulbing begins
Mulch
Light straw mulch between plants.