What are the optimal conditions for curing onions?
Written by
Benjamin Miller
Reviewed by
Prof. Charles Hartman, Ph.D.Proper curing conditions Good curing is crucial for long-term storage of onions. Maintain a temperature of 70 to 90°F throughout. Humidity levels should be maintained between 50% and 70% for optimal results; otherwise, bulbs may mold or become too dry. Turn air currents around every bulb; tough skins and sealed necks.
Temperature Control
- 70-90°F (21-32°C) range ideal for enzyme activity
- Below 60°F slows drying causing internal mold
- Above 95°F cooks bulbs destroying flavor
Humidity Management
- 50-70% prevents skin cracking or moisture retention
- Below 40% causes outer layer desiccation
- Above 75% encourages fungal growth
Airflow Requirements
- Oscillating fans 6 feet away provide even circulation
- Stack bulbs in single layer on mesh racks
- Rotate positions every 3 days for uniform drying
Light, or lack of it, affects the result of curing - so expose to the sun for the first two days to kill the surface germs and then remove to total darkness. Light produces sprouting during the curing period, and in my curing shed, I use double curtains so that even the slightest light cannot penetrate. My results are perfect every time.
Test for completion with the neck snap method. Bend the stems; they should break cleanly, not flex or bend. Squeeze the bulbs; they should feel rock hard. Shake them, listen for the papery rustling sound. This well-cured onion should keep for 6-12 months, depending on the variety.
Read the full article: When to Harvest Onions: Ultimate Guide
