China cold storage solution provider
Onions are one of the world’s most traded vegetables—but without proper storage, they sprout, rot, or lose weight within weeks. At ambient temperatures, post-harvest losses can reach 25–40% during hot seasons.
But with the right cold room, you can:
✔️ Store onions for 2 -3months
✔️ Suppress sprouting and decay
✔️ Sell during off-season peaks at 2–3x harvest prices
So how much does it cost—and how much can you actually store?
📦 Onion Storage Capacity vs. Investment
| Storage Need | Required Volume | Approx. Floor Area* | Total Cost (USD) | Onions Stored |
|---|---|---|---|---|
| 100 metric tons | ～500 m³ | 160–170 m² (3m height) | 35,000 | 100 tons |
| 500 metric tons | ～2,500 m³ | 830 m² | 140,000 | 500 tons |
| 1,000 metric tons | ～5,000 m³ | 1,650 m² | 250,000 | 1,000 tons |
*Assumes standard stacking in mesh bags or crates with airflow gaps.
Onion density: ～200 kg/m³ (industry standard for ventilated bulk storage).
💰 Key System Requirements for Onion Storage
Unlike leafy greens or fruits, onions need cool + dry conditions:
- Temperature: 0°C to +4°C (ideal: 0–1°C)
- Relative Humidity: 65–75% RH (low humidity is critical!)
- Ventilation: Continuous low-speed airflow to remove respiration heat
- Insulation: 100–120mm PU panels (to maintain stable temp in hot climates)
- No condensation: Avoid frost or moisture on bulbs → prevents mold
⚠️ Never store onions above 5°C—sprouting accelerates rapidly.
❌ Never use high-humidity settings (like for tomatoes)—onions rot in damp air.
🌍 Real-World Insight
An onion growers’ union in Nashik, India built a 5,000m³ cold room to serve domestic and export markets:
- Total Investment: $ 225,000 USD
- Capacity: Stores 1,000 tons of red onions
- Result:
- Reduced post-harvest loss from 32% → 6%
- Supplied Dubai and Malaysia during local shortages
- Achieved ROI in 11 months
🔑 Why Onion Storage Is Different
Many suppliers mistakenly use standard fruit/vegetable cold rooms (85–90% RH). But onions are bulbs—not fleshy produce. They require:
✅ Low humidity (65–75%)
✅ Stable near-freezing temps (0–1°C)
✅ No ethylene exposure
✅ Proper curing before storage
For basic domestic sales, a well-designed chilled dry room is sufficient.
But if you’re targeting export markets or need to store onions beyond 3 months, consider upgrading to onion controlled atmosphere (CA) storage—which further suppresses respiration and sprouting by adjusting oxygen and CO₂ levels.
👉 Learn how onion CA storage extends shelf life to 3 months