Onion Storage Systems for Hot and Humid Climates

Onion Storage: How to Keep Your Harvest Fresh and Profitable All Year Round?

Maximizing onion shelf life starts with the right storage design and a precisely engineered microclimate system.
A properly ventilated facility minimizes post-harvest losses and preserves the product’s original quality, color, and weight - ensuring your crop remains market-ready even months after harvest.

Agrovent solutions are designed to work effectively across diverse climates - from the hot, dry conditions of Saudi Arabia to the humid regions of India and tropical Africa.

Four Key Stages of Onion Storage

1. Drying (Curing Phase)

The first and most critical stage for onion preservation is thorough drying.
Freshly harvested onions retain a high level of internal moisture. This moisture must be removed quickly to prevent neck rot and bacterial infection — especially in warm or humid environments.

At this stage:

• Warm, dry air (2–3 °C higher than bulb temperature) is supplied evenly through the ventilation system.
• Product temperature is gradually increased up to 20 °C, promoting moisture evaporation.
• When onions are harvested green or under wet conditions, the drying air temperature can be safely raised to 30 °C to accelerate the process.
• Avoid keeping the product between 22 °C and 25 °C, as this range encourages neck rot development.
• Continuous ventilation for 8–9 hours daily during the first 6 weeks ensures effective curing.
• After that, 4 hours of daily air exchange is sufficient.

2. Temperature Equalization

Once the outer layers are dry, onions must continue ventilating with either inside or outside air to ensure even drying throughout the pile or container.
Air capacity should be 200–250 m³ per ton of stored product.
This prevents fungal growth and maintains consistent quality before long-term cooling begins.

3. Gradual Cooling

After the curing phase, the product temperature should be slowly reduced — by no more than 0.5 °C per day — until it reaches around 20 °C. During the day, when relative humidity is lower, cooler outdoor air (3 °C below the bulb temperature) is used for ventilation. At night, short ventilation cycles of 10–15 minutes every 3 hours prevent condensation and maintain air balance.

4. Long-Term Storage

After two weeks of stabilization, cooling systems can be switched on.
The ideal storage conditions are:

• Temperature: 0 °C to +1.5 °C
• Relative humidity: around 75 %
• Uniform airflow: to avoid temperature gradients within the pile

A stable microclimate prevents sprouting, dehydration, and decay — allowing onions to remain fresh for up to 9–10 months with minimal losses.

Agrovent cooling and ventilation systems designed to automatically maintain these parameters, adapting to local climate and energy conditions. Whether you operate in a tropical, arid, or variable climate, Agrovent ensures reliable performance and extended storage life for your onions.

Why Choose Agrovent for Onion Storage

• Up to 40 % reduction in post-harvest losses
• Long-term storage — up to 10 months in stable condition
• Full climate automation — temperature, humidity, CO₂ balance
• Custom design for local conditions — India, Middle East, Africa
• Energy-efficient and easy to operate