Knowing how to store onions is the difference between selling top-quality produce for months or writing off losses every week. For a supermarket, wholesaler, or purchasing cooperative, every pallet of onions that sprouts, softens, or molds represents lost profit and a poor experience for the end customer.
In this guide, we’ll go over how to store onions in the warehouse and at the point of sale, how to prevent them from sprouting, and when it makes sense to freeze them. This is the same expertise we’ve been applying at Cebollas Aparici since 1975 to ensure our onions reach every customer in perfect condition.
How to store onions: The 4 key factors
The shelf life of dried onions depends primarily on four variables: temperature, relative humidity, ventilation, and light. If one of these factors is off, the others cannot compensate for it:
| Factor | Recommended range for dry onions | What happens if conditions fall outside the range |
| Temperature | 0–2 °C in cold storage (long-term storage); 20–25 °C only during curing | Between 5 and 20 °C, sprouting is encouraged; below −1 °C, onions may freeze and become damaged. |
| Relative humidity | 65–70% | Above 75–80%: root growth, mould and rot. Below 60%: dehydration and weight loss. |
| Ventilation | Constant air circulation between pallets and sacks | Stagnant air: condensation, heat build-up and localized areas of rot. |
| Light | Darkness or low light | Promotes greening and stimulates sprouting. |
How to store onions: Tips for maintaining their quality
The quality of an onion begins long before it reaches your kitchen or storage facility. At Cebollas Aparici, we take care of every stage of the process, from receiving and sorting the product to its storage and distribution, so that our professional customers receive onions in optimal condition.
- We inspect every shipment upon receipt. We check for firmness, a closed and dry neck, intact outer layers, and the absence of a musty odor. We set aside any onions that are soft, bruised, or moldy: a single onion in poor condition can contaminate those around it.
- We verify that the onions arrive properly cured. Curing is the drying of the neck and outer layers after harvest. A poorly cured onion has a damp neck, which is the main entry point for fungi. At Cebollas Aparici, the product leaves the warehouse already cured and sorted.
- We sort them by variety and intended use. Not all onions have the same shelf life. Those with firm skin and higher dry matter content, such as the Grano de Oro onion or the Red onion, tolerate longer storage than Sweet onions or Spring onions, which must be rotated quickly.
- We adjust the chamber before the product is loaded. Stable setpoint temperature (0–2 °C for long periods) and relative humidity of 65–70%.
- We use breathable containers: mesh bags, open-sided boxes, or ventilated pallets. Never use sealed plastic bags or stretch film that prevents air circulation.
- We arrange the products with space for air circulation. We keep pallets away from walls and the floor and leave aisles between rows. We limit the height of stacked sacks to avoid crushing the lower layers.
- We separate onions from other products. We avoid storing them next to potatoes, which add moisture, and next to fruits that release ethylene, such as apples, pears, or bananas. In addition, onions transfer their odor to sensitive products.
- We strictly follow FIFO (first-in, first-out) rotation. The first items to arrive are the first to be shipped out. We label each batch with its arrival date.
- We check inventory weekly. We look for sprouts, roots, soft spots, and odor. Removing a few units early on prevents the loss of an entire pallet.
How long do onions last when stored properly?
As a general guideline, well-cured dry storage onions last several months in cold storage at 0–2 °C, and slightly less time in a dry storage area at room temperature. Sweet onions and seasonal onions (new or tender onions) have a much shorter shelf life, measured in weeks, so it’s best to adjust orders based on actual shelf turnover. The exact shelf life depends on the variety, the curing process, and the stability of storage conditions.
How to store onions to prevent sprouting
To prevent onions from sprouting, they must be kept in a dormant state: at a stable cold temperature near 0 °C or, failing that, in a dry, temperate environment without temperature fluctuations, always in the dark. Sprouting is the leading cause of loss of commercial value in storage, because the onion depletes its reserves, becomes soft, and loses flavor.
Why onions sprout
After harvest, onions enter a natural dormant period. When that period ends, any favorable stimulus reactivates growth. There are three common triggers: moderate temperatures (5 to 20 °C), high humidity, and sudden temperature changes that cause condensation.
Effective measures against sprouting
To prevent onions from sprouting, it is essential to maintain a constant temperature between 0 and 2 °C, avoid sudden changes in temperature, keep humidity below 70%, and store the product in the dark with adequate ventilation.
It is also important to choose storage varieties with a longer dormancy period and to ensure rapid turnover in the store, restocking small quantities frequently to maintain quality and extend the product’s shelf life.
What to do with an onion that has already sprouted?
An onion with a sprouting shoot is still safe to eat, although it loses firmness and sweetness and is not marketable as a prime product. In the foodservice industry, it can be used immediately in sautéed dishes or stock. In supermarkets, it is recommended to remove it from the shelf and inspect the entire batch, as this is usually a sign that storage conditions have become unsuitable.
Common mistakes in storing onions in warehouses and stores
Most onion shrinkage is not due to the product itself, but rather to repeated handling errors. These are the most common errors in supermarkets and wholesale warehouses.
| Error | Consequence |
| Spraying water on the display shelf, as is done with leafy vegetables | Root growth, mould and stained outer skins within a few days |
| Displaying onions in sealed plastic bags | Internal condensation and rotting |
| Storing them next to potatoes or fruit | Increased humidity, ethylene exposure and odour transfer |
| Repeatedly removing products from and returning them to cold storage | Breaking dormancy and triggering sprouting |
| Stacking sacks without allowing air circulation | Heat build-up in the centre and crushing |
| Replenishing large quantities of stock at once in the store | Products remain exposed to room temperature and light for several days |
| Failing to check stock regularly | One rotten onion can cause the entire batch to spoil |
Best practices on the shelf
At the point of sale, onions should be placed in a dry, shaded area, away from the misting system for fruits and vegetables. It’s best to display smaller quantities and restock more frequently, removing any onions with sprouts, bruises, or loose skin daily. A clean, uniform display conveys freshness and reduces customer handling, which can also damage the product.
Proper storage starts with proper purchasing
Storing onions without compromising quality depends on four key factors: stable cold temperatures, controlled humidity, good ventilation, and disciplined inventory turnover. However, no storage facility can correct for an onion that was improperly cured or poorly selected at the source.
At Cebollas Aparici, we have been exclusively dedicated to the wholesale sale of onions since 1975. We select each batch, oversee the curing process and logistics, and work with more than 10 varieties so that every customer can choose the one that best fits their inventory turnover and intended use. Additionally, we are the first company in Spain to offer certified residue-free onions thanks to ZERYA® certification.
Do you need an onion supplier to help you reduce waste? Check out our varieties or contact our sales team directly.
