Onions – a vegetable crop widely grown across Europe. This vegetable is used year-round in countless culinary dishes. Many home cooks and gardeners are interested in how to store their harvested onions for as long as possible.
In this article, we will discuss whether onions can be stored in a cellar during winter and how to do it correctly.
Table of contents
Optimal Conditions for Storing Onions in Winter
To preserve onions until the next season, it is necessary to create optimal storage conditions – the right temperature and humidity for long-term preservation.
Important! The key requirement for storing onions is proper ventilation in the storage area. Poor ventilation or lack of airflow in a humid environment will cause the bulbs to rot quickly.
The ideal humidity level should be between 75-80%. Higher humidity will cause the bulbs to sprout roots, affecting their taste and culinary quality.
If the onions become damp due to excess moisture, they should be moved to a dry area, dried, and then returned to storage.
If humidity is too low (below 75%), the onions will dry out.
The storage temperature should be kept constant at 0…+3°C. The outer onion skin provides some insulation, so minor temperature drops are not harmful – this mainly applies to pungent varieties. Red and sweet onions are more sensitive to cold.
Higher temperatures will cause the bulbs to sprout, leading to rot.
Stored onions should be kept away from light, as exposure will trigger green shoot growth.
How to Prepare Onions for Storage
About a month before harvesting, stop watering the plants to prevent excess moisture absorption.
Note: Underripe or overripe bulbs have a shorter shelf life.
Choose a dry day for harvesting. Onions picked in rainy weather are more prone to premature rotting.
Avoid pulling onions forcefully from the ground – this can damage the bulbs and reduce their storage potential.
Gently loosen the soil with a spade, then remove any remaining dirt. Do not drop the bulbs on hard surfaces, as bruises will lead to spoilage.
Spread the harvested onions in sunlight or a dry indoor space for 10-14 days to dry. This allows moisture between the layers to evaporate.
After drying, trim the leaves, leaving 5-7 cm of the neck.
Before storage, sort the onions by variety and size. Early and sweet varieties have a shorter shelf life (until February) and are more prone to disease. Pungent varieties stay fresh until the next season. Winter onions store less effectively than spring-planted ones.
Select only healthy, firm bulbs without damage and with dry stems. Sort them by size and store in separate containers.
Rules for Storing Onions in a Cellar or Basement in Winter
Small quantities of onions can be stored at home, but larger harvests require a cellar or basement. Proper conditions will help retain nutrients and vitamins.
Preparing the Storage Space
The storage area must be properly prepared. Clean thoroughly and disinfect all surfaces.
The cellar should be dry and spacious enough to allow proper air circulation. If space is limited, install shelves or racks lined with paper or burlap.
Important! If winter temperatures drop too low, insulate the walls.
Proper ventilation is essential to prevent rot.
Compatibility with Other Vegetables
Onions should not be stored with most other vegetables. Most vegetables and fruits require humidity above 85%, which will cause onions to rot.
Storing onions with potatoes is particularly problematic, as the potatoes release moisture that spoils the bulbs.
Acceptable storage partners include pumpkins and garlic, as they have similar requirements. Pumpkins need +4…+10°C and 80% humidity, while garlic prefers –3 to +3°C at 80% humidity.
Storage Duration
Under ideal conditions, onions can last 8-9 months. White and red varieties typically store for 3-4 months, while sweet varieties like the Spanish onion last 4-5 months. After this, sprouting begins.
Storage Methods
Several storage methods are commonly used: wooden crates, cardboard boxes, fabric bags, mesh bags, and braids.
Regardless of the method, check the onions periodically and remove any soft, sprouted, or rotting bulbs to extend shelf life.
Plastic and Wooden Crates
The most common method is storing onions in plastic or wooden crates. The crates should be no taller than 50 cm, as deeper layers may get crushed. Ensure proper ventilation by using crates with side openings.
Place the crates on shelves or pallets to avoid moisture buildup at the bottom. Leave space between crates and walls for airflow.
Stacking crates saves space.
Note: Ensure air can circulate around all sides of the crates.
Fabric Bags
Fabric bags are another good option. Use small bags to keep the onion layer no thicker than 30 cm.
Tip: Large bags increase the risk of spoilage in the bottom layers.
Choose breathable natural fabrics like cotton or jute. Avoid synthetic materials, as they trap moisture.
Store filled bags on shelves or hang them from ceiling hooks.
Mesh Bags or Tights
Some people use mesh bags or even nylon tights for storage. These materials allow excellent airflow and moisture evaporation.
Fill the bags with 2-3 kg of onions and hang them from the ceiling or hooks, spacing them 25-30 cm apart. Keep them at least 50 cm from damp walls.
For extra protection, tie a knot between each bulb to isolate them. This prevents spoilage from spreading.
Egg Cartons
Cardboard egg cartons work well for small to medium onions. The cardboard absorbs excess moisture.
Place one bulb in each compartment. Stack filled cartons on shelves.
Braids or Bundles
Braiding onions is a traditional and effective storage method. Dry the leaves just enough to remain flexible – overly dry leaves will crumble.
Tip: Use onions of similar size for even braiding.
Two braiding methods:
- Use twine or rope folded in half. Tie an onion at the midpoint, then braid by adding one bulb at each turn. Keep the leaves tight for secure placement. A typical braid holds 30-35 bulbs. Finish with a loop.
- Alternatively, tie pairs of onions together first. Then attach them to a central rope, alternating directions with each addition. Knot the rope after each pair to secure the braid.
Braiding allows maximum airflow and easy inspection. Spoiled bulbs can be removed without disturbing the rest. Braids also save space by hanging vertically.
How to Prevent Onion Rot in Cellar Storage
Sometimes, stored onions develop an unpleasant odor due to improper conditions.
Common onion diseases:
- Neck rot – a fungal infection starting at the neck, then spreading as black spots.
- Bacterial rot – internal decay with alternating healthy and rotten layers.
- Fusarium – root rot with white mold spreading upward.
Rot can also result from pests like stem nematodes or root mites.
To reduce infection risk, treat bulbs before storage with a biofungicide like Serenade® ASO.
Late-maturing varieties store best. Onions grown from treated seeds and rotated properly in crop cycles also last longer.
Select only healthy, undamaged bulbs with golden-brown skin for storage. Regularly inspect and remove spoiled onions. Maintain proper temperature and humidity, and use well-ventilated containers.
To prevent moisture buildup, layer onions with wood shavings or ash (200 g per 10 kg of onions).
Avoid overpacking containers and never use plastic bags, as condensation will cause rot.
Storage Tips and Tricks
Useful storage hacks:
- Sprinkle crushed chalk (250-300 g per 10 kg) to absorb excess moisture.
- Place containers of lime in the cellar to reduce air humidity.
- Leave onion skins in storage – they absorb moisture.
- Coat the base of bulbs with clay to prevent sprouting.
- Wicker baskets or mesh bags allow excellent airflow.
Conclusion
A cellar is the best place to store onions long-term. Proper conditions allow onions to stay fresh all winter, whether in crates, fabric bags, or hanging braids.
The key is choosing the right variety and maintaining ideal storage conditions.