Onions are a hardy ingredient which lasts a long time but if stored in the wrong place, they can cause other nearby produce to spoil or even go mouldy long before their expiration date. 

Sara Nelson, a cook and founder of Real Balanced has shared that onions need to be stored far away from potatoes as both can lead to faster spoilage due to how these foods interact. 

She said: “Onions, potatoes, bananas and many other fruits and vegetables emit ethylene gas, which speeds up the ripening process for nearby produce. Keeping these stored separately will extend their shelf life.”

The key to keeping onions fresh is storing them away from moisture and strong flavours as they are highly absorbent, and potatoes release too much water to store them together. 

Make sure to also keep onions away from root vegetables such as carrots which thrive in humid conditions, and instead store onions in a dry, well-ventilated area of your kitchen.

Onions need to be stored somewhere airy as they can trap moisture which can lead to them spoiling, which is why it is important to take them out of their supermarket plastic packaging. 

If you wish to avoid mouldy or squishy onions then store them in a basket, mesh bag or even an open paper bag which will all help keep moisture away from this delicious vegetable fresh.

Sara said: “Bins or boxes provide good air circulation as long as they are not packed too tightly. 

“Spacing is key; adequate room between onions ensures air can circulate freely, warding off potential moisture problems. This is crucial for preventing moisture buildup, which leads to mould and rot.”

It is also incredibly important to keep onions stored in the dark as bright light can trigger growth, which can lead to them sprouting and losing most of their flavour. 

Store onions somewhere dry, dark and with plenty of room such as a cupboard or drawer, but you can also hang onions somewhere in your kitchen as long as they are properly covered up.

Sara said: “Hanging onions is effective since it promotes excellent air circulation, reducing the risk of moisture buildup. 

“It also mimics traditional drying methods that have been used for centuries. It also allows for easy visual inspection, which is important for early detection of any issues. This method takes advantage of vertical space, which makes it ideal for someone with limited storage space.”

Just make sure onions are kept out of direct sunlight and covered with a mesh bag or netting to keep out light but also allow airflow. 

One clever old-fashioned trick was to store onions in tights or pantyhose as the mesh-like materials allow lots of air while also protecting them from the risk of mould or rot. 

Sara said: “Try knotting onions into the legs of the pantyhose and hanging them. Place an onion into the foot, tie a knot above it, add another onion and repeat. Cut below a knot whenever you need an onion.”

However, as long as onions are stored away from sunlight, potatoes and carrots, while also being kept in a dry airy space, then they can stay fresh for three to six months rather than lasting only a few weeks.