Don’t store any thick-necked or soft bulbs, instead, use these up as soon as possible in your cooking.
A garage or unheated room in the house is an ideal location to store onions, somewhere they will be out of direct sunlight.
Individual onions can be placed carefully into netted bags, and you can use purpose-sold vegetable storage nets or netting sacks used to hold other fruit and veg, such as oranges.
The bags should also be hung off the ground, and you’re advised to check the nets periodically to remove any onions that have gone bad.
This process of curing and storing also works for other alliums, such as shallots and garlic.