Storing potatoes and onions together in the pantry could be shortening their shelf life: a Spanish pharmacist, Álvaro Fernández (known online as @farmaceuticofernandez), argues that they should always be kept separate to avoid germination, softening and early rot, due to ethylene and humidity.
The recommendation was publicized on social media and replicated by media such as the Spanish portal La Razón, which draws attention to a common habit: arriving from a purchase and putting everything in the same drawer, without thinking about the consequences.
The logic, according to the pharmacist, is simple: onions release ethylene (a natural gas associated with maturation) and potatoes are sensitive to this environment, which can accelerate germination; Furthermore, the moisture released by the potatoes can create a “microclimate” that favors mold and deterioration of the onions when they are left lying around.
Ethylene is widely described as a gaseous plant “hormone”, capable of influencing maturation and aging processes in fruits and vegetables, and is therefore a relevant factor when deciding what can (or cannot) be stored together.
In practice, this means that not all foods “like” the same environment: some tolerate ethylene well, others accelerate unwanted changes when exposed to it, such as changes in texture, flavor or the beginning of sprouts.
That’s why the golden rule at home tends to be pragmatic: separate potatoes from onions and, whenever possible, keep potatoes away from other ethylene producers (like apples or bananas), especially when you want them to last several weeks.
How to store potatoes to last longer
For potatoes, the most repeated recommendation is: a cool, dark, dry and well-ventilated place. A paper bag, cardboard box with openings or an airy basket usually works better than plastic bags, which retain moisture.
Avoid placing them next to the stove, oven or in very hot areas of the kitchen: heat and light facilitate degradation and can accelerate germination. It also helps to do a weekly “sorting” and remove those that are getting soft so they don’t contaminate the rest.
And if a potato is already very soft, has a strange smell, extensive stains or clear signs of deterioration, the safe option is to discard it — the idea here is to stop waste, but without “saving” what is no longer of quality.
How to store onions without spoiling them
Onions prefer a cool, dry place with good air circulation, ideally in a mesh bag or open basket; The aim is to prevent condensation and trapped moisture, which accelerates rot.
According to , here, the most important “no” is the same: no closed plastic bags and no keeping them close to the potatoes, especially in small spaces like drawers or baskets without ventilation.
If the onion is cut or already peeled, then it makes sense to store it in the refrigerator, but in a closed container, to limit odors and reduce contamination.
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