Why You Should Never Store Potatoes With Onions

Whether you buy potatoes and onions a few at a time or in 10-pound bags, where you put them once home matters. I grow enough potatoes and onions to last the entire winter, so I care as much about storage as about bed preparation and harvest.

It’s frustrating to reach into their box and find they’ve sprouted or, worse, softened with rot. Temperature, airflow, and light affect their longevity. But above all, there’s one thing to remember: You should never store potatoes with onions.

Why Potatoes and Onions Are Not Good Neighbors

Onions emit lots of ethylene, a natural gas that speeds up ripening of many fruits and vegetables. Add an apple or banana to a paper bag of avocados, and watch how quickly ethylene works.

When you intermix onions and potatoes, especially in plastic bags, the gas encourages sprouting and softening. Moisture, light, and warmth also trigger sprouting. Essentially, potatoes and onions react to these spring-like conditions and start to grow.

This makes your kitchen counter one of the worst places to store potatoes and onions. Stoves and dishwashers pump out heat and humidity, and light (the culprit behind green potatoes) spills into far corners. Separate and consistently dry, dark, cool conditions keep these vegetables firm and edible longer.

It’s hard to pinpoint the ideal storage distance, but the farther apart, the better. In a cool, airy pantry, the ethylene from onions in a wire basket on the topmost shelf might not seep down to a towel-draped box of potatoes on the floor. If you have a cramped, stuffy pantry, opt for separate drawers or cupboards.

Both vegetables keep best between fridge and cool room temperatures, so I store onions and potatoes outside my kitchen. In my mudroom, repurposed ice chests lined with wooden slats to hold potatoes, and a towel over the open top blocks light. I also have friends who pile potatoes on open egg cartons in a cracked-open drawer or in wooden crates in a rarely used guest room or garage.

I store onions in a single layer in shallow, perforated produce boxes stacked in a cool, windowless corner. My sister keeps onions in their mesh bag in a dry basement room. Onions also store well in hanging mesh bags in an unused coat closet or wire baskets on a shelf under an interior staircase.

To store these root vegetables as long as I do, buy them directly from local growers, if possible. Potatoes and onions sold in supermarkets are often harvested early, warehoused for months, and exposed to temperature and light swings. Small local farms are more likely to grow, harvest, and cure these vegetables with the same care I give homegrown varieties I’m still eating in spring.