Start by separating the two crops
Onions and potatoes both keep best in a dry, airy spot, but they should not sit together in the same bag or bin. Potatoes are more sensitive to light, and onions are more likely to soften or mold if they are trapped with extra moisture.
Choose a cool, dark place that is still dry, then give each vegetable its own container. A wire basket, mesh bag, open crate, or paper sack with holes works better than a sealed bin. If your pantry is warm or damp, move the storage spot away from the stove, dishwasher, sink, or another humid area.
- Good setup: open basket for potatoes, mesh bag or shallow bowl for onions
- Avoid: airtight plastic bags, sealed drawers, and damp shelves
- Keep both away from fruit that gives off ethylene, such as apples and bananas
Store whole onions in dry airflow
Whole dry onions, especially yellow, white, and red onions, last longest with good ventilation and low humidity. Leave the papery skin on, trim only loose roots if needed, and do not wash them before storing. Moisture is the fastest way to shorten their life.
A cool pantry or cupboard is usually the best place for whole onions. Sweet onions are a little more delicate and can soften faster in a warm kitchen, so if your home runs hot, a perforated bag in the refrigerator is a short-term backup. Discard onions that are slimy, moldy or rotting; cooking does not make spoiled produce suitable to eat.
| Type | Best storage spot | What to look for |
|---|---|---|
| Yellow or white onion | Cool, dark pantry with airflow | Dry skin, firm bulb, no soft neck |
| Red onion | Cool, dark pantry with airflow | Tight skin, no mold around the stem |
| Sweet onion | Refrigerator if the kitchen is warm | Use before it wrinkles deeply |
| Cut onion | Covered container in the refrigerator | Use within a few days |
Sources: Iowa State Extension: Onions
Keep potatoes dark, cool, and dry
Whole potatoes keep best in a cool, dark, ventilated spot. A cool cellar or suitable refrigerator compartment can work; in a warm kitchen, buy smaller amounts and check them regularly. A paper bag, breathable sack, or open basket helps them stay dry and limits bruising. If potatoes sit on a counter or windowsill, light can turn the skins green and the flavor can become bitter.
Do not wash potatoes before storing them. Brush off loose dirt only. Keep them loose rather than packed under heavy produce bags, and check the batch once a week. Remove any potato that feels soft, smells musty, or shows mold so it does not spread to the rest.
- Store potatoes whole, unwashed, and out of direct light
- Do not use sealed plastic, which traps moisture
- Trim off small eyes before cooking, but discard potatoes with large green patches or heavy sprouting
Sources: OSU Extension: Storing potatoes
Handle cut, peeled, and cooked pieces separately
Once onions or potatoes are cut, the goal shifts from long storage to slowing drying, browning, and spoilage. Put cut onions in a covered container in the refrigerator as soon as you can, and use them within a few days for soups, sautés, or omelets. Their smell can spread to other foods, so keep the container sealed.
Peeled or cut potatoes should be submerged in cold water if you are not cooking them right away. Cover the container and refrigerate it, then cook the potatoes the same day when possible. For cooked onions or potatoes, let them cool quickly in shallow containers and refrigerate promptly.
- Cut onions: cover tightly so the aroma does not spread
- Peeled potatoes: cover with cold water and refrigerate
- Cooked onions or potatoes: refrigerate promptly in shallow containers
Sources: FoodSafety.gov: Cold storage chartFoodSafety.gov: Four steps to food safety
Spot problems early and save what is still usable
A little sprouting does not always mean the whole vegetable is lost. Onions with a firm, sound bulb and only a small green shoot can still be used after removing the shoot. Discard bulbs with soft rot, mold or slime. Potatoes with a few eyes are usually fine after trimming. What you do not want is a mushy texture, a sour or moldy smell, or large green areas on the skin.
If onions are shriveling, your storage spot is too warm or too dry, so move them sooner and use the oldest ones first. If potatoes are rotting at the bottom of the bag, the container is too tight or one damaged potato has spread moisture. Empty the basket, sort the batch, and repackage only the good pieces.
- Use firm, sound onions first when their outer skins are drying; discard mushy or rotting bulbs.
- Use wrinkled potatoes soon for mash, roasted chunks, or chowder
- Discard any vegetable that is moldy, leaking, or strongly off-smelling
Build a quick storage routine
The easiest way to keep onions and potatoes in good shape is to sort them the day you bring them home. Empty the bag, remove bruised pieces, and make two piles: one for onions and one for potatoes. Then choose containers that let air move. That one pass prevents forgotten produce from sitting at the bottom of a grocery sack.
Once a week, glance through both containers while you are unpacking groceries. Move any onion or potato that is starting to soften into the front of the line so you use it first. If you live in a very warm apartment, buy smaller quantities more often instead of trying to hold a large bag for weeks.
- At home: sort, separate, and remove damaged pieces right away
- Weekly: check for soft spots, sprouts, damp skins, or strong odors
- In hot kitchens: buy smaller amounts and use them more quickly
Common questions
Can onions and potatoes be stored together?
No. They keep better apart. Potatoes are sensitive to light and onions are more likely to soften in trapped humidity, so use separate containers and check each one weekly.
Should I refrigerate whole onions or whole potatoes?
Whole onions usually do best in a cool pantry with airflow. Whole potatoes usually do best in a dark, cool spot outside the refrigerator. Refrigerate cut onions and peeled potatoes instead.
What if my potatoes have green skin or sprouts?
Small sprouts or a few eyes can be trimmed away, but large green patches, mushy spots, or a strong bitter smell are signs to throw the potato out.
