10 Produce-Storage Myths and Facts (Which Foods Can Share Space?)

An onion makes about a thousandth of the ethylene a ripe kiwi does, and half the internet still blames onion gas for your sprouting potatoes.

Quick setup. Ethylene is an odorless, colorless gas that ripening fruit gives off, and it still works in the fridge, just slower. It’s the villain in every “never store these together” list you’ve ever scrolled past.

Those rules are mostly right. The reasons you were given are mostly wrong. Ethylene-induced carrot bitterness is a quality effect, but bitterness alone doesn’t tell you whether a carrot is otherwise sound.

Here are 10 produce-storage myths and facts, from neighbors worth separating to ripening tricks and foods with fewer ethylene concerns.

1. Onions + Potatoes

Keep the rule. Drop the gas story.

USDA’s commercial storage handbook puts onions at 0.1 microliters of ethylene per kilogram per hour, which it calls “very low.” Tomatoes run 1 to 10 on that scale and a ripe kiwi hits 50 to 100. Potatoes, for their part, are “not very sensitive to external ethylene” anyway.

It gets better. Ethylene is sold commercially to STOP sprouting in both crops. A potato-storage project at Cranfield University in the UK reported “excellent sprout inhibition” under ethylene, and a 2009 paper in Annals of Botany called it “a powerful inhibitor of sprout growth in onion bulbs.”

So why split them up at all? Air. Potatoes want cool, moist air at 80 to 90% humidity, and onions want cool, dry air at 50 to 60%, which is how University of Idaho Extension draws the line.

Put them in one bin and somebody’s getting the wrong weather. High humidity makes onions grow roots and rot.

Also, onions stink. They shouldn’t sit next to anything that soaks up odors.

2. Apples + Potatoes

This one runs backwards.

The old root-cellar rule says fruit like apples makes potatoes “sprout early.” Then people tested it. In a 2023 master’s thesis at the University of Limpopo, potatoes stored with apples for 30 days at about 73°F sprouted significantly less than potatoes stored alone.

In one batch, every single potato stored alone sprouted. The best apple-stored batch came in at 18%.

Weirdly, both sides have a point. A 1974 paper in Plant Physiology found ethylene does two opposite things to a potato. It wakes it up sooner, then stunts the sprouts.

So it cuts both ways. Pairing apples with potatoes doesn’t inevitably speed up sprouting and may slow the sprouts under some conditions, but it’s not a guaranteed hack, and the apple-stored potatoes in that thesis lost some starch.

The actual loser is the apple. Potatoes can make apples taste musty.

3. Apples + Carrots

Nearby ethylene-producing fruit can make otherwise sound carrots bitter. That doesn’t mean every bitter carrot got that way from fruit exposure.

In storage tests, ethylene at roughly 0.2 parts per million makes carrots build a bitter compound called isocoumarin. It’s a natural defense chemical. Cornell Cooperative Extension explains the ethylene-triggered buildup of isocoumarin and advises keeping carrots separate from apples.

My favorite detail in this whole list: peeled carrots don’t turn bitter from ethylene. The bitterness builds in the peel.

Parsnips do the same thing. And it isn’t only apples, because pears and ripe tomatoes are gas-makers too.

If you’ve read that carrots “absorb odors” from apples, that’s the wrong mechanism. Right rule, wrong reason, again.

4. Tomatoes + Cucumbers

Cucumbers can’t win.

They make little ethylene themselves but are “very sensitive to it,” and in storage tests 1 to 5 parts per million speeds up yellowing and decay. University of Minnesota Extension doesn’t soften it: “Do not store with apples or tomatoes.”

So you move them to the fridge, right? Cucumbers get chilling injury below 50°F after 2 or 3 days. Too cold in the fridge, gassed on the counter.

Peppers and eggplant belong in the same warning. Purdue says to keep peppers away from ripening tomatoes and cantaloupes.

5. Bananas + Broccoli

Broccoli is “extremely sensitive.” In storage tests, ethylene at 2 parts per million at 50°F cut its shelf life in half, and the symptom is yellowing florets.

It runs in the family. Brussels sprouts yellow and drop leaves, and cabbage “should not be exposed to ethylene after harvest.”

The rest of the green stuff isn’t thrilled either. Lettuce gets rusty brown spots, leafy greens yellow faster, and green beans lose 30 to 50% of their storage life at levels above 0.1 parts per million in storage tests.

Who’s doing the gassing? Ripe bananas, apples, pears, avocados, cantaloupes, peaches and ripe tomatoes are the heavy producers. So, the entire cast of a nice-looking fruit bowl.

6. The Fruit Bowl + Kiwi

Kiwi is extremely sensitive to ethylene. In storage tests, as little as 5 to 10 parts per billion can speed up softening without the rest of ripening keeping pace.

Billion, with a B. What you get is fruit that’s soft before it’s sweet.

Then the kiwi switches sides. Its own ethylene output jumps from about 0.1 to 0.5 at harvest to 50 to 100 when ripe, roughly a hundredfold in the same fruit. A kiwi’s own ethylene production rises sharply as it ripens.

7. Apples + Winter Squash

Apples can turn a green squash orange. Dark green squash like Hubbard shouldn’t be stored near apples because the ethylene can turn the skin orange-yellow, and that finding dates to 1945. Green zucchini can yellow too.

8. Green Onions + Mushrooms

No ethylene here at all. Mushrooms absorb odors from green onions, and USDA’s handbook says the two “should not be transported or displayed together.” That’s how you end up with mushrooms that taste like scallions.

Mushrooms get it from both sides, because ethylene from fruit browns the caps. One neighbor ruins the look, the other ruins the taste.

Okra has the same weakness, by the way. It traps odors from melons, onions and potatoes.

9. Bananas + Avocados in a Bag

The mechanism is real. Unripe avocados are “very sensitive to ethylene.” But commercial ripening uses 10 to 100 parts per million for roughly 12 to 72 hours.

A grower ran a side-by-side at home in 2026 with 15 avocados in three groups of five. Open basket, closed box, closed box with a banana and an apple, all around 73°F.

All three ripened on the same timeline. He points to temperature as the main driver.

That’s one test, one variety, and a box and not a paper bag, so call it a careful home test that found nothing, not settled science. That experiment gives no reason to count on extra fruit speeding things up.

10. Foods With Fewer Ethylene Concerns

Some foods are less sensitive to ethylene, but their storage needs still count.

Garlic and onions can share cool, dry storage with good ventilation. Garlic makes very little ethylene, isn’t sensitive to it, and both like dry air.

Strawberries and grapes have relatively few ethylene concerns, though both still have disease-related caveats. Sweet potatoes at normal ventilation make ethylene “a relatively minor concern,” and for sweet corn, outside ethylene “normally is not a problem.” These foods still need suitable temperatures, humidity and ventilation, so low sensitivity doesn’t make every neighbor a good fit.

Give Your Produce Better Neighbors

Ventilation helps keep ethylene from building up, but it can’t fix mismatched humidity needs or odor transfer. Choose compatible neighbors and the temperature and humidity each food needs, rather than treating an open counter as a cure-all.

Penn State’s fix is almost boring. Put the sensitive produce in paper bags, roll them shut, and give them one crisper. Bag the heavy gas-makers and use the other crisper.

Damaged fruit puts out more ethylene too, so “one bad apple” was never a metaphor.

Your onions were framed.