How To Keep Frost Off Your Windshield Using A Potato Or An Onion

Waking up to a windshield coated in frost isn't just annoying, it can throw off your whole morning. Scraping ice in the freezing dark is nobody’s idea of a good start. But there’s a surprisingly simple trick that can save you the hassle. You might already have what you need in your kitchen. It turns out, common vegetables like potatoes and onions can help keep frost from forming on your windshield. Here’s how it works.

Why Potatoes and Onions Work

A bunch of potatoes next to a bunch of onions.
Photo Credit: Canva Pro
Photo Credit: Canva Pro

Potatoes and onions both contain natural sugars and moisture-resistant compounds. When rubbed across glass, they leave behind a thin film. That layer acts as a barrier between the cold air and your windshield. It slows down how quickly moisture sticks and freezes. This isn't magic, and it won’t stop a blizzard, but it can prevent the kind of light frost that forms overnight when temperatures dip just below freezing.

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How to Apply Them Properly

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A hand rubbing a cut potato on a car windshield.
Photo Credit: News18
Photo Credit: News18
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To try it, slice a raw potato or onion in half. Before the cold sets in, ideally in the evening, rub the cut side firmly across the entire windshield. Focus on spreading the natural film evenly. You don't need to scrub or press too hard. Let the juice coat the surface, then walk away. There’s no need to rinse or wipe it off. In the morning, you should notice little or no frost on the treated area.

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Which One Should You Use?

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A hand holding up a cut onion.
Photo Credit: Natural Home Tricks
Photo Credit: Natural Home Tricks
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Between the two, potatoes are usually preferred. They're less pungent and tend to leave a clearer residue. Onions work too, but they can make your car smell a bit sharp if you use them regularly. Still, in a pinch, either one will help. If you’ve only got an onion lying around, it’s better than scraping ice the next day. Just be sure to air out your car if the scent lingers.

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Does It Damage the Windshield?

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A frosty windshield.
Photo Credit: Canva Pro
Photo Credit: Canva Pro
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This method is safe for most car windshields. The natural juices won't harm glass or factory sealants when used occasionally. However, it’s not recommended every single day for months. Over time, the sugars can build up and attract dirt. To avoid that, give your windshield a good clean once a week if you’re using this method regularly. That keeps things clear and prevents streaking from leftover residue.

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When This Trick Works Best

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A hand rubbing a cut potato on a car windshield.
Photo Credit: Family Handyman
Photo Credit: Family Handyman
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This isn't meant for extreme winter weather. If snow or freezing rain is in the forecast, you’ll still want to cover your windshield or park indoors if possible. The potato or onion trick is most helpful on chilly, dry nights when you’d otherwise wake up to a thin, annoying frost. It’s especially useful for people who don’t have time to defrost their car in the morning or live in areas with milder winters.

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Don't Forget the Wipers and Mirrors

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A frosty windshield.
Photo Credit: Canva Pro
Photo Credit: Canva Pro
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While your windshield is the main concern, it helps to run the cut potato or onion over your side mirrors and even your wiper blades. These smaller parts also collect frost, and clearing them manually takes extra time. A quick swipe can make a difference. If your wipers freeze to the glass, it can damage the rubber or even your wiper motor.

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A potato or an onion might not seem like tools for winter car care, but they can make frosty mornings more manageable. This trick is easy, affordable, and surprisingly effective when used the right way. It won't fix every winter problem, but it’s a smart way to get ahead of one. Try it next time frost is in the forecast and see how much easier your morning routine can be.