No, you can’t hear your plants scream

A new study published in late March revealed that plants emit a sound when under stress. 

This led to several news reports on the study with headlines indicating that plants 'scream', which led some VERIFY viewers to text us and ask if plants can be heard screaming when being cut, and Google Trends data shows people were searching: “Do plants scream?”

THE QUESTION

Can you hear your plants scream?

THE SOURCES

• “Sounds emitted by plants under stress are airborne and informative,” published on March 30 in the journal Cell
• Katherine Crowley, Ph.D, an assistant professor of plant biology at Unity College
• Richard Karban, Ph.D, a professor of entomology and ecology at the University of California in Davis
• Heidi Appel, Ph.D, a professor of environmental sciences at the University of Toledo

THE ANSWER

No, you can’t hear your plants scream

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WHAT WE FOUND

Plants do make sounds when exposed to distress, like if they aren’t watered or if they are cut, but these sounds aren’t audible to the human ear. So, when you cut into a plant or don’t water one for a few days, it’s not possible for a human ear to hear the sound it is making. 

That’s what researchers from India found after a six-year study on plants and a plant's response to stress. The study was published on March 30 in Cell, a scientific journal. 

During that six-year time period, the scientists took a batch of tomato and tobacco plants and monitored them for several days to see how the plants responded to different stressors – like if they weren’t being watered or if the plant’s stems were cut. The scientists wanted to know if they could hear anything when those stressors were applied.

They could, though not with their own ears. They had to use ultrasonic audio equipment to listen because the frequencies were so high they couldn’t be heard by a human. 

If the plant was left for several consecutive days without water, a popping sound could be heard. The longer the plant was kept without water, the more frequent the sound. If a plant was cut, a different frequency and duration of a sound was heard. If a plant wasn’t stressed at all — it didn’t make any sound.

There is a scientific explanation for the reason the plants were emitting sounds, Katherine Crowley, Ph.D., an assistant professor of plant biology at Unity College, told VERIFY.

Crowley said the sounds that the plant makes are a reaction to the way the water moves through the water-conducting parts of the plant. Richard Karban, Ph.D., a professor of entomology and ecology at the University of California in Davis, told VERIFY to think of the tubes in plants the way you think of pipes in your kitchen. 

Plants have tissue and tiny tubes that carry water. The water moves through the tubes, and then out through the leaves, so when there isn’t enough water, the long thin tubes have air bubbles in them and they can pop. This process is called cavitation.

“It's a natural process but always occurs in plants as they dry out. And it's highly possible that something to do with those air bubbles forming and popping, could be making the sound that we're detecting. So not an intentional thing that the plant is doing, but rather a sound that happens, because of the process of water movement and drying in the stem of a plant,” Crowley said.

When plants are cut, it interrupts the movement of water, as well, Crowley said. The stress is different because the water has to move differently through the plant when a portion of the plant’s waterway is removed. That’s why a different sound is made when plants are cut.

Heidi Appel, Ph.D., a professor of environmental sciences at the University of Toledo, also told VERIFY plants aren’t screaming — because, well… “they’re heartless.” They aren’t responding to emotions the way a human would if you sliced open your finger while cutting a tomato.

But, Appel said, these changes happening inside plants are all part of mother nature and the biology of plants. So, while we can VERIFY plants do make a sound when they are being cut, you can’t actually hear them screaming.