Houseplants actually do something incredibly disturbing when they are severely dehydrated or have their leaves cut.

A stressed plant can make sounds you cannot hear

When some plants are severely dehydrated or have stems cut, they emit tiny airborne clicks in the ultrasonic range—frequencies too high for human ears. Sensitive microphones can detect them, and recordings can contain patterns that differ between types of stress. The unsettling image of a plant “screaming” is catchy, but these sounds are not cries or deliberate signals in the human sense.

The sound comes from water under tension

Inside a plant, water travels upward through narrow tubes in the wood called xylem. Evaporation from the leaves helps pull that water along, much as a drink rises through a straw. During drought, the pull grows stronger. Air bubbles can form in the water column, and their formation or collapse can produce vibrations that travel through the plant and into the air. Cutting a stem also disrupts the water system and can create similar physical stress.

This process, called cavitation, is a mechanical consequence of water moving through a strained transport system—not evidence that the plant feels pain. The sounds are one clue to what is happening inside, much as a crackling pipe can reveal a problem without having anything to say about it.

A sound can reveal stress without being a message

Because the clicks are too high-pitched for people to hear, researchers use specialized recording equipment to study them. If sound patterns can reliably distinguish conditions, they may eventually help monitor plant stress without cutting into the plant. For now, the striking takeaway is simpler: a plant under strain can make a detectable sound even when the room seems completely silent.