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You might have heard that plants do better with a bit of verbal encouragement. The idea that plants like being talked to is an old one—there’s mention of it in a book published in 1848.

And it sort of seems plausible: When you talk, you send both sound waves and carbon dioxide into the air, either of which could affect plants. But although scientists have had more than a century to investigate whether talking to plants helps them grow, no one has answered the question directly. With the data we have it’s more a... maybe?

And there are probably easier ways to perk up your houseplants. We know that at least some plants can "hear" us talking in the sense that they respond to sound waves with frequencies in our vocal range— roughly between 50 and 500 hertz, or vibrations per second. Botanists have found that plants tend to grow better and seeds germinate faster when played recordings of talking or classical music.

They think plants react to these noises because they’re tuned to pick up changes in wind or vibrations from animal movement, which, like sound waves, push on the plants' cells. And they have seen increases in growth hormones and changes to gene expression in plants played music or single-note tones. The trouble with comparing these studies to talking is that they often play the sounds at loud volumes or for long periods of time—like, hours—so it’s hard to know what the effects of a normal conversation would be.

The recorded aspect also means these experiments can’t tell you anything about whether your breath itself matters. And that’s a shame, because it’s possible that the CO2 you exhale at your ficus works like a kind of airborne fertilizer. Plants are able to convert carbon dioxide and water into sugars, which, like us, they need as biological fuel.

When CO2 rises, there’s more carbon available, so they can make more fuel. When you exhale, your breath contains about a hundred times more carbon dioxide than the air you breathed in, but it also immediately begins mixing with the surrounding air. So talking to your plant, even right up close, might not change the carbon dioxide levels around it enough to matter.

We don’t know because no one's ever tested it. The overall lack of data makes it hard to say for sure whether talking to your plant has any effect at all. Though there are tons of people who swear by it.

Some experts have a simpler explanation for why house or garden plants that are talked or sung to tend to do better. If you’re stopping to chat up your plants, you’re probably paying closer attention to them. So you’re more likely to notice that they need water, or aren’t getting enough light, or are being attacked by pests.

After all, as anyone who’s ever forgotten a cactus on their desk until it’s dry enough to catch on fire will tell you, remembering to take care of your plants is most of the battle. Thanks to Patreon patron Kendra for asking! And thanks to all the other patrons who voted for this question in our monthly poll.

If you’d like to submit a question to be answered or vote on which questions we answer, you can head over to patreon.com/scishow. ♪ OUTTRO ♪.