Gardeners have speculated for many years about whether or not talking to plants will help them to grow. Surprisingly, though scientists have not reached a strong conclusion, there is mounting evidence to suggest that sound waves, whether from our voices or from music, may indeed help plants grow strong. Will plants in a polytunnel grow better if you talk to them? The answer seems to be a resounding – maybe. Intriguingly, we just don't know. But since we don't know, perhaps it could be argued that it certainly won't hurt to try!
Studies have suggested that female voices may stimulate plants to grow better than male voices, and that the expulsion of carbon dioxide in the direction of plants may have something to do with positive results, though also seem to suggest that the content of what we say has little bearing on how well a plant thrives. Plants, it seems, do just as well when showered with insults as when showered with kindly words and praise. Surely though, we don't want to be mean?! When it comes to the carbon dioxide theory, it seems this could only ever be a partial explanation, since music or speech played through speakers can also have an impact, it seems, on plant growth.
What we do not for certain is that plants can 'hear' – not in the same way as us, of course – they have no ears. But plants can 'hear' sound vibrations. Sound is a stimulus for plants, and so, of course, it is an environmental factor, like how much sunlight a plant gets, or how much water is available. Since, then, we can say that sound is an environmental factor, we know that it can affect plant behaviour and cause physiological change. So, in theory, speech should act on plant growth – we just don't know exactly why, or how.
A recent study found that certain plants responded to the sound of a caterpillar eating its leaves by releasing a chemical defence. Scientists recorded the caterpillar munching. When they then played back the sound (without letting loose the caterpillar), the plants produced the same chemicals in response to the specific sound vibrations.
There is a lot more to plant communication that we do not yet know, but the more we discover about plants, the more sophisticated we realise that they are. While there is no conclusive evidence that talking to plants helps them to grow, I would argue that it is a good idea to try.