I. Do Plants Like Music?
History is filled with a surprising number of humans who wondered if plants like music. But just asking this is ill-advised anthropomorphizing. Plants lack eardrums and cerebral cortexes. With rare exceptions, like mosses and liverworts, plants are rooted to the ground. Earless organisms that can take all day to move a few centimeters will have a very different relationship to time, space, and sound than humans.
Yet plants are not deaf. Increasing evidence shows that at least some plants sense and emit sound. Corn seedlings pop and click in response to specific frequencies. Certain flowers only release pollen in the presence of a bee’s buzz or an artificial approximation of it. The roots of pea seedlings move toward the sound of flowing water, even in the absence of actual moisture. While this is all quite fascinating, we should resist trying to translate these activities into human terms.
Of course, it is difficult not to project ourselves onto plants that respond to sound. And sometimes, it’s difficult not to project ourselves whether the plants are actually responding or not. In the late 1960s, Dorothy Retallack, a music student completing a required biology course, conducted an experiment seemingly showing that rock music kills plants and classical music makes them grow.[1] Kingdom Plantae and Dorothy Retallack, it turns out, have the same taste in music.
Her research never appeared in a peer-reviewed science journal, nor has it been replicated. Retallack’s book, The Sound of Music and Plants, was published by DeVorss & Co., a New Age press. The experiments it documents involve such rigorous standards as “The need for water was determined by touching the soil with a finger,” and, “The amount of water was not measured.[2]” She also used a very small sample of plants, leading to a limited data set in a poorly controlled experiment.
While The Sound of Music and Plants is not very convincing science, it is a fascinating look into the mind of a deeply religious social conservative of the late 1960s. Wondering why rock songs killed her plants while they thrived to Indian ragas, even though both forms feature percussion and stringed instruments, Retallack speculates that it’s the “intent” in the music that makes the difference. Ragas involve “praise to the Creator,” while rock music will more typically be heard “referring to the positive effects of drug use, bodily eroticism, and the drop-out culture.”[3] She wonders if perhaps Jesus Christ Superstar, a rock opera based on the Gospels, could be good for plants.[4] Her anthropomorphizing even extends to assuming plants can be bored to death. Discussing some that withered in the presence of white noise, Retallack writes, “I feel they just couldn’t stand the monotony of the constant hum and the ‘meaninglessness’ of the white sound.”[5]
Despite these shortcomings, her results reverberated in the popular imagination, spawning the release of numerous classical records for plants, including the 1975 compilation Music for Your Plants, featuring Vivaldi, Beethoven, and other composers, as well as Music to Grow Plants: Presented by Dr. George Milstein, Allen Seale’s Music to Grow Plants By, and many, many more.
The human tendency to anthropomorphize extends far beyond just assuming plants like Beethoven. We declare lions the king of the jungle, even though we’ve never seen them levy taxes or partition land. As Murray Bookchin writes, “Ecology knows no ‘king of beasts’ and no ‘lowly creatures’ (such terms come from our own hierarchical mentality).” We assess the natural world from within our obscenely stratified systems, and perceive other species as locked in cut-throat battles for resources, just like us. We rarely see anything for what it is. To quote Bookchin again, “If they cannot make human beings into nonhuman animals, they make nonhuman animals into human beings.”[6] Lions are kings. Plants hate Hendrix. Some people get treated like dogs. Everyone and everything gets exploited for profit, dehumanized, and destroyed—but we sometimes have to humanize it first.
Anthropomorphizing plants is part of our problematic penchant for making the natural world a reflection of our societies. So until we create ecological institutions that value diversity and difference along non-hierarchical lines, we will inevitably make the natural world a mirror of our mistakes. It would be much better to study how plants, as plants, utilize sound.
II. When Plants Sing
The Australian biologist Monica Gagliano has done extensive research on plant bioacoustics.[7] Through her work, I learned that in the presence of tones between 200 and 300 Hz, young corn roots generate clicks and pops within that same range. With two corn seedlings in a glass jar—both 14 days old and 8 cm high—plus a small speaker playing a constant sine wave, piezo contact microphone buried in the soil, preamp, and recording device, I was able to document the sound of corn responding to sound. For the first recording, I played the plants a 220 Hz sine wave, and did a second session the following day with 216 Hz. With headphones on, sitting still, trying not to create any vibrations that would make it to the microphone or change the outcome, I felt like I was at a séance—listening for knocks to emerge from the ether. They emerged, and were a haunting but pleasant surprise every time.
What was the corn saying? I’m not sure. Were they communicating? Quite possibly. Plants communicate. Many of the mechanisms are still unknown, but the occurrence of communication is clear. Mast fruiting trees—trees producing acorns and other nuts—make and drop seeds at irregular intervals, anywhere from two to twelve years. Considering the energy it takes to produce such fruits, it makes sense to only do so when there is ample energy. But rather than each individual tree fruiting when it has stored enough starch, they all do it at once. Not just all the trees in a grove, or even in a forest, but across miles and state lines. By fruiting simultaneously, there are guaranteed to be more seeds on the ground than all the squirrels could ever eat, ensuring that the next generation of trees will take root.
In addition, the Canadian ecologist Suzanne Simard has shown that some trees request and share nutrients with each other.[8] This even occurs between species. Simard found Douglas fir and paper birch passing nutrients back and forth through the soil, providing more to whichever was in greatest need. Plants are much more active, communicative, and collaborative agents in the world than people often assume.
Sound could be very effective for synchronizing such swarm behaviors and nutrient exchanges. But humans hear by collecting airborne vibrations with eardrums. Plants have nothing of the sort. So how would plants hear? It is important to remember that many auditory animals, like birds and frogs, lack outer ears, but have much more acute hearing than humans. Snakes detect soil vibrations, and effectively hunt prey and evade predators, despite the absence of both outer ears and eardrums. In fact, soil is such an effective substrate for sound that it would be surprising not to find plants adapted to sensing or sending sound through it.
III. Why Does the Corn Sing?
Since I recorded corn making sounds, it seems fitting to discuss how that particular plant developed and why it might be making those noises. The likely wild ancestor of corn is teosinte. The human selection and transformation of teosinte into corn began about 10,000 years ago in present day Mexico. Despite being members of the same biological species and capable of producing offspring, corn and teosinte are quite distinct. Teosinte grows wild. Corn is only known in cultivation. Teosinte produces many branches and ears, while corn usually makes just one or two.
Humans have regularly grown corn as one of the “three sisters”—corn, beans, and squash sown together. Corn sprouts quickly and establishes itself before the others emerge. Beans appear next, and the corn provides a natural trellis for their tendrils to grab. Because beans have a symbiotic relationship with nitrogen-fixing bacteria, they gather nitrogen for all the sisters to use. Squash is the last to surface. With its broad, low-lying leaves, squash shades the soil in the hot summer months, reducing evaporation and keeping all the plants well-hydrated.
There are other ecologically wise ways to cultivate corn. Iowa-based biologist Lisa Schulte is a proponent of “prairie strips”—wide rows of perennial grasslands interspersed within corn and soybean fields. Such strips can reduce runoff by 40%, quadruple soil phosphorus content, and more than double insect and bird taxa.[9]
But usually, if there are perennial grasses near croplands in the United States, they are monocultures of nonnative species along roads and waterways. Corn is usually grown alone, without a sibling or prairie strip in sight. Given acres of just one species, parasites can boom beyond any natural possibility. So corn is drenched in pesticides. This kills the pests, but also the microbes, fungi, and insects necessary for healthy ecosystems. With no symbionts left to help corn grow, we apply synthetic fertilizers, and the corn limps along on the agricultural equivalent of life support, all alone in a desert that humans created for them.
We grow food by the dictates of the market, not human health or the health of the planet. Fields are planted, ruined, and abandoned. As many as 12 million hectares of croplands become unusable every year, and the long-term survival of complex life becomes increasingly unlikely.
There is speculation that corn’s subterranean clicks mimic the mating calls of certain burrowing insects. Seeking sex, the insects approach the roots and aerate the soil. But we usually kill every insect where corn grows, making these plants pointlessly produce sounds, clicking into a lonely void.
We crafted corn from teosinte. We know how to grow it in sustainable ways. So what will it be? Will corn sing through the soil to symbiotic species? Or will corn sing Earth’s last rites? We are making our choice, and we are making the wrong one.
[1] See, Dorothy Retallack, The Sound of Music and Plants (Marina del Rey, CA: DeVORSS & Co., 1973).
[2] Ibid., 84.
[3] Ibid., 26.
[4] Ibid., 73-4.
[5] Ibid., 24.
[6] Murray Bookchin, Re-enchanting Humanity (New York: Cassell, 1995), 102.
[7] See, Monica Gagliano, et al, “Towards understanding plant bioacoustics,” Trends In Plant Science (2012): 17, 323-
[8] See, Suzanne Simard, How Trees Talk To Each Other (video), June 2016, https://www.ted.com/talks/suzanne_simard_how_trees_talk_to_each_other.
[9] Lisa Schulte, et al, “Prairie strips improve biodiversity and the delivery of multiple ecosystem services from corn–soybean croplands,” Proceedings of the National Academy of Sciences of the United States of America 114, no. 50, 11247.