Do plants grow better if you talk to them?
Last evening, after perusing The Straight Dope: A Compendium of Human Knowledge over a leisurely dinner of canned soup, I spent several hours nursing my apartment full of sick plants. My inquisitive capacities had been piqued by your book, and naturally I fell to wondering: is it true what mom used to tell me, that plants enjoy being talked to? My mother taught me all I know about plant care, and I follow all her instructions to the letter (except the talking bit, which I always thought was crazy), yet her plants are infinitely healthier than mine. Is there any scientific evidence that plants respond to the human voice or presence? Do some people (like mom) give off "vibes" that plants really like while other peoples' "auras" (my own, for instance) leave them cold? Might this have anything to do with the fact, known the world over, that babies always cry when held by certain people or that cats are passionately attracted to people who are deathly allergic to them? Help, Cecil.
Cecil has heard this "vibes" stuff for years, Gato, and with all due respect to your mother, he regards it as mush-brained bunk. I have never come across any serious study suggesting that your phlox will flourish if you whisper in their little ears, or whatever it is phlox have got. On the other hand, there's a fair amount of research indicating that sound in general (i.e., vibes in the literal sense) can stimulate growth. Admittedly, a lot of this research has been conducted by high school students in New Jersey and whatnot, but hey, we gotta be open-minded about this. Some years ago, for starters, little Evalyn Horowitz won a prize for her science fair project showing that radish seedlings exposed to ultrasonic vibrations of 50,000 cycles per second for a month grew 89% taller than a control group. Curiously, the tall radishes were much spindlier than their untreated cousins, which were stubby but sturdy. Evalyn hypothesized that the ultrasonic sound acted somehow on auxins, which are plant hormones that encourage elongated growth.
Other types of sound are also credited with encouraging plant growth. University of Ottawa biologist Pearl Weinberger found that wheat seedlings exposed to 5,000 CPS sound (within the range of human hearing) weighed 250 to 300 percent more than untreated controls, and had four times as many potentially grain-bearing shoots. Music, too, will do the job, although it's not clear what type is best. In 1970, Mrs. Dorothy Retallack, then a 48-year-old housewife-turned-college-student (like I say, the researchers in this field aren't exactly on the cutting edge) attempted to demonstrate that "soft, semi-classical music" — e.g., Mantovani, or one of those cornball "Music to Grow Plants By" records — would cause plants to thrive, whereas hard-core rock and roll would make them wither and die. (She also believed that there was "a link between loud rock and anti-social behavior among college students," which gives you an idea of Mrs. Retallack's level of social insight.)
More recent work by four University of North Carolina scientists casts doubt on Mrs. Retallack's hypothesis. Their research indicates that 100 to 110 decibel noise (the equivalent of standing 100 feet from a 727 jet) will cause 100 percent more turnip seeds to germinate in 10 percent less time than with a control group. This suggests, of course, that a healthy jolt of industrial-strength heavy metal may be just the thing to invigorate your rutabagas. Give it a shot and let Uncle Cecil know what happens. If you'd rather build your own ultrasonic sound generator instead, there's a diagram in the May/June 1984 Mother Earth News.
A parting shot
Cecil's assistant little Ed was on the old Pat Sajak show when this question came up. In one of his rare flashes of wit, little Ed said, "Well, some people say plants will thrive if they hear dentist's office music, but they'll die if they hear rock 'n' roll. Which to me says that plants may have feelings, but they don't have any taste." The audience was destroyed.