Several experiments have been done to see how plants react to music, and often it is classical music that seems to yield the most positive results.
In 1973, Dorothy Retallack published a book titled, "The Sound of Music and Plants." In her experiments, Retallack subjected different groups of plants to various types of music and sounds. In her experiments, she found that soothing music resulted in healthier plants and better growth, whereas music that was more lively and percussive in nature turned the plants away from the speakers. For instance, orchestral renditions of rock songs caused the plants to move toward the speakers but the original recordings of the same songs caused the plants to move away. In another experiment, classical Northern Indian music, featuring sitars and tabla, and Bach organ music were played and, while the plants liked both types of music, they seemed to prefer the Indian music. In yet another experiment, she found that modern, dissonant classical music was preferred over rock music, though the plants reacted negatively to both.
Taking a note from Retallack's experiments, Don Robertson—composer, author, and founder for DoveSong.com—performed his own experiment, playing modern classical by Arnold Schoenberg for one group of plants and music by Giovanni Pierluigi da Palestrina, a late 16th century Roman Catholic composer, for another. Plants subjected to the music of Palestrina, which was more soothing, thrived while the plants subjected to Schoenberg died.
More scientific studies have been made to examine the effects of classical music on the genetic level. In these studies, it was found that low frequency sounds can activate enzymes, increase cell membrane fluidity, and promote DNA replication. Frequencies between 125Hz and 250Hz stimulate certain genes that help to give a plant's DNA instructions for biological processes, such as growth. Frequencies made at 50Hz actually made those same genes less active.
In a study done at a the Tuscan winery Il Paradiso di Frassina, shoot growth and total leaf area per vine were always higher on vines that were subjected to classical music as opposed to no music at all. In addition, volume doesn't seem to be as much of a factor when it comes to plants. Low volumes of music are adequate to achieve results.