What type of music can affect a plant's growth?

Many scientific studies have been done regarding which music affects plants in which ways, and no definite conclusions have been made.

Many studies have suggested hard rock or heavy metal music seems to have a detrimental effect on plant growth.

There is a well-known study from the early 1970s, conducted by Dorothy Retallack at the Colorado Woman's College in Denver using the college's three Biotronic Control Chambers. Among other experiments, she also tried different types of music and studied their effects on plants. She tried acid rock music by Led Zeppelin, Vanilla Fudge, and Hendrix. It was played to one group of plants and semi-pop music (of the 1970's) to another. The "acid rock music" plants were sickly and small compared to the control group of "semi popular" music (now termed soft rock).

The other genres of music she experimented with: were classical music (Debussy), jazz (she use Louis Armstrong among others), and Indian (Ravi Shankar). The plants grew large and healthy, with the plants actually growing towards the radio for each of these three forms of music, just like they bend towards sunlight. Dorothy also experimented with country music (such as Jonny Cash) and found they neither grew toward or away from the speakers and seemed neutral. Some doubt has been cast over whether her experiments were consistent in the variables, or whether she was biased towards classical music as being the best for plants.

It seems the plants like all types of music, except hard, pounding rhythms, but prefer stringed instruments the most.

On the other hand, Mythbusters did their own experiments and obtained a different result. Their experiments suggested that heavy metal seems to stimulate growth more than other types of music. The catalyst is possibly the rapid vibration that encourages activity.