New research suggests that some plants communicate via their roots by generating vibrational frequencies (clicking noises) stimulating the roots to bend towards the sound.
It may seem like an avatar world for plants to communicated by sound, but there are many examples existing in nature - "vibrations cause sensitive plants to fold their leaves, and flowers like blueberries and tomatoes only release pollen at the ultrasound frequency of a bee’s wing flap."
It is also suggested that communication by sound is much simpler and resource-effective for plants as opposed to chemical secretion.
Don't underestimate what goes on in your garden, plants are extremely sophisticated.
Via Nikki Kapp, Marybeth Shea