OK, I'll be serious. Check out Cleve Backster's work on plant biocommunication and perception.

He used a polygraph machine to test plants response to different stimuli and even postulated that plants could sense emotions. His work has been duplicated with more advanced testing devices and the results are at best inconclusive.

The most common sense view is that talking, singing, etc to your plants is helpful to them because of the carbon dioxide that is delivered thereby. But who knows? Perhaps plants do respond to emotions. It's a pretty difficult theory to prove.