Dr. Doofenshmirtz originally used Planty to fill the void when Perry wasn't showing up for his mission. He simply placed a newspaper hat on the top leaf of a nearby potted plant and pretended it was his nemesis, trapping him just like he traps Agent P. The potted plant was then named "Planty the Potted Plant" by Heinz. However, when Planty seemingly started to fight back after he was swung as a pendulum by the very trap he was caught in, Dr. Doofenshmirtz was defeated once more.
Planty was awarded a medal by Major Monogram for its actions in defeating Dr. Doofenshmirtz. This occurred, as Major Monogram phrased it, during one of their "darkest hours" ("No More Bunny Business").
Planty was briefly stationed at the Flynn-Fletcher house, but after a fedora dropped on him, his cover was blown and Major Monogram told him he would have to be relocated with another family. ("Just Our Luck")
Unlike the other agents, Major Monogram refers to him by his full name, possibly to avoid confusion with Agent P (Perry the Platypus).
Planty made a cameo in O.W.C.A. Files. When Monogram was telling Agent P to find and stop Professor Parenthesis, the cart he was on that Carl was pushing crashed and toppled over, and Planty flew across the screen momentarily, still wearing his fedora.