Penny: You don't have to worry, unlike Amy and Priya, I know how to keep a secret.
Leonard: You're the one who told Amy in the first place.
Penny: In confidence!

Amy: Did I tell you our lab got a grant to study addiction?
Sheldon: No.
Amy: Fascinating work. I recently trained a Capuchin monkey to smoke cigarettes.
Sheldon: Have you learned anything?
Amy: Yes, he looks much cooler than the non-smoking monkeys. Although it's not much of a contest, the other monkeys just sit around and masturbate.

visual: Amy knocks on Penny's door.
Penny: Oh, hey Amy, what's up?
Amy: Sheldon and I engaged in sexual intercourse, in other news, I'm thinking of starting an herb garden, mum's the word, gotta go!
visual: Penny stares after Amy with a stunned expression.

The title of this episode alludes to Sheldon and Amy's experimentation on their friends. By dropping two independent seeds of information, they wait to see how fast each seed will spread, or germinate. The experiment is designed to confirm their intellectual superiority by demonstrating their friends' love of gossip.