Petunia Blankenhooper is Charlie, Teddy, Toby, Gabe, and PJ's grandmother. She is Amy's mother, Hank's wife, and Bob's mother-in-law. She did mention that she does not have a computer, does not know how to work a VCR and doesn't have a DVD player. She calls and talks to Teddy and Charlie, while Gabe doesn't want to. Gabe refuses to because of it not being Christmas or his birthday and Amy just leaves saying that she isn't in the room ("Bye Bye Video Diary"). She also strongly dislikes Bob and constantly blames him for all of Charlie's rebellious behavior.
She must have had learned how to use the internet (in the end) because she has a Buddy Page ("Alley Oops").
Charlie Goes Viral (mentioned only)
Bye Bye Video Diary (mentioned only)
Alley Oops (mentioned only)
Can You Keep a Secret? (mentioned only)
Good Luck Charlie, It's Christmas! (first appearance)