Born in Los Angeles, California, he was a rebellious boy whose teachers believed he would never get anywhere in life. He earned his master's degree from UCLA. He was an engineer before working on his first and best-known children's book, Stone Fox, which, at the time of his death in 2006, had sold four million copies. Always creative, in his younger years he ran Num Num Novelties, home to such originals as the aquarium tie. He lived in West Germany and Central America, and taught writing workshops around the world. Gardiner also edited children's stories for television. He lived out his final years with his wife, Gloria, in California and died of complications from pancreatitis in Anaheim, California.