1x16 - The Adventures of Superboy

Professor Potter gives Superboy a serum that he believes will protect him from Kryptonite. Unfortunately some of the professor's plant growth formula has gotten into the serum and Superboy grows to enormous proportions. Superboy realizes the problem of being a giant when he becomes a danger to those he is trying to help. Eventually Professor Potter comes up with an antitdote and Superboy is returned to his normal size.