Kelp Grow is a spray that plays a major role in the episode "Giant Squidward."
The bottle is yellow with a light green burst effect and the product's name is written in capital blue letters. The bottle also has a white top.
It is used to revive withered kelp. If it is sprayed on anything else, it'll make it bigger. SpongeBob and Patrick thought that if the bottle is turned upside-down it will shrink things, but they were wrong.
After SpongeBob and Patrick witness Squidward using this spray on his kelp garden, the pair is amused by its ability to increase the size of things, so they decide to test it out on numerous objects like an ice cream cone and Gary's shell. They then decide to use it on Squidward by spraying a majority of it on his body parts, which winds up turning him into a giant and having to give into the Bikini Bottomites' commands to prove that he's nice, much to Squidward's irritation.