The fire was reported around 2 a.m. in the 6400 block of Menlo Drive, off of Almaden Expressway.
Crews arrived in about four minutes and saw light smoke coming from the garage, San Jose fire Capt. Mary Gutierrez said. They extinguished the fire, and no injuries were reported.
Police Sgt. Jason Dwyer said marijuana was found in the garage but declined to provide more details. He said police are investigating whether the marijuana grow was legal.
The blaze was contained to the garage, and no residents were displaced, Gutierrez said.