Darren Taylor, of Bournebrook Crescent, Halesowen, was at home on December 2 last year when he noticed the three men approach his property on bikes.
The 55-year-old knew the robbers were after his crop of 33 cannabis plants, and though running an illegal operation he still decided to ask the law for help.
Officers responded before Taylor was attacked and, though relieved not to be injured, he had to explain the plants and an electricity extension from the neighbouring property.
Prosecuting, Mr David Tremain told a court: “On the evening of December 2 last year, the police received two emergency calls concerning a break-in at Bournebrook Crescent, Halesowen. One of the calls was from the defendant who said he was in fear for his safety after seeing three men approach his property on bikes. He said they were armed.