Police found more than 750 cannabis plants in a raid on a Thomastown factory last week.
About 20 police stormed the Goodyear Drive property last Wednesday after a tip-off from a member of the public.
Police believe the street value of the plants to be more than $1 million.
During the raid a neighbouring worker alerted police to a woman standing on the factory roof.
The woman, in her 20s, jumped off the seven-metre building and landed awkwardly, injuring a leg and both ankles. She was arrested, treated for minor injuries and taken to the Austin Hospital in a stable condition.
Police think the woman hid in the roof cavity when police stormed the property then used a rope ladder to climb to the roof.
Detective Senior Constable Daniel Chrystie said it was one of the biggest cannabis hauls he had seen, but the factory’s landlords claimed to be unaware of the crop.
“They seemed pretty shocked,” Detective Senior Constable Chrystie said.
He said police believed the tenants had been operating a hydroponic set-up for about three months.
Anyone with any information about the incident is urged to contact Crime Stoppers on 1800 333 000 or submit a confidential crime report at www.crimestoppersvic.com.au
