Around 1,000 plants with a street value of about £700,000 were found inside the property.
It is the largest cannabis factory ever to be found by Hertfordshire Police.
The was discovered last Tuesday (October 17) in Hatfield Road, Potters Bar, after police received an anonymous call by a member of the public just days after a plantation was discoverd in woodland area.
A 23 year old man from Barnet was arrested on suspicion of cultivating cannabis, abstracting electricity and criminal damage. He has been released under investigation while enquiries continue.
It has now been dismantled and destroyed by police officers.
Hertsmere Chief Inspector Steve O’Keeffe said: “My team responded to an anonymous call from a concerned member of the public which prompted a quick and covert response.
“The scale of this factory is believed to be the largest ever uncovered in Hertfordshire, with the plants estimated to have a street value of £700,000.
“The cultivation of cannabis can put surrounding residents at risk as unlawful electrical wiring used to power the systems to grow the crops creates a fire hazard.
“This case demonstrates the key part members of the public play in reporting anything suspicious in their local area so that officers can act on intelligence and take action to disrupt the supply of drugs across the county.