More than 700 cannabis plants were found after Tameside police officers raided a site in Droylsden.
Approximately half a million pounds worth of the drug was recovered in an abandoned building on the farm land.
Officers hit the property on Tuesday morning (30 March) as part of an operation into the supply of drugs in Tameside and the UK.
Police believe the site is linked to an organised crime group involved in large scale drug and people trafficking across the country.
They say the investigation comes after receiving concerns from the community and intelligence.
Four men were arrested at the scene and taken to custody on suspicion of the production of cannabis. They remain there for questioning.
Enquiries are ongoing and officers are encouraging anyone with concerns or information about drug supply and criminal exploitation to contact police in confidence.
Superintendent Paul Walker, of GMP's Tameside district, said: "This operation was all about making a significant dent in the supply of controlled drugs, not just in Tameside and Greater Manchester, but across the UK.
"We know there have been community concerns about this particular location and it was important that we took the action we did this morning to disrupt the activity that we believe to have been taking place at this site.
"The intelligence received about the serious criminality those believed to occupying the site were capable of required us to act swiftly and efficiently to negate any threat to ourselves and importantly the wider public.
"While we have four men in custody, our officers in the Challenger team continue with their work with this investigation and to continue to tackle organised crime and drug offences in Tameside.”
Details can be passed anonymously to the independent charity Crimestoppers on 0800 555 111.