Four people are being questioned by police after £150,000 worth of cannabis plants were seized in Castlewellan.
Two men, both aged 33, and a 22-year-old woman were detained in the Circular Road area on Tuesday.
A 30-year-old man was arrested in Corrywood Park.
All four remain in police custody.
DCI Ian Wilson said: “Officers carrying out proactive drugs searches at properties in the Circular Road and Corrywood Park areas yesterday uncovered two substantial cannabis factories.
“Operations such as this one demonstrate our ongoing commitment to working with communities to tackle drugs, disrupt criminals and keep communities safe.
“We are extremely pleased to have shut down these cannabis factories and prevent the drugs they produce from circulating on our streets.
“Drugs destroy lives and I would continue to encourage anyone with any information about the sale and supply of illegal drugs in the community to contact police on 101 or ring the Crimestoppers charity anonymously on 0800 555 111.”