Detectives have seized drugs with an estimated street value of 400,000 euro.
A man and a woman arrested during the operation in Lucan, west Dublin, are being questioned about the cannabis find.
The haul was uncovered in a raid on a house in the Hillcrest Heights area. The cannabis herb has been sent for forensic analysis.
A man in his late 20s and a woman in her early 20s were arrested at the scene.
They are being detained at Ronanstown and Lucan Garda Stations under the Drug Trafficking Act. The arrests were made as part of an ongoing investigation into the sale and supply of controlled drugs in Dublin.
The operation was carried out by the Lucan Drugs Unit and Garda National Drugs Unit. A Garda spokesman said: "Investigations are ongoing."
In a separate seizure, gardai uncovered another grow house in the west of the city.
A large number of cannabis plants, with an estimated value of about 80,000 euro, were found in a house in Tyrconnell Road in Inchicore.
The home had been converted into an elaborate grow house with lighting and cultivation equipment.
The raid took place after emergency services attended a fire at adjoining property at about 1.50am. No arrests were made.