800 cannabis plants with an estimated street value of €640,000 have been seized in Rathcormac, Co Cork.
Five men, all Chinese nationals aged in their 20s and 30s, were arrested. They include two gardeners living full-time in the warehouse.
The five are being questioned at garda stations in Fermoy, Midleton and Cobh.
The plants were set around two months ago and would have been ready to harvest within the next four weeks.