Niagara Regional police said a house on Ridge Road in Grimsby had been under investigation for growing marijuana and investigators executed a search warrant at around 6:45 p.m. Wednesday.
Police said an extensive grow op was found in the basement with more than 500 marijuana plants, 3.6 pounds of marijuana and 440 prescription pills.
Two people were arrested and police estimated the street value of the drugs was about $550,000.
David Warrilow, 57, and Lorraine Sauve, 50, have been charged with unlawful production of a controlled substance, possession of a controlled substance and two counts of possession of a controlled substance for the purpose of trafficking.
Police said both Warrilow and Sauve have been released from custody and will appear in court in May to answer to the charges.