Over 1000 cannabis plants, methamphetamine, 8kg of ready-for-sale marijuana and $800,000 cash have been seized by police in Feilding.
Police found two large sheds at a Feilding home while responding to a firearms incident last week.
"This is one of the most significant indoor cannabis operations discovered in the past 10 years," said Acting Detective Senior Sergeant Dave Thompson.
"This operation has been a major and consistent source of cannabis for both the local and Auckland markets for a number of years."
A 44-year-old man and a 46-year-old woman, both from Feilding have been charged with cultivation of cannabis.
They have been remanded on bail and will reappear in the Palmerston North District Court later in January.