Tai Le, 21, and Duc Nguyen, 36, originally from Vietnam, but with an address at Church Street in Portadown, both face six charges.
They include being concerned in the supply of a class B controlled drug and cultivating cannabis.
They are also accused of having a class B drug with intent to supply and dishonestly diverting electricity.
Mr Le and Mr Nguyen were arrested and charged after police searched a house in Church Street.
Officers initially believed the cannabis was worth £500,000, however following the completion of searches the figure is now thought to be in the region of £750,000 to £1m.
"A number of plants, cultivation equipment and associated items have been removed for further examination," Det Ch Insp Stephen Wright told the court.
"Officers on patrol in this area noticed a smell of cannabis and their subsequent enquiries led them to this cannabis factory."
Neither Mr Le nor Mr Nguyen applied for bail. They were remanded into custody and are to appear in court again on 14 November via videolink.
Two men have appeared in court over the seizure of cannabis plants worth up to a £1m in Portadown on Wednesday.