Milne, 68, was acquitted of an earlier charge of growing cannabis, and another of selling the drug, between 2013 and 2016.
Co-accused Anthony Wayne Harris, 77, of Ngahere, was found not guilty of one charge of selling cannabis leading up to 2016, but guilty of two counts of selling the drug between 2016 and 2019.
The Crown submitted telecommunications polling data that showed Harris had travelled almost weekly to Christchurch.
Prosecutors said that was to transport the drugs to the city, whereas his defence lawyer argued it was to take his dog to the vet, visit family, and a former girlfriend.
Harris was also found guilty of unlawful possession of various restricted weapons including a taser and pepper spray, as well as ammunition that was found at his house and in his vehicle.
The Crown said the ‘‘arsenal of weapons’’ was indicative of the ‘‘criminal underworld’’ the pair were operating in.
Judge Paul Keller said yesterday the scale of offending was ‘‘significant’’ and warned both Milne and Harris to prepare for a sentence of imprisonment.
A sentencing date is yet to be set.
However, both have been granted bail in the interim.
Milne’s lawyer Helen Coutts said Milne had about 30 guests booked at Cowboy Paradise for Easter Weekend.
He was ‘‘on his own’’ at the site, where he did all the cooking. He was unable to get staff and he also had deer to take care of on the farm.
Opposing bail, Crown prosecutor Cameron Stuart said Milne and Harris had known this day was coming for four and a-half years.
They were arrested in September 2019 following a police raid of their properties following a two-month covert operation.
Access to the underground hydroponic set up, filmed on secret police cameras, was through a trap door in a 40ft shipping container and down a ladder.
The jury heard the bunker had the capacity to grow about 816 plants or 136kg of cannabis bud head a year, netting $1million annually.
The Crown alleged the bunker could have been built as early as 2008 when Milne, formerly of Christchurch, started to build the Cowboy Paradise venture, which includes a pistol range, saloon and accommodation units.
Prosecutor Cameron Stuart said Harris started to accumulate ‘‘significant’’ amounts of cash deposits in 2012. Intercepted phone calls revealed not only how they organised an exchange of cannabis that Harris would carry regularly to Christchurch, but knowledge of a shared venture and investment, which was highlighted in a ‘‘panic’’ call to Milne after Harris’ property was searched.
Harris told Milne to clear out the bunker, and to get a new cellphone.
‘‘There was a big clean-up. No cash at the premises. All the other evidence was gone as well,’’ Mr Stuart said.
However, lawyers for Milne and Harris argued the Crown’s evidence pre-2017 was ‘‘circumstantial’’.
Judge Keller yesterday estimated a starting point for both of at least three years in prison.
The ‘‘sheer scale’’ of the cultivation was significant.
‘‘It’s one of the most significant cultivations I’ve ever encountered.’’
The time it took to get to trial was also noted.
‘‘I think it’s fair to say you’ve dragged this out for as long as conceivably possible, which will be a factor in sentencing.’’
As part of their bail conditions, neither man is allowed to travel east of Otira.
