Nga White, also known as Emily White, on Monday pleaded not guilty to directing a criminal group, cultivating a large commercial quantity of cannabis and supplying a commercial quantity of cannabis and faced the first day of a judge-alone trial in Newcastle District Court.

During his opening address, Crown prosecutor Brendan Queenan told Acting Judge Stephen Walmsley, SC, that in early 2017 police discovered a number of bags of cannabis stems and root balls at dump sites around Newcastle.

And because of documents found with the bags of discarded cannabis cut-offs, police were able to identify a number of people, including Ms White, and a number of premises and launch an investigation into the cultivation and supply of cannabis, Mr Queenan said.

After conducting surveillance, police stopped a car at Adamstown in October, 2017, found 18 kilograms of cannabis in the boot and arrested Hoai Nam Nguyen, The Anh Hoang and Cuong Van Nguyen.

The three men, Vietnamese nationals and cannabis crop sitters, were each jailed in 2019 for a maximum of four years.

Using a set of keys found on the men, police were able to gain access to a commercial premises in Steel Street where they located 329 cannabis plants being grown hydroponically and 39 bags containing more than 17 kilograms of cannabis.

Ms White was arrested at a business at Kotara the same day.

Police also searched a number of other premises at New Lambton, Maryland and Mayfield allegedly owned by Ms White where Mr Queenan said they uncovered equipment used for the hydroponic cultivation of cannabis.

During his address, Mr Queenan said much of the details about what was discovered by police at the houses was not expected to be in dispute, with the trial instead expected to focus on Ms White's alleged knowledge or control of the sophisticated operation.

One of Ms White's alleged customers, who cannot be identified, gave evidence on Monday and was played an intercepted phone call between the pair.

The man admitted that during 2017 he had purchased "a couple of pounds" of cannabis off Ms White "probably half a dozen times".

After being played the call, the man agreed that he was trying to buy $50,000 worth of cannabis from Ms White.

The trial, which was expected to feature up to 40 witnesses and run for four weeks, has been significantly reduced due to agreements between the parties.