In November 2013, Kayden John Smith's Ravenswood home was searched by police after they learnt he was selling cannabis on Facebook. The 20-year-old was arrested after a small amount of pot was found.

During the police interview Smith curiously volunteered that he'd been involved in a large operation for four years.

This included selling at least $475 of dope a day and growing a large crop that could yield 16 kilograms of cannabis from one harvest.

He told police that he irrigated the property and used blood and bone fertiliser while leaving his dog there to protect it. 

Smith said he'd buried $60,000 in cash, owned several vehicles and properties and enjoyed overseas holidays.

He was charged with trafficking and while pleading guilty went on to claim that much of what he told police was bunkum. 

During a disputed facts hearing in the Supreme Court in Launceston on Wednesday, Smith said he only began regularly selling cannabis in 2013.

On this version he sold the cannabis for others who  grew the crop.

The vehicles, properties, and buried cash did not exist.  

He was told that he should say he was the person who grew the cannabis if he was caught, which is what he did, he said.

He randomly came up with numbers when describing how much pot was grown. 

Yesterday, Justice Robert Pearce determined the truth was somewhere in the middle.

He found Smith's explanation about being paid $125 for cannabis he'd been supplied for $300 and onsold for $475 made little sense.

``Mathematics cannot be his strong point,'' he said.

As a witness his evidence lacked credibility.

``On neither occasion did he impress me as a person of intellect or initiative,'' Justice Pearce said.

``I am not satisfied he has the wit or wherewithal to grow and sell cannabis on the scale he described to police.

``His presentation is inconsistent with a person with ready access to large amounts of cash.''

Justice Pearce determined Smith played an active roll in the enterprise but did not act alone. 

He found Smith onsold about 7kg of dope over a 245-day period, benefiting to the tune of $40,000.

In his sentencing submissions defence counsel Fabiano Cangelosi said Smith had squandered all of his profit on pot and ice. 

He said Smith had become a cannabis user at a young age, using it to withdraw from a violent household where abuse was directed at him and his mother.

His father also encouraged him to smoke dope, he said. 

Mr Cangelosi said jail was an appropriate sentence but it should be wholly suspended given Smith's age. 

The prosecution, which is seeking a pecuniary penalty order, will make sentencing submissions on June 10. Smith will be sentenced on July 3.