A lawyer for the man who poisoned nine of his colleagues with a cannabis-spiked Christmas cake has blamed his client's actions on long-term cannabis use.

Photo: Supplied / Ministry of Justice

Graham Jones appeared at the North Shore District Court today where Judge Nevin Dawson jailed him for 22 months.

Jones worked at a car wreckers in Hillcrest and baked a Christmas cake with an unknown amount of cannabis.

Judge Nevin Dawson said the 58-year-old hid the plate of cake under clothing as he came into work and left it in the lunch room. Nine of Jones' workmates ate the cake.

"Shortly after consuming the cake, one of the victims experienced an increased heart rate and shortness of breath and believed he was having a heart attack. An ambulance was called and other employees, who had also eaten the cake, began experiencing similar symptoms."

Eventually three ambulances and an advanced paramedic were called and the victims were taken to hospital.

Later that day the police searched Jones' home and found a cannabis growing shed and three firearms.

Jones' lawyer Robin Brown blamed his client's drug use.

"This very sad affair was a result of long-term usage of cannabis which somehow has effected his judgement, caused him to make the bad decision he made and not only effected people in the workplace, but his friends that work there."

Mr Brown continued: "People who undergo long-term usage of cannabis do things, which in the cold light of day, they regret and wouldn't do otherwise."

He said his client had undergone surgery for saliva cancer. The court heard how he had had his tongue and some of his teeth removed.

"There were times, Sir, when he couldn't get to sleep, the pain was that bad. Not even sleeping tablets would alleviate the pain that he was suffering. He did, however, receive relief, strange as it might sound, from cannabis."

Mr Brown said the cannabis was for Jones' personal use.

In sentencing, Judge Dawson said Jones' behaviour was extremely foolish.

"I also need to take into account the effect of your offending on all nine victims. They were extremely distressed and, of course, they had no idea what was happening to them. They knew something was wrong."

Judge Dawson said Jones' offending was very dangerous.

"Your offending had a very high potential for harm because it happened in a workplace that uses heavy machinery and equipment. An accident there could very easily have led to an accident or deaths of workers."

The judge noted Jones had over 40 previous convictions, including three for violence.

He took time off Jones' sentence for his remorse and early guilty plea.

Jones had applied for home detention but his home at Kaukapakapa was so remote that authorities couldn't get a signal.

Judge Dawson allowed Jones to apply to substitute his jail sentence for home detention if he could get an address.

Jones' daughter wiped tears from her eyes as her father was led into custody.