Police recovered a hidden cannabis growing factory below a rented cottage in the Welsh countryside.
The double garage doors were completely blocked off from the inside.
A court heard how the only access to the garage was via a hidden trap door.
That was in the floor of a cupboard in a bedroom which led to steps down to the garage underneath the cottage.
There, a total of 50 cannabis plants were growing in a sophisticated hydroponics system.
The man who rented the cottage at the village of Llanbedr Dyffryn Clwyd near Ruthin has been jailed for 20 months.
Mold Crown Court was told Dominic Smith , who turned to cannabis because of the pain he suffered following a works accident, had done it twice before, all in rented properties.
Smith, 42, now of Aintree Avenue in Doncaster, South Yorkshire, who was paying £1,000 a month rent for the cottage, admitted producing cannabis and possessing dried flowering cannabis heads with intent to supply, together with abstracting electricity.
Damage to the value of £10,000 had been caused to the property by the illegal enterprise.
Judge Niclas Parry said in 2013 Smith was growing 160 cannabis plants in a rented property and the following year he grew 44 plants – and had received a 12 month prison term at Sheffield Crown Court.
It was clear he had led a criminal life-style because he had committed 60 offences over three decades.
He was then found to have been responsible for creating a “significant, sophisticated cannabis growing enterprise” at Llanbedr DC.
There were four separate growing zones and the potential for profit was significant.
It was not the first grow, but an ongoing process.
The flowering heads had a value of some £8,000 and while the potential yield of the plants was put at anything between £14,000 and £42,000, the judge said that in fairness he would be dealt with on the basis of the lower figure.
But the level of potential profit was great and he had effectively stolen about £3,000 worth of electricity by by-passing the meter.
Judge Parry said the pre-sentence report showed how he had since transformed his life for the benefit of his family.
He had given up drugs and he had significant caring responsibilities.
“But you will understand this has to be an immediate custodial sentence,” the judge told him.
Barrister Karl Scholz, prosecuting, said at 8.15am on August 31 last year police with a drugs warrant searched the cottage.
Asked if there were any drugs in the property, he said there was and led police to the main bedroom where he revealed a hidden trap door in the floor of a cupboard.
That led to a double garage beneath the main house where the small of cannabis was “overwhelming”.
The entire garage and workshop to the rear were being used to cultivate cannabis in four separate growing areas, each with its own lighting and watering system.
He said the double garage doors had been blocked off completely from the inside by a reflective polystyrene substance and an air filtration system set up via an exterior wall into an adjacent open fronted shed in the front garden.
A net carousel was found hanging from the roof which contained herbal cannabis.
Interviewed, he claimed it was all for his own use and said he was in pain following an injury to his pelvis in a works accident.
But Mr Scholz said a drugs expert had described a claim that he was smoking two ounces a day as “ridiculous”.
Barrister Simon Killeen, defending, said since his arrest Smith had made extraordinary changes to his life.
He had left drugs behind and was now a stay at home father so his partner could run a small business.
Smith had been of great support to his two children, one of whom was autistic, and Mr Killeen asked the court to consider suspending the inevitable prison sentence.