An illegal immigrant from Vietnam, who worked as the gardener at a Borehamwood cannabis factory, has been jailed for eight months.
Duc Hoang watered and tended to the plants at the house in Alexandra Road, where he was given food and accommodation, but no pay.
The 33-year-old had only been this country for a few weeks when he was arrested on December 7 last year, St Albans crown court was told.
Prosecutor Sally Mealing-McLeod said the police noticed a strong cannabis odour when they went to the property.
Hoang unlocked the door and inside the officers found hydroponics systems in three bedrooms. There was powerful lighting, fans and a watering system.
Officers seized 144 fully grown cannabis plants, along with 120 seedlings.
Hoang pleaded guilty to being concerned in the cultivation of cannabis. He appeared for sentence from Bedford prison yesterday and was aided by an interpreter.
Henry Day, defending, said Hoang had arrived in the UK last November from France.
"His intention was to look for work. He was approached by Asian males, who offered food and accommodation at the address. He had never engaged in paid work here," he said.
Mr Day said Hoang played a lesser role in the operation, watering and tending to the plants. He said he now wanted to return to his family in Vietnam.
Judge Marie Catterson told him: "You played a lesser role, but nonetheless an essential role. It was a professional operation."
She said the Border Agency will take steps to remove him from the country.