Scottish judges have been given tough new sentencing guidelines in a bid to crack down on cannabis farms.
Many cannabis farmers come from China or Vietnam
Scotland's senior judge said the move was needed to tackle a big increase in the farms, which are often set up by organised gangs in rented homes.
Lord Hamilton, the Lord Justice General, said even low level cannabis "gardeners" should expect to face between four and five years in prison.
Cannabis plants worth £10m have been seized from illegal farms this year.
Higher sentences for the crime - which carries a maximum sentence of 14 years imprisonment - will be reserved for those involved at a more sophisticated level or repeat offenders.
Guilty pleas would see a reduction in the length of the prison sentence imposed.
The guidance came as Lord Hamilton, sitting with Lord Nimmo Smith and Lord Carloway, rejected an appeal by failed Chinese asylum seeker Zhi Pen Lin against a jail sentence of three years and nine months for producing cannabis.
Lord Hamilton said: "The courts must seek to deter individuals from lending their services to such activity - even where offenders are in circumstances where the pressure on them to participate may be heavy.
"The illegal cultivation of cannabis by organised criminals on a substantial commercial scale appears to be a relatively new phenomenon in Scotland."
The appeal judges heard that since a police operation was launched in December 2006 thousands of cannabis plants had been seized with an estimated yield worth more than £10m on the streets.
More than 50 people have been arrested, mainly of Chinese or Vietnamese nationality. Rented houses were often used to produce the drug crop.
Lord Hamilton said there had been "a degree of disparity" in sentences, at least in the High Court, handed down to those involved in a relatively minor way.
Most of those dealt with had been "foot soldiers" in the drug operations, tending crops under cultivation.
He said, as a significant number of other cases were likely to come before the courts, it was appropriate that there should be guidance over sentencing.
Lin, 32, was caught tending a crop of 849 cannabis plants worth £84,900 at a house in South Street, Forfar.
The five-room bungalow had been leased from its owner. When police forced entry in March this year they found the whole house apart from the kitchen was devoted to growing the drug.
The curtains were closed and doors and floors covered with plastic sheeting. Elaborate electrical cabling had been laid to supply heat and light to the plants.
Lin said he had been approached by a man to stay at the house and water some plants.
The court heard he had fled China and paid money to a "snakehead" gang to make the journey to Britain.
The first offender had come to realise that he was involved in a drugs operation at the house in Scotland, but had no other option than to do what was asked of him as he had no other source of income, a roof over his head or food.
Lawyers acting for Lin challenged the sentence imposed on him claiming it was excessive.
But the appeal judges said: "While the sentence imposed might be described as on the severe side, it is not in our view excessive."