CANNABIS farms found in the district over recent months have been worth an estimated half-a-million pounds, police have said.
Raids at three sites in Ripon and one in Harrogate in the past 18 months have uncovered vast grows ranging in size from 150 to 750 plants.
Now police are warning residents to be aware of growers who could be using residential homes as a base for their criminal activities.
“We need to be vigilant,” said DC Karen Spivey, drugs liaison officer for North Yorkshire Police.
“It’s an ongoing problem – it’s for us all to do our bit.”
The news comes as the Association of Chief of Police Officers (ACPO) releases its national profile for the cultivation of cannabis.
It says the threat is increasing, with a rise in the number of robberies, burglaries and violence linked to cannabis farms in domestic properties.
Allan Gibson, commander of the Metropolitan Police Service, said: “Commercial cultivation of cannabis continues to pose a significant risk to the UK.
“Increasing numbers of organised crime group are diverting into this area of criminality. Their perception is that it is a low risk, highly profitable criminal business.”
The ACPO report says the UK has seen a massive increase in the number of cannabis grows found in the past five years .
It said there is an increase in small-scale grow sites and that domestic or residential properties are the “favoured location”.
In the past 18 months, North Yorkshire Police have uncovered four farms in Harrogate and Ripon.
A raid at a house on Aismunderby Close in Ripon in 2010 found 500 plants worth an estimated £125,000.
Another in Ripon, in 2011, uncovered a further 500 plants.
A final raid in Ripon, in February last year, uncovered another 150 plants, worth £37,500.
In Harrogate, a raid on a house on Skipton Road in May last year found 750 plants - with a total worth of around £187,000.
DC Spivey said that while the Harrogate district hasn’t seen any significant rise in the number of farms found, it was still important for people to be aware and vigilant.
“There are some things that should be raising red flags,” she said.
“People don’t tend to pay a year’s rent up front in cash payments. There’s no way that should be happening.
“At one property, in Ripon, people said they had seen deliveries of goods late at night.
“I don’t think, in the Harrogate district, it’s any more prevalent than it was three or four years ago. In fact, properties are probably harder to get hold of.
“But if it sounds too good to be true, then it probably is.”