A total of 7,865 farms were found across the UK in 2011/12 - up 15% from 6,866 in 2009/10 and more than a 150% increase on the figure four years ago.
In the two years since the last report by the Association of Chief Police Officers (Acpo), some 1.1 million plants with a street value of £207.4m have been discovered.
The number of offences related to cannabis production is also increasing, up from 14,982 in 2010/11 to 16,464 last year.
Police chiefs say the size and scale of cannabis-growing operations are reducing as criminals spread the risk and use so-called "gardeners" to manage small sites in residential areas.
Scotland Yard Commander Allan Gibson, the lead on cannabis cultivation for the police chiefs, said: "Commercial cannabis cultivation continues to pose a significant risk to the UK.
"Increasing numbers of organised crime groups are diverting into this area of criminality but we are determined to continue to disrupt such networks and reduce the harm caused by drugs.
"This profile provides a detailed analysis of the current threat from commercial cultivation of cannabis and the work undertaken by law enforcement agencies to combat the threat."
The highest number of farms - 936 - were found in the West Yorkshire force area, with the equivalent of 42 factories per 100,000 people, according to the Acpo figures.
South Yorkshire had 851 farms but there were 64 per 100,000 people, giving it the highest ratio in the UK.
The West Midlands had 663 farms, the Metropolitan Police 608 farms and Avon and Somerset 653 farms.
Devon and Cornwall saw the highest rise since the last report, up a massive 1,664% from 11 in 2009/10 to 183 in 2011/12.