Cannabis ‘scratch and sniff’ cards are to be sent to thousands of households in a bid to help people spot hidden marijuana farms.
The cards, which release the odour of cannabis when scratched, are being sent out by Crimestoppers as part of a campaign to tackle cannabis cultivation in the UK.
Police say illegal drug farms are a growing crime – there was a 15 per cent increase in cannabis factories in 2011/12.
It is hoped the cards, which produce the exact smell cannabis plants produce when they are growing, will allow citizens to recognise the odour and call the police if they notice it.
The cards are being sent to 13 areas of England where the number of marijuana plantations have traditionally been highest - Avon & Somerset; Greater Manchester; Hertfordshire; Humberside; Kent; London; Merseyside; Northamptonshire; Nottinghamshire; South Yorkshire; Suffolk; West Midlands and West Yorkshire.
West Yorkshire police area had the largest number of cannabis plantations uncovered in the UK.
The initiative started three years ago in Holland, where 30,000 scratch cards were distributed to homes.
A UK 2012 report found residential properties are increasingly being used to grow cannabis plants.
The Association of Chief Police Officers (ACPO) lead for drugs, Andy Bliss, said: “Closing down cannabis farms and arresting the criminals who run and organise them is a key focus in drugs policing.
“This is because we recognise that these farms are often run by organised criminals but also because they bring crime and anti-social behaviour into local communities causing real harm and leaving people feeling unsafe.
“We also know that many people don't realise that the empty, run down house or flat on their street with people coming and going late at night may actually be a commercial cannabis farm. It's not just the stereotype of the remote rural set or disused industrial estate unit.
“The Crimestoppers campaign will help members of the public to recognise the signs and smell of a cannabis farm.
“The police will use the intelligence generated by the campaign to help build on recent successes in tackling this issue.”
Founder and Chairman of Crimestoppers, Lord Ashcroft KCMG PC, said: “Cannabis farms grow more than just drugs. Those who are cultivating cannabis tend to be involved in other areas of crime and are often involved in related gang crime and other violent crimes involving firearms.
“These individuals use violence and intimidation to carry out these crimes and endanger the lives of those around them. We want to help put an end to this and the funding that cultivation provides to serious organised crimes like human trafficking and gun crime.”
Crimestoppers Director of Operations Roger Critchell said: "We are distributing ‘scratch and sniff’ cards because not many people know how to recognise the signs of cannabis cultivation happening in their neighbourhood.
“Many are also not familiar with the established links between this crime and serous organised crime.”
As a class B drug, supplying cannabis in the UK can lead to a 14 year prison sentence.
Aside from the smell, signs a property is housing a cannabis farm include constantly covered or blocked-off windows; unsociable coming and going at all hours and lots of people visiting; strong and constant lighting day and night and high levels of heat and condensation.
There may also be a constant buzz of ventilation and lots of power cables - gangs dig underground to lay cables which hook up to lamp posts so they don’t have to pay for the enormous amounts of electricity they use.
Crimestoppers is asking members of the public to pass on any information about cannabis farms anonymously by telephoning 0800 555 111 or via our anonymous online form via www.crimestoppers-uk.org.
Both routes are anonymous – names are not taken, calls and IP addresses are not traced or recorded and people do not have to go to court.