Landlords and letting agents are in the front line of weeding out cannabis farms as criminal gangs increasingly turn rented homes and commercial properties into drug factories.

Police are increasingly calling on landlords to regularly inspect their rental properties to catch the gangs.

Drugs squad police are regular visitors to landlord forum meetings and have teamed up with letting agents to spread the word about how to spot the tell-tale signs of a cannabis farm.

In the past few weeks, cannabis farms were raided in Wigan; Leeds; Hull; Tyneside; Ipswich; Sevenoaks, Kent and Chester.

Police in Stockport, Greater Manchester, have raided almost 40 cannabis farms​ in the past year.

Inspector Neil Cook, from the town’s neighbourhood police team, said: “We have uncovered quite a few cannabis farms.

“The links we have found are to organised crime groups who generally prey on vulnerable people, that it why it is a priority for us.

“The criminals fund their lifestyle through supplying drugs, which they need to produce somewhere and these are the places we target to disrupt their activity and where possible bring them to justice.”

Police say many of the country’s cannabis farms are run by organised gangs from South-East Asia who install a small team of illegal immigrant ‘gardeners’ to pay off their travel costs to the UK by guarding and tending the crop.

The Association of Residential Letting Agents publishes a leaflet for landlords and letting agents on how to spot a cannabis farm as a handy guide – here are some of the tips:

  • When visiting a rental property a giveaway sign of cannabis plants is a strong smell
  • Cannabis is difficult to grow in the open and needs watering and lighting to mature – watch out for professional hydroponics for watering, extra industrial lighting and ventilation to remove the odour of the plants
  • Windows will be blacked out with silver foil or heavy plastic and will probably show signs of condensation
  • Condensation indoors will show as peeling wallpaper and paint and damp patches on floors and windows
  • Most cannabis factories have bypassed electric meters and makeshift wiring
  • Much of a mature plant is thrown out during harvesting, so bins and the garden may be full of stalks, foliage and discarded root balls from pots

Other signs to watch for are tenants paying rent for six months or a year upfront.

“Often the drugs gang has someone local fronting property rental so they pass credit checks,” said the police spokesman.