There’s a pungent smell

You may be able to smell the drug’s familiar odour

High levels of condensation on the windows, even in the warmer months. 

The condensation may well be due to the inside having been turned into a makeshift greenhouse.

Constantly covered or blacked-out windows

It might make it look like the house is unoccupied, but blacked out windows could well mean inside is really bright and contains lighting equipment.

A high number of deliveries or large items being taken in or out

Thousands of pounds worth of equipment is often needed for large-scale grows.

A constant buzz of ventilation 

If you can hear the constant noise of a fan, at all times of the day or night, chances are it could be acting as ventilation for the cannabis grow.

Strong, constant lighting day and night 

Cannabis needs light to grow, so watch out for homes with bright lighting at all times of the day and night. Lights will often be on a timer switch, coming on in the middle of the night.

Lots of power cables 

The lights, dehumidifiers and heaters take a lot of electricity. Growers will often hack into the electricity wires before the meter to that individual house, and so bypass having to pay for the electricity.

Lack of snow on the roof 

Cannabis factories produce a lot of heat, which can cause tell-tales signs, especially in winter. When it snows, the roofs of cannabis farms can be obvious as the snow melts, meaning it is probably the only house on the street without a snow-covered roof.

Unsociable comings and goings