How to spot a grow house

There has been plenty of examples where ordinary homes are turned into makeshift cannabis grow houses, so we need your help to shut them down.

Here are some signs to look out for:

Strong, sickly smells

It may sound obvious, but most hydroponic cannabis crops are discovered by passers-by or keen-nosed residents catching a whiff of the drug’s familiar smell. A cannabis crop takes about three months to grow and in the final weeks, the plants can really stink.

Windows are constantly covered

Maybe your neighbours have curtains drawn all day long or have panelling or sheeting up at windows to hide something they don’t want you to see. This could be a sign that there are many budding plants inside soaking up bright artificial light.

Excessive security

Drug growers live in constant fear that their home-grown set-ups will be discovered by police, landlords or rival drug dealers. If there are padlocks on the gates, massive security features and double and triple locks on the doors, that should certainly raise eyebrows – especially if a street is relatively safe. It is also not unusual to spot bars on the windows and CCTV cameras to alert for possible intruders.

High levels of condensation

Are the windows always misted up? From the inside, landlords might notice damp on the walls or peeling wallpaper, while from the outside a neighbour might spot condensation on the windows, even when it’s not particularly cold outside. The condensation may well be due to inside having been turned into a makeshift greenhouse. For the best plant growth, cannabis needs an atmosphere similar to a greenhouse, and this can cause a lot of condensation.

Lots of visitors – especially at odd hours

Frequent and varied visitors to a property, often at unusual times, could mean you just have a popular neighbour with a big family. But if unfamiliar faces are turning up next door day and night, it might be a sign that there’s something more sinister going on. One thing to watch for is lots of new faces coming knocking.

High electricity bills

The lights, dehumidifiers, hydroponic systems and heaters take a lot of electricity. Many hydroponic set-ups have been found where growers illegally bypass the electricity metre so they don’t have to pay for the massive amounts of electricity used. If you are a landlord who happens to get a copy of a bill that has gone up or down suddenly it might be a sign that a neighbour has tapped into your supply and you are inadvertently funding their drug growing operation.

What happens when it is cold or frosty?

Hydroponic cannabis set-ups produce a lot of heat, which can cause tell-tale signs, especially in winter. When it is frosty, a roofs can be an obvious sign because it is too warm for frost to settle.

Bright lights day and night

It’s strange for anyone to need unusually bright lights on 24 hours a day. Cannabis needs light to grow, so be on the lookout 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.

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.

If you have any information – or suspect – that cannabis is being hydroponically grown then call Crime Stoppers on 1800 333 000 or make a report at

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