The police have issued a helpful guide to identify cannabis operations, in the hope growers will be grassed on by the public.

Cannabis growing season is "well underway" and Detective Sergeant Regan Boucher of Southern District police said people should be on the lookout for cannabis growing operations as they travel around this summer.

People carrying shovels, spades and similar equipment into the bush may be up to no good, as may people repeatedly visiting places at unusual times.

Unusual sightings of lights, head torches, and headlights in rural areas at night may be people growing marijuana.

Theft of fencing equipment or farm bikes from rural properties which could be used in accessing plots and cultivation was another sign to look out for, Boucher said.

And where there's smoke, there's likely to be fire - a "distinctive smell" coming from rural areas or properties is another obvious sign.

Police are also interested in cannabis grown indoors.

Constantly closed curtains and blacked-out windows, with bright lights on constantly or at strange times may indicate an illegal indoor gardening operation.

Boucher said cannabis destroyed lives and relationships, and caused millions of dollars of social harm each year when users committed crimes to fund their habits.

Southern police were committed to working with the community to disrupt the supply chain and reduce the demand for cannabis, he said.

Anyone who came across a cannabis growing operation was urged to stay clear, but note its location and report it to police.