Green-fingered cannabis growers are already being dobbed in early this season by concerned members of the public via the Crimestoppers tip-off line.
Police are commending those Northlanders who are taking a less tolerant line on the illegal drug trade, and are urging people to call anonymously and leave information on the phone line that will lead officers to cannabis plots they would otherwise never find.
Last season Northland police destroyed 48,546 cannabis plants by spraying the crop or by ripping out plants by hand.
Favourable weather forecast for this summer could see just as many plants sprouting.
Northland Detective Sergeant John Miller, who runs the annual blitz on cannabis, said as growers made moves to establish crops in the bush, police had already received information they could use.
"We are getting information about suspicious movements. People are getting located in the bush claiming to be hunting but they have no gun or dog and are carrying a backpack," Mr Miller said.
"Now will be the time they are taking in trays of seedlings, potting mix, fencing equipment and netting to set up their plots." He said businesses selling gardening products would also notice an increase in the number of items being used for indoor and outdoor drug crops being bought.
As people realised they could leave information anonymously on the Crimestoppers line, that there was no comeback on them and police were investigating, it meant more people were dobbing in dope growers.
Mr Miller said attention should be given to houses which could be homes to indoor growing operations where growers were cloning plants, growing them to a certain size and then selling them to outdoor operators.
"It's a massive market - about 80 per cent of cannabis grown outdoors starts indoors," he said.
Clones were taken from a "mother plant" ensuring all were female plants which produced the best end product.
Meanwhile, Detective Sergeant Callum McNeill, Auckland's Coordinator of the National Cannabis and Crime Operation, said cannabis crops lead to other crimes such as burglaries, especially in rural areas.
"Criminals growing cannabis have previously trespassed on private land, destroyed farm crops, intimidated people using regional parks, damaged locks on gates and stolen items such as farm bikes and fencing equipment," Mr McNeill said.
Deerstalkers, pig-hunters, trampers, people taking part in outdoor recreation pursuits, and those who work in the rural industry are urged to assist police by keeping an eye out for suspicious behaviour.
"During the past three years the police eradication of outdoor grown cannabis plants throughout New Zealand has equated to $863 million dollars in social harm prevented."
Anyone who can help is asked to call their local police station. Information can also be given anonymously by calling Crimestoppers on 0800 555 111.