"I have no doubt that is one of the main reasons we have seen a rise this year, particularly in respect of the indoor grows where offenders are under the misapprehension that they can hide from us."
The higher numbers were also partly due to a good growing season caused by damp weather, Mr Borrell said.
Plot sizes ranged from five to 150 plants and police found a range of growing methods from sporadic, random planting to plots fully enclosed by netting.
"Sheds, spare bedrooms and even an underground bunker have been used for indoor crops," he said.
Yesterday, eastern region police announced they had seized close to $1 million worth of cannabis from a Gisborne property during a drug-busting operation across that region.
A sophisticated growing room set up in a hay barn on the property was thwarted and 430 mature plants were recovered from a back orchard at the same property earlier this month.
Two men, aged 28 and 61, were arrested and appeared before Gisborne District Court on cannabis charges. They will reappear on April 11.
Information on the drug seizure was not released at the time of the recovery because it was part of a month-long operation that covered the eastern police district from Central Hawkes Bay to East Cape.
The cannabis found in Gisborne was groomed and ready for the market, Senior Sergeant Mick Lander said.
"You are talking about a potential street value of $2000 for a mature plant, so this is a significant seizure," he said.
"There is plenty of talk around the proposed decriminalisation of cannabis - however, it is still a class C drug.
"Those operating on the wrong side of the law need to know we will continue to detect, apprehend and hold to account those involved in the illegal drug trade," he said.
Cannabis and firearms were recovered from six houses in Wairoa during the operation. Five people were arrested on cannabis and firearms charges. About 14,000 cannabis plants and 13kg of the drug were found across the eastern district during the operation.
Police arrested 185 people as a result of the raids.