COPS AND CROPS: RNZAF personnel accompanied by constables from the Nelson Bays Police area recover cannabis in the Tapawera area last year.

Police have received hundreds of tip-offs about cannabis growing in Nelson and Marlborough.

A police spokeswoman said the growing season was well under way, and the annual drive to root out cannabis growers and destroy their crops was in the information-gathering stage.

"Hundreds" of people had called police with information about cannabis, she said.

High times: Police found this cannabis plot in the Marlborough Sounds during an annual cannabis operatio

Marlborough cannabis operation co-ordinator Senior Constable Beau Webster, of Blenheim, said as of December 31, police had recovered 250 cannabis plants and 5 kilograms of dried material.

Some of the plants had been recovered through warrants and some had just been found "out in the wop-wops", he said.

The cannabis operation runs for about five months, but police were always on the lookout for crops.

"May is the end of the cannabis-growing season, but in this climate, you could grow it all year round," Mr Webster said.

He encouraged people to use the Crimestoppers line to report suspicious activity.

Tasman cannabis operation co-ordinator Sergeant Rob Crawford, of Nelson, said rural people were at risk if cannabis was grown in their area.

"We generally see an increase in dishonesty . . . which is associated with people growing drugs in an area," he said.

"Electric fence units and tools from farm sheds are particularly vulnerable to theft and poaching of stock is a common problem."

People going into the bush with gardening tools and water bottles was a bit of a giveaway.

Anyone who lived in a rural area or who went tramping or camping could easily come across plots or growers tending their crops.