A cannabis plant is a controlled plant for the purposes of the Controlled Substances Act 1984 and it is an offence to have or grow any number of them. The Act and related regulations look to distinguish between drug users and producers or suppliers, therefore the number of plants that an individual has or grows will directly affect the charges and penalties faced.
A simple cannabis offence, being the cultivation of 1 cannabis plant without artificial enhancement, can be expiated by a police officer who issues an on the spot fine. The cultivation of not more than the prescribed number of cannabis plants, being 5, is guilty of an offence and faces a maximum penalty of $2,000 and/or imprisonment for 2 years. The cultivation of more than 5 cannabis plants without artificial enhancement, or one or more cannabis plants with artificial enhancement, is guilty of an offence and may face a penalty of up to $5,000 and/or 5 years imprisonment. The penalties increase if the number of cannabis plants is of Trafficable Quantity (10), Commercial Quantity (20), or Large Commercial Quantity (100).
s 7 Controlled Substances (Controlled Drugs, Precursors and Plants) Regulations 2014
s 33K Controlled Substances Act 1984