Prohibited plants

Offences involving prohibited plants

The cultivation or possession of prohibited plants, such as cannabis, is an offence.

It is an offence to:

  • cultivate
  • knowingly take part in the cultivation of
  • possess
  • supply

a prohibited plant.

What is included?

Cultivation is defined to include sowing seed, planting, tending, nurturing or harvesting.

Watering a plant, shading it from the sun, picking the heads off a friend's plant, even watering ungerminated seeds, all come within the definition of cultivation.

Possession of plants is also an offence under the same section and with the same maximum penalty as for cultivation. A charge of possession of prohibited plants would be laid where there was no evidence of any act of cultivation (such as planting or watering), but there was evidence of possession (again, requiring proof of knowledge and custody or control) of the plants.


The penalty categories for cultivating cannabis depend on the number of plants, not their gender or size. Cultivating a hundred seedlings that can fit into a baking tray is treated the same as cultivating a hundred mature female plants. Having 250 seedlings is regarded as more serious than having five big plants, even though the weight of the five big plants may be many times greater.

Higher penalties apply to offences involving the cultivation, supply and possession of a 'commercial quantity' of prohibited plants.

Defences to cultivation

It is a defence to a charge of cultivation of a prohibited plant if the accused can establish that they did not know the plant was a prohibited plant. The prosecution may rebut the accused's evidence by bringing, with leave of the court, evidence of any previous convictions.

Hydroponic cultivation

It is an offence to participate in the ‘cultivation by enhanced indoor means’  of cannabis plants. The offence requires the cultivation to be:

  • inside a building or structure and
  • involve growing the plant in nutrient enriched water or applying artificial light or heat or suspending the roots and spraying them with nutrient solution. 

Where the number of plants involved is more than 5, the maximum penalties are significantly higher than for an equivalent number of plants cultivated outdoors. 

For cases involving between 5 and 50 plants cultivated by enhanced indoor means, the prosecution must also prove the cultivation was for a ‘commercial purpose’. ‘Commercial purpose’ means intending to sell or believing that another person intended to sell the product. For cases involving 50 or more plants cultivated by enhanced indoor means, the prosecution does not need to prove a commercial purpose. 

Exposing a child to indoor cultivation

It is an offence to cultivate ‘a plant’ (note the singular) by enhanced indoor means and ‘expose a child’ to the cultivation process or to substances stored for use in cultivation. The penalties are substantial, with heavy fines and imprisonment possible even for one to four plants.

It is a defence if the defendant can prove that the exposure did not endanger the health and safety of the child. For these purposes, a child is defined as a person under 16.