Section 70 of the Drugs, Poisons and Controlled Substances Act 1986 provides an inclusive definition:
cultivate, in relation to a narcotic plant includes—
(a) sow a seed of a narcotic plant; or
(b) plant, grow, tend, nurture or harvest a narcotic plant; or
(c) graft, divide or transplant a narcotic plant.
In Grozdanov v The Queen  VSCA 94 the accused was charged with cultivating a commercial quantity of cannabis. It wasn't really possible to argue that the accused was unaware of the crop. Instead, the defence at trial was that the maintenance of the hydroponic system didn't amount to cultivation.
Neave JA [at 48, Mandie JA and Kyrou AJA agreeing] kept the definition wide, to be assessed case-by-case:
In my opinion, the ongoing maintenance of a hydroponic system which regularly delivers water and nutrients to a growing crop to foster its growth is not an activity associated with an activity listed in s 70, but comes within the words tend or nurture in paragraph (b) of the statutory definition (at least if done on a regular basis). Such an activity is analogous to manually watering a crop or putting nutrients on it. Accordingly, it is unnecessary to extend the meaning of ‘tend’ or ‘nurture’ to cover activities associated with tending or nurturing, in order to include the ongoing maintenance of the hydroponic system.
Because cultivation normally involves an activity which occurs frequently or regularly, one or two visits to premises to repair a hydroponic system would not necessarily amount to ‘cultivating’ a crop growing there, any more than turning on a tap on a hose on a single occasion, knowing that the hose was watering a cannabis crop, could amount to cultivating it. The appellant’s conviction did not require an extension of the definition in s 70 to cover activities associated with the listed activities.
For the purposes of this case, it is unnecessary to define the circumstances in which maintenance of a hydroponic system would fall within or outside the definition of cultivation in the sense of tending or nurturing a crop. As Buss JA said of the meaning of ‘harvest ‘ in the Western Australian Misuse of Drugs Act, whether an activity amounts to cultivation will depend on the facts and circumstances of the particular case.
The Court of Appeal decided that what the accused did could amount to cultivation. A further ground of the appeal argued that the trial judge had usurped the jury's function by effectively directing them that the maintenance of the hydroponic system did constitute cultivation, rather than could constitute cultivation. This ground was made out [at 74], and the conviction on those charges quashed.