Cannabis cultivation

This article presents common techniques and facts regarding the cultivation of the flowering plant Cannabis, primarily for the production and consumption of cannabis flowers ("buds"). Cultivation techniques for other purposes (such as hemp production) differ.

Cannabis belongs to the genus Cannabis in the family Cannabaceae and includes three species, C. sativa, C. indica, and C. ruderalis, (APG II system). It is typically a dioecious (each individual is either male or female) annual plant (life period: April–September).

C. sativa and C. indica generally grow tall (some varieties reach 4 metres, or 13 feet) and their females start the production of flowers rich in tetrahydrocannabinol (THC) (up to 29% by weight) as the season changes from summer to autumn. C. ruderalis is very short, produces only trace amounts of THC, but is very rich in cannabidiol (CBD), which may be 40% of the cannabinoids in a plant and is an antagonist to THC, and it flowers independently of the photoperiod and according to age. However, commercial cross-bred hybrids containing both ruderalis, indica and/or sativa genes exist (usually called autoflowering).

Cannabis needs certain conditions to flourish.

Soil is required, except for cannabis grown with hydroponics or aeroponics

The optimal day temperature range for cannabis is 24 to 30 °C (75 to 86 °F). Temperatures above 31 °C (88F) and below 15.5 °C (60F) seem to decrease THC potency and slow growth. At 13 °C (55F) the plant undergoes a mild shock, though some strains withstand frost temporarily.

Light can be natural (outdoor growing) or artificial (indoor growing).

Under artificial light, the plant typically remains under a regime of 16–24 hours of light and 0–8 hours of darkness from the germination until flowering, with longer light periods being conducive to vegetative growth, and longer dark periods being conducive to flowering. There is an ongoing debate over the necessity of a "dark period" for vegetative growth. It has been suggested that, when subjected to a regimen of constant light without a dark period, cannabis begins to show signs of decreased photosynthetic response, lack of vigor, and an overall decrease in vascular development. Typically, flowering is induced by providing at least 12 hours per day of complete darkness. Flowering in cannabis is triggered by a hormonal reaction within the plant that is initiated by an increase in length of its dark cycle, i.e. the plant needs sufficient prolonged darkness for bract/bracteole (flowering) to begin. Some Indica varieties require as little as 8 hours of dark to begin flowering, whereas some Sativa varieties require up to 13 hours.

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