Its seeds are chiefly used to make hempseed oil which can be used for cooking, lamps, lacquers, or paints. They can also be used as caged-bird feed, as they provide a moderate source of nutrients for most birds. The flowers (and to a lesser extent the leaves, stems, and seeds) contain psychoactivechemical compounds known as cannabinoids that are consumed for recreational, medicinal, and spiritual purposes. When so used, preparations of flowers (marijuana) and leaves and preparations derived from resinous extract (e.g.hashish) are consumed by smoking, vaporizing and oral ingestion. Historically, tinctures, teas, and ointments have also been common preparations.
The flowers of the female plant are arranged in racemes and can produce hundreds of seeds. Male plants shed their pollen and die several weeks prior to seed ripening on the female plants. Although genetic factors dispose a plant to become male or female, environmental factors including the diurnal light cycle can alter sexual expression. Naturally occurring monoecious plants, with both male and female parts, are either sterile or fertile but artificially induced "hermaphrodites" (a commonly used misnomer) can have fully functional reproductive organs. "Feminized" seed sold by many commercial seed suppliers are derived from artificially "hermaphrodytic" females that lack the male gene, or by treating the seeds with hormones or silver thiosulfate. In the case of production related to recreational use of Cannabis, the process of "cloning" provides the grower with DNA identical female plants eliminating the need of seeds for the growing process.
A Cannabis plant in the vegetative growth phase of its life requires more than 12–13 hours of light per day to stay vegetative. Flowering usually occurs when darkness equals at least 12 hours per day. The flowering cycle can last anywhere between nine to fifteen weeks, depending on the strain and environmental conditions.
In soil, the optimum pH for the plant is 6.3 to 6.8. In hydroponic growing, the nutrient solution is best at 5.2 to 5.8, making Cannabis well-suited to hydroponics because this pH range is hostile to most bacteria and fungi.
Broadly, there are three main Cultivar Groups of cannabis that are cultivated today:
Cultivars primarily cultivated for their fiber, characterized by long stems and little branching.
Cultivars grown for seed which can be eaten entirely raw or from which hemp oil is extracted.
Cultivars grown for medicinal or recreational purposes. A nominal if not legal distinction is often made between industrial hemp, with concentrations of psychoactive compounds far too low to be useful for that purpose, and marijuana.
Although the main psychoactive constituent of Cannabis is tetrahydrocannabinol (THC), the plant is known to contain about sixty cannabinoids; however, most of these "minor" cannabinoids are only produced in trace amounts. Besides THC, another cannabinoid produced in high concentrations by some plants is cannabidiol (CBD), which is not psychoactive but has recently been shown to block the effect of THC in the nervous system. Differences in the chemical composition of Cannabis varieties may produce different effects in humans. Synthetic THC, called dronabinol, does not contain CBD, CBN, or other cannabinoids, which is one reason why its pharmacological effects may differ significantly from those of natural Cannabis preparations.
Cannabis sativa has a higher level of THC compared to CBD, while Cannabis indica has a higher level of CBD compared to THC.[dubious– discuss]Cannabis strains with relatively high CBD:THC ratios are less likely to induce anxiety than vice versa. This may be due to CBD's antagonistic effects at the cannabinoid receptors, compared to THC's partial agonist effect. CBD is also a 5-HT1A receptor (serotonin) agonist, which may also contribute to an anxiolytic-content effect. This likely means the high concentrations of CBD found in Cannabis indica mitigate the anxiogenic effect of THC significantly. The effects of sativa are well known for its cerebral high, while indica is well known for its sedative effects which some prefer for night time use. Both types are used as medical cannabis. Indica plants are normally shorter and stockier than sativas. They have wide, deeply serrated leaves and a compact and dense flower cluster. The effects of indicas are predominantly physical and sedative.
^ abcdefghiNovak J, Zitterl-Eglseer K, Deans SG, Franz CM (2001). "Essential oils of different cultivars of Cannabis sativa L. and their antimicrobial activity". Flavour and Fragrance Journal16 (4): 259–262. doi:10.1002/ffj.993.