In nature, marijuana is an annual plant and usually lives only one season. This ranges from about five to 10 months. However, most varieties (except equatorials) are photoperiod sensitive. That means that they flower based on the number of hours of uninterrupted darkness. If there aren?t long periods of uninterrupted darkness, the plant will not flower. For instance, a plant kept in a living room or kitchen, where the lights are likely to be turned on during the evening may grow vegetatively for years.
Cannabis is the only annual with male and female flowers on separate plants. All other dioecious (that is, gendered) plants, including its cousin, hops, are perennials. Cannabis was probably originally a short-lived perennial. As the climate changed from subtropical to more temperate in the Himalayan foothills where it originated, it adapted into an annual. I suspect that in some sub-tropical and tropical areas there are still cannabis plants that live for several seasons. They flower each fall and then go into a period of slow growth. When spring arrives they start growing vegetatively again, then flower once again in the fall.
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