Hemp, Annual, biennial or perennial? + photoperiod

Besides the large scale production of hemp, it is concidered a weed in many places. Weeds are characterised by their purpose to grow as fast as possible until ready to produce seed. After dispersing the seed, the plant die back down and have full filled their function. Hemp is a annual plant which is common for weeds. But there are exceptions, many weeds are biennials or even perennials.
After 4-5 week, the male plant are fully matured and disperse their seed for one week after which they die back. the female will the be fertilized and later on harvested.

Hemp is the only annual with male and female flowers on seperate plants. It is assumed that hemp was originally an short-lived perennial but as the climate changed in which they were propegated, they changed to annuals.

Hemp plants are in general photoperiod sensitive. The exception to the rule is the hemp variety that grow close to the equator. If hemp does not have long periods of uninterrupted darkness the plant will not flower. Shorter photoperiod cause early flowering and                   restricting yields in industrial hemp.



Figure. 1 Hemp growing besides the road



Bibliography:
http://www.tandfonline.com/doi/abs/10.1080/15440478.2013.846840?journalCode=wjnf20
http://www.hemp-technologies.com/page83/page83.html
http://www.cannabisculture.com/content/2005/09/23/4515

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