To force the cannabis plant into flowering it needs a dark period of at least 12 hours per day. If it receives any light during this time the flowering process will be disturbed. It can even revert back into the vegetative stage.
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More lighting related terms:
Lighting | Light cycle | Light shortage | Light distribution | Light spectrum | Blue light | Red light | Nanometer | Light tight | Lumen | Lux | Reflecting light | Lamp height
HPS lights | HPI lights | LED lights | Compact fluorescent lights