Definition - What does Force Flowering mean?
Force flowering, also known by other names such as flower forcing and photoperiod manipulation, is a technique used by growers to increase levels of flowering hormones in marijuana plants. This is normally done by ramping down the number of daylight hours received by the plant. So, if we're talking about an indoor grow where the plant is in the vegetative stage of growth, receiving either 24 hours of light a day, or 18 hours of light a day and 6 hours of darkness, then in order to get most strains to flower a light cycle of 12/12 will force the levels of flowering hormones up so high that the plant produces reproductive parts, namely flowers.
MaximumYield explains Force Flowering
Some varieties of marijuana that are originally found near the equator can require from 12 and ½ to 13 hours of darkness to flower, but most strains only require 12/12. The simplest way to achieve this is by setting your 1000W High Pressure Sodium Freestanding Ballast in line through a timer before connecting it to your power supply. The timer is set to the desired photoperiod and allowed to operate without being altered, as it is important that the dark time be at the same time for each repetition of the cycle. The light cycle selected, be it 12/12 or 13/11 dark/light, must remain unchanged for eight to ten weeks in order for the flowering phase of the plant to complete and produce the most usable cannabis with fully developed trichome heads and biomass production.