10-14 days after starting the 12/12 light cycle, pollen sacks will begin to develop on male marijuana plants.
The photograph shows a flowering male marijuana plant.
If you grow marijuana, either hydroponically or with soil, the male plants must be removed before pollen is released.
If allowed to release pollen, a male marijuana plant will pollinate all the nearby female marijuana plants. Pollinated females will use energy making seeds, rather than producing THC.