What is the Critical Photoperiod for Cannabis?

January 16, 2019

The critical photoperiod for female cannabis plants is about 12½ hours, with about 13 hours for male plants. A traditional lighting regimen to bring plants into flower is 12 hours of dark followed by 12 hours of light.

Midsize vegetative cannabis plants
PC: Dan Heims

The dark period must not be interrupted with any light, and it typically takes two weeks under this photoperiod regimen for plants to bud. You will need an enclosed growing space such as a grow tent, a sealed closet space, or a grow room.

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