How many hours do you use grow light
Light is definitely one of the most important factors during their growth, but darkness also indispensable for plants, like human, they also need rest. During the day, plants absorbed the light for photosynthesis to produce energy. At night, plants will break the energy down for growth and flowering.
Different type of plants have different light cycle, but most plants would love 12 to 16 hours of light per day. During growth, most people would set the light cycle is 18/4 or 16/6 (which is 18/16 hours of light, and 4/6 hours of darkness). During flowering, keep the lighting cycle 12/12.
No one would love to work 24 hour per day-so do plants! Remember give your plants darkness to rest!