Safer® Hydro FAQ: Should Grow Lights be Left on all the Time?
Q: If I give my plants light all day, they'll grow faster, right? I figure all I have to do is leave the lights on and they'll become monsters!
A: In general, you should not leave grow lights on 24/7. Plants need a light-dark cycle to develop properly. It’s believed that they truly do “rest” during periods of darkness, and probably use this time to move nutrients into their extremities while taking a break from growing.
With that simple fact in mind, also know that most plants expect to get at least 12 hours of light a day, all at varying intensities. Check your plant guides for the specific sunlight needs of your hydroponic plants as they grow and bloom.
Of course, you can make sure your plants always get the right amount of light by setting up a timer on the lights over your hydroponic garden. With a timer, you never have to worry about remembering to turn them off or on.