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How long should you have your lights on for optimal growth - Growbox tips


If you are in the process of trying to set up your grow box for initial grow cycles, you may be wondering about one of the big things that people often talk about when they talk about hydroponics -- what about light?

Growers face all kinds of questions about light. They have to make sure that plants get the right spectrum and intensity of light. But what about the amount of light, or how much light they get over the duration of a given day?

Light and Dark Cycles

Typically, growers set up light schedules for plants. These consist of light and dark times of the day or night, where plants get a defined number of hours of the day in the light, and the rest in the darkness.

The idea is that the plant circadian rhythms respond to an influx of light, and that plants on some level understand the difference between night and day. But although the natural night and day is around a 14 hour and 10 hour split, depending on time of year, hydroponic light and dark cycles are often quite a bit different.


A lot of growers use an “18/6” light cycle -- that is, they keep plants in the light 18 hours and let them rest the other six hours in darkness. Many growers claim that this is the best light cycle for plants because it provides them with some relatively brief chance to develop in the absence of light. Some claim that root systems grow better in the darkness, or that they get a certain natural benefit from the six hours that the lights are not on.


Then there's actually quite a bit of controversy about moving to a “24/7” or “light all the time” schedule. Other growers contend that plants actually don't need any darkness at all, and that root systems develop below the ground, where it's always dark. Of course, growers have to look at the specific makeup of a grow box or other grow system, where light may infiltrate the bottom of the system or the place where the root systems are, especially if they're sitting in reservoir water.

So the bottom line is that a lot of growers use quite a bit of light -- more than the average natural day. But not all of them leave the lights on all the time, because there's the common idea that plants can get some rest during the dark part of the cycle. Growers may also use different strategies for both vegetative and flowering phases of the plant cycle.

For much more, check out everything that retailers and manufacturers offer, including automated timers to help you keep light and dark cycles consistent. Take care and happy gardening!

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