Show me 2 plants, from the same mother, one in 24/0 and one in 18/6, and show me a big difference between them. My opinion is exactly that, an opinion, but I have tried both time periods on different grows. The only difference I find, is that the plants grow more. Not a lot, but more. Now, I havent looked at the roots when in the veg (but in the end at harvest, the roots are about the same size), but if the canopy is larger in a plant with 24 rather then 18, and its healthy, then it probably also has a root system to support that canopy. Plant is bigger = bigger root system.

That being said...I use 20/4 or 18/6, but not for the reasons of better root development or something like that. I use it because I believe there are more advantages to having some darkness then the advantages of light 24/7, even though I believe plants need light far more then they ever need darkness (veg state of course).

The advantages of 18/6 or something similar that I see, is that you greatly enhance your bulb's life, you wont need to water as much, your energy bill will be substantially lower if you have a lot of lights, you will have an easier time keeping things cool. I use 24/0 when I am vegging from clone for 1 week and then going into flowering.
Racerx Reviewed by Racerx on . roots and lighting question. Hi, my friend currently has a hydro setup that is on 18/6. From what I have read roots spend most of their time "searching" or growing during the dark hours correct? It is also well understood that MJ grows the best under 24hr or similar lengths of time. My question is; if this is the case, woulndn't it make sense to leave the light in the 18/6 cycle so that the roots still have 6 hours to grow during veg rather than a constant light cycle? Wouldn't this especially be the case for Rating: 5