Photoperiod: Veg @ 18/6, 20/4 or 24/0

I'm unsure if this kind of query has been raised before. If it has forgive me for repetition and I'll be happy to follow any links to existing threads.

I'm vegging under 1 600W HPS for 18 on 6 off. Does any one know the science behind 18/6 as oppose to 20/4 or 24/0? Please Share!!

I've read on other sites threads that offer differing opinions. Some people swear by 24/0 while I have never tried any other regime besides 18/6 unless it was by accident where timers didn't switch off the lights for over a week. What do the experienced farmers of Cannabis.com reckon?

I'm thinking of taking cannabis cultivation to another level and studying for some kind of botanical accreditation..

16-24 hours of light is all that is needed for vegetative growth cycle. You can put it on 24 hour light but it will cost more energy to run the light 24/7. Most people do 18/6 to save on energy.

there is a thread on here that shows that 18/6 grows roots better than 24hrs

Quote:

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Originally Posted by Paht_Hed

16-24 hours of light is all that is needed for vegetative growth cycle. You can put it on 24 hour light but it will cost more energy to run the light 24/7. Most people do 18/6 to save on energy.

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It surely cannot be just the financial/energy saving aspect?

Quote:

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Originally Posted by gt420z

there is a thread on here that shows that 18/6 grows roots better than 24hrs

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Thanks, I shall search around. The opinions that I sourced from elsewhere mention the same theory with regard to root formation. Still wondering I anyone else has experience of comparrisons...

I think you'll find "hard evidence" difficult to come by. It's my belief that most ideas that may show a worthwhile gain in yield are the ones that get documented. But since there is no "easily" discernible difference found between veg. light schedules, no one has bothered to do a real scientific research study. Most folks just go by the accepted guidelines and concentrate on maximizing other variables that make a larger difference over the course of the grow.
So, I also believe the choice is based more on energy savings than on raw results obtained by that choice.

Most people grow with MH/HPS who use a 18/6 schedule b/c they are so damn expensive to run if you have say 2 1000 watt setups. I run 10 cfl bulbs and keep mine on 24 hr light.

During the propagation stage, lights should be left on as long as possible, up to 24 hours per day. Strong initial growth will make the young plants healthier and more resistant to disease, ultimately providing better yields. As the plants begin to mature, however, light duration should be reduced.
Plants use periods of darkness, too. During dark periods, plants continue to take in oxygen and give off carbon dioxide in a process called respiration. During this time, the plant uses some of the energy that was stored as sugars during photosynthesis, producing proteins, hormones and other complex products. Therefore, lighting mature plants more than seventeen and a half hours per day will not increase production significantly, since photosynthesis will slow down after a certain number of hours. I have been using this method or years and see great results. 18\6 is a easy number to remember.

Good info there growbe. And might I say, Welcome to Cannacom!

Thanks for all of your replies.

With this information I am deciding to run my veg roomusing both 18/6 and 24/0.

I will veg my mothers with 18/6 most of the time. But when I fill the propagator with cuttings from the mothers I will run the lights @ 24/0 until the cuttings are rooted. Then once I see signs of all cuttings showing roots I shall revert back to 18/6.

I want strength and good root formation, so I will utilise both methods.