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.
Paht_Hed Reviewed by Paht_Hed on . 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 Rating: 5