Lightning Mc Queen

18/6 is optimum for autos and photoperiod plants in vegetative growth. Plants including autos do need "sleep" and cannabis, auto or photo, can only grow so much during any 24 hour period, and this growth tops out at about 18 hours, meaning running your lights any longer than 18 hours is basically a waste of electricity. Unfortunately Mr Deeunit has his facts in a muddle about the genetics of auto flowers and has offered some wrong information, which may shock him. Auto flowering plants are not ruderalis plants, they are photoperiod plants with an "infusion" of ruderalis genetics. Ruderalis plants flower "automatically" due to the very short summers in northern Russia, which is where most Ruderalis plants originate from and it is not because of almost no night hours in that part of the world during summer. Being able to grow, flower and produce viable seeds in a short summer, often not exceeding 6 weeks of optimum growing weather, has lead to ruderalis plants developing/evolving to flower as soon as they are old enough, roughly 3-4 weeks of age, giving another 4 weeks or so for seed maturation before the cold weather returns. Hope this helps and clarifies a few "facts" for you too,........ Organoman.

Its only Autos that you light for 20hrs and this can be all the way through its life."Normal" female seeds that they call photoperiod are given 18hrs in veg and 12hrs during flower.The plant cant use more than 17 and a half hrs of light it then needs 12hrs of darkness to flower.This is what happens in nature.The year starts to come to an end and the light hours get shorter.The Autos come from the northern hemisphere where they have very little or no darkness that's why they don't need a dark period to flower.You can give them 24hrs light but your lighting needs a break and they say its good to give the plant a break but thats debatable.So how people on here can give you bad advice.People should stick to what they know.If I didn't know the answer for sure then a wouldn't of answered the question.You can take this info to the bank my friend,its the facts,lol.

People do it because they say giving a plant 24-hour lighting can make it grow much faster, but too much light can interfere with growth, flowering, dormancy, so to me it doesn't make sense either.

More light = more photosynthesis