the 18 hour day/night grow schedule???

Discussion in 'Growing Marijuana Indoors' started by az2ct, Jun 1, 2009.

  1. i'm extremely interested in trying this out. i wanted to know if this sounds possible or if this sounds like shit.

    here's the theory though so you guys can read it and give me feedback
    note: this is NOT my theory.

    The Theory
    The theory behind the 18 hour Day/Night cycle is that during a normal 24 hour light cycle plants will usually achieve high growth rates peaking at 100% capacity during the first 50 - 60% of the day. The growth rates will then diminish rapidly and the last 20 - 30% of the day achieves minimal growth. So by reducing the length of the day we are triggering an increased growth mode where the growth rates are at their peak for the majority of the day. This effectively achieves a very fast growth cycle with full yield potential.

    NOTE: To achieve these incredible growth rates it is important to provide maximum light intensities and CO2 enriched conditions. The recommended lighting is 600W per square metre.

    The Cycles
    Vegetative Cycle - Lights ON 14 hours Lights OFF 4 hours Flowering Cycle - Lights ON 6 hours Lights OFF 12 hours The Benefits The growth achieved during an 18 hour cycle can be the equivalent to that achieved during a 24 hour cycle. So by running 18 hour cycles the same growth and yield can be achieved in 75% of the time.
    Reduced day lengths also mean reduced power consumption. Grow more and use less power. Who can argue with that?
    For example, an average crop grown from seed using a 24 hour day/night cycle will have a 4 weeks grow cycle and an 8 weeks flower cycle. This equates to 28 days @ 18 hours a day and 56 days @ 12 hours a day = 1176 hours of light over 12 weeks.

    An accelerated crop using an 18 hour day/night cycle will achieve the same yields using a 3 week grow cycle and a 6 week flower cycle. This equates to 21 days @ 14 hours a day and 42 days @ 6 hours a day = 546 hours of light over 9 weeks resulting in a 40% reduction in power consumption and a 25% reduction in crop time.
  2. it sounds like a really good idea. i think i'll be the one to take the plunge and try it on some mids
  3. id like to know what the effects of using a non 24hr cycle would be. it seems like a gamble since plants evolved over millions of years with 24hr.

    if there turned out to be no drawbacks, are there any timers one can use for such a cycle?
  4. yea but, i think i'm gonna go with the 12/12 from seed technique. its farless complicated and has mnany benefits to it. i just wonder if i used 6500k's or 2700k's since i'm starting the seeds off at 12/12
  5. does anyone know?????

  6. If you are going right into 12/12 then use the 2700k lights. No veg means no need for 6500k.
  7. thanks man!!!! i'm gonna get the other four 42w 2700k's i need then. i should be able to squeeze 4 plants running with 252w of 2700k cfl, right???
  8. well damn so your not going to try out your theory??? it would have been cool to see what happens.
    tell me more about straight 12/12 does the plant just start to flower after reaching maturity?
  9. yea bro... it wasn't my theory. secondly, it would be very hard to turn the light on and off or even to set the timers every day to make sure your day stays 18 hrs. thirdly,(lol) with straight 12/12, it has been proven and resluts have been shown and with some strains you end up saving about the same amount of time. you can fit more plants into your space and utilize your light to the max. doing straight 12/12 also saves a ton of energy on top of the time your saving, being that you cut down on countless hours of the "on" period. i have a small closet space that wouldn't be able to fit more than 2 decent sized plants max. using this method allows more plants and it keeps all plants short. sativas will grow larger than indicas still but at a very managable height. that opens the door for me to grow sativas strains without having to worry about height or space.
    here's a link of the method, its actualluy very popular:
    12/12 From Seed: A Different Way To Grow - International Cannagraphic Magazine Forums
  10. check the bottom of the first page guys, you'll see what i'm talking about.
  11. I don't know of a timer that you could program to do that.

    As for the theory -- who knows?
  12. there is one company that sells it. there from australia. there the one that came up with the whole theory but it could be a bunch of bull. that's why i wanted to try it. but the timer is like $300 aka no can
  13. you can do it with a standard digital timer.

    I ran a 30 hour day for a while....its not hard to do. Just get one with like 20 on/off settings, and set each week manually.
  14. like one from home depot i'm guessing. now that i discovered the 12/12 from seed method, i'm more apt to try that one b/c of it's ability to allow you to use more of your space efficiently. who would mind a extra plant here and if anyone knows about a thread on 12/12 from seed grow, please let me know. thanks. as soon as i get the rest of the 2700k's and a ph meter i'll be doing a journal. from some ungodly reason, ph has killed pretty much every single one of my plants. i'm a new grower BTW. but i have a grow going right now that's not looking too hot. 1xPPP 1xaurora indica and two haze seeds that turned out to be duds=( the aurora has been hanging on with the ph problems but its almost dead and if it were to survive, the best i could wish for is a shitty the PPP is the healthiest. when i transplanted it i guess i tore some of the roots. like a good amount, i know it was a noob mistake. so some of the leaves have been slowly dying but its not so bad. just needs to get the roots back. if this grow goes to hell which is a good chance i'm gonna stop for a couple of weeks and get everything i need to grow some healthy buds. i plan on doing the 12/12 every grow from then on. i don't want alot of weed, just quality.
  15. Works like a charm, Bloom almost 6 weeks, great result. Cut costs in half and reduced overall time. Now if I go led I'll cut the costs in half again.

    Grow is simply stunning.

    I use a Sentinel DRT-1 Digital Recycling Timer.

    Feed to use through Smart Valves in Auto Pots, using scoria as a medium, no flushing or continual nutrient maintenence, no pumps or timers

Share This Page