Marijuana indoor light schedule

Discussion in 'General Indoor Growing' started by Gartner, Apr 13, 2011.

  1. Gartner

    Gartner New Farmer

    I see lots of variations people are using during the vegetation period ranging from 18 to full 24.
    What is the light cycle during vegetation period, I need it from the experianced people, i have read in articles, as i dont want to do experiment on my buds..
    Its better to get knowledge from the experts...




    :harvest:
  2. motherlode

    motherlode Well-Known Farmer

    I use 18 for veg since the early 80's

    supposedly you get 20% faster growth with 24 hour veg - but I have never witnessed that - just a bigger pge bill
  3. HookedonPonics

    HookedonPonics Well-Known Farmer

    either will do fine, i prefer 18 on 6 off. also doesnt hurt to read around the forum first theres plenty of threads that will send you in the right direction if your trying to get into gardening. good luck bro :passingjoint:
  4. paulycali

    paulycali Well-Known Farmer

    I do 24hr veg because more light equals faster growth therefore bigger plants in less time

    :harvest:
  5. smokestack23

    smokestack23 Farmer

    I've always used 18. You can veg with anything from 18 to 24hrs of light but I wouldn't do less. IIRC I had a friend back in the day who vegged 10on 2off though. Not sure why or what the advantage was supposed to be. Anyone know?

    Now, what I'm about to say has no real basis in science or horticulture that I know of...just my own own goofy thinking.

    The way I see it...plants will sleep/rest for part of the day whether the lights are on or off. I personally have never noticed any significant increase in growth using 24 over 18hour days so I made up the part that they must be sleeping for about 6 hours with or without light. So, why spend money to waste power to run lights for an extra 6 hours per day that the plants probably can't use? we ALL have to sleep some time.?

    IF on the other hand, I noticed a 30% increase in growth by going 24 instead of 18, you bet I would.

    Also, just so you're thinking properly, and you already might know this...it isn't the shortened light cycle (from 18 or 24 to 12) that triggers flowering it's the UNINTERRUPTED 12 hours of complete darkness that triggers it. There IS a difference.

    That helps to explain why 10/2 would work for veg. Also opens your mind up to even other possibilities like 18hour light cycle in flowering.
    You know...if they can stay awake and growing for 18 hours, why not do 18/12 (with a digital timer of course based on a 30hr day) during flowering? They'll get the 12 hours of dark that they need to flower plus they can grow at their full potential for 18 hours like in veg.

    Well there are a few reasons not to such as..what if you want to have a flip flop of 2 rooms flowering...one room on for 12hours and the other room comes on for 12 hours when the first goes out. Or the fact that you might get more growth per "day" on 18/12 but the days are now 30hours long and in the end, you'd probably end up taking the same amount of hours in the end.

    It does help to think that it's the 12 of uninterrupted dark as opposed to the shortened day cycle though.

    hope all that makes some sense and is somewhat helpful. Again...whether or not any of it is scientifically true..I don't know so take my info with a grain of salt.
    YMMV
  6. ScarabGlass

    ScarabGlass New Farmer

    Marijuana can photosynthesize 24 hours a day. It doesn't rest, but it does take time for it to build new plant tissue and absorb nutrients to form that tissue. I think stressing the plants with a 18/12 would not be a good idea. I'm no expert but the mother and father were on a 24 hour day. I think it would be hardwired into the cannabis dna that it runs on earth time(24hr days). Like you said though..."a grain of salt."
  7. St3ve

    St3ve Active Farmer

    24hrs for clones, 18 for veg, 12 for flower. Thats how I always do it.

    If I get behind on veg I bump up there light more and yes they will grow a little faster. Not enough IME for all the extra electricity so thats why I only do it if I'm behind.
  8. Fred

    Fred Premium Farmer

    I used 18hrs for years and had no problems. For the last couple years I've run 24hrs with no problems. It's never dark so I can work whenever I want to.

    I wonder if the temp change when the lights go off will cause plants to stretch some. I know in flowering it does. Anyway, I have considered going back to 18hrs but hate all those timers...:)

    fred
  9. Gartner

    Gartner New Farmer

    24hrs veg, will do faster growth, but how is your yield,
    the health of the flant,
    also what is the dark cycle, during vegetation period..
    Thanks master....



    :harvest:
  10. Gartner

    Gartner New Farmer


    then how do the outdoor growing works...
    outdoor growing gives better yield too..
  11. tattoojim

    tattoojim Guest

    weed flowers at night rite? lots of info spread alover about this. seems to b the verdiect was it needs no darkness in veg and it was benificial to veg 24 hours..
  12. smokestack23

    smokestack23 Farmer

    Gartner,
    Outdoor plants can yield better if the nutrients and moisture are optimal because the sun is so much better than any lights we can use indoors. It's also pretty hard to beat the ventilation that outdoors provides.

    Sorry for all the confusion. The easy and short answer to your question is:
    Veg: 18 hours lights on, 6 hours lights off. Some growers prefer to leave the lights on for 24hours. Some people will tell you that 24hrs doesn't give enough extra growth to justify using electricity for 6 additional hours/day.

    For flowering 12 hours lights on and 12 hours lights off. It's the 12hours of uninterrupted darkness that induces flowering not the shortened photoperiod(light cycle).

    I think THAT info is pretty much universal and not much argument should arise.
  13. Seamaiden

    Seamaiden Moderator Staff Member

    I've done 18/6, 24/0, and now, because I'm mainly an OD grower, I use a staggered (aka interrupted) photoperiod that matches my daylight hours in April. This way they don't flower out immediately when put out. If you don't, then you need to get them as big as you can before you put them outside or they'll flip into flower immediately upon experiencing such a greatly reduced photoperiod.