18/12 light cycle

Hey all, i was wondering if anybody has had experience with a 18/12 light schedule. Of course, this is assuming that plants need 12 hours of darkness to induce and to stay in the flowering stage, which is debatable. I found a section in September/October 2007 issue of Indoor Gardener Magazine titled "Need to Reduce That Monthy Power Bill?" under the Notes&News (page 10 for those who read Indoor Gardener). Here's a type-up of the section...

"Is the power bill giving you the monthly heart attack? it may be time to start using your head to cut that power usage down to size. Simple steps for users of Harvest Master climate controllers have proven to produce a massive benefit. These controllers have "any length" day/night timers and come standard with a 'fast flowering' cycle (18 hr per day). This allows a 18 hr Day period, followed by 12 hours of night, to ensure your plants stay locked in 'flowering' but every day you gain 6 hours for new growth room to start a new day. In 3 days, your plants have had 4 days! In 3 weeks your plants will have had 4 weeks! Simply put, each month, your lights (and A/C units and dehumidifiers) will be on for just 240 hours in fast flowering mode, instead of the usual 360 hours in 12/12 flowering cycles. This is a massive drop on 34% of the power usage, just like that." - T.O

Apparently this helps with power, but I don't care about that. What I was wondering, has anybody tried this method? Will it work for cannabis like other plants? Is the yield really affected? Is it worth it? I'm looking for the most effective, cost efficient system to grow for personal use.

sounds good in theory, but where do i get said timer?

i checked out the website Indoor Gardener offered, www.harvest-master.com and found these timers too damn expensive (the one i saw was $900). they arent just timers either, they regulate co2 and operate monitor your grow supposedly. definately something for a real avid indoor gardener, not for the small personal gardener of herbs and spices. maybe a digital (sorry if its the wrong name, i dont know the real name) more expensive timers with more settings would work fine as well. after all, im just curios if anybody has had experience with a 18/12 light cycle.

18/12 ? am i stoned or what but how the hell u have 30hours a day?

read the original post and you would understand

oh now i get it. timer dont care about days. it just works 18hours on and then 12hours off.

sounds very neat. hope to hear more

anybody???

Maybe I'm still tired but your math doesn't seem to work. 18+12=30 so it would take 4 calender days to achieve 3 days for the plants. Now there was talk of using an 18hr day. Which was 6/12. They believe the plant absorbs all its energy within the first 6 hours of light and the rest is a waste. that would achieve more days per week to say. and a quicker harvest. but i believe yields suffered.

Not sure.. HELL I don't even have one grow under my belt... But i recall reading something like this before.. Search the forum.

I'm sure others know more on the subject.


Lr8,
D

Dubbydubdubs said:

Maybe I'm still tired but your math doesn't seem to work. 18+12=30 so it would take 4 calender days to achieve 3 days for the plants. Now there was talk of using an 18hr day. Which was 6/12. They believe the plant absorbs all its energy within the first 6 hours of light and the rest is a waste. that would achieve more days per week to say. and a quicker harvest. but i believe yields suffered.

Not sure.. HELL I don't even have one grow under my belt... But i recall reading something like this before.. Search the forum.

I'm sure others know more on the subject.


Lr8,
D

Click to expand...

you have failed to understand the 18/12 light cycle. it may be hard to understand, and if you read up a few posts to the first person who said my math wrong, you can see you clearly misunderstood me. the reason why i started this thread was to find information about this method of growing, and there was only one reference to 18/12...

omega7 said:

Using an 18/12 light cycle will speed up flowering time. You can shave a week or 2. Combine that with hydro and you could shave quite a bit. If you are already doing hydro then just go with a 18/12 light cycle. You will need a programable digital timer for that, one with 7 days programable.
EDIT: you only want to play with the light period, not dark. You want to stick with 12 off.

Click to expand...

it means that there will be 18 hours of light, followed by 12 hours of dark. 30 hours completes one "day." this allows the plants to stay flowering, but also gaining 6 more hours of light per "day."
lets look at a week (seven days) of each method by comparing the hours of light, while keeping a 12 hour darkness period starting at 12:00 am Sunday - 12:00 am Sunday.

12/12
In one week of 12/12 you will have 84 hours of light, 84 hours of dark.

18/12
This is the one that people are having a hard time grasping. I will try my best to explain it. So, I will go day by day for one calendar week starting at Sunday midnight (12am).
"Day 1"
Sunday lights on 12:00 am - 8:00 pm, Lights off 8:00 pm - 8:00 am Monday
18 hours of light, 12 hours of dark.

"Day 2"
Lights on Monday 8:00 am - 2:00 am Tuesday, Lights off 2:00 am - 2:00 pm Tuesday.
18 hours of light, 12 hours of dark.

"Day 3"
Lights on Tuesday 2:00 pm - 8:00 am Wednesday, Lights off 8:00 am - 8:00 pm Wednesday.
18 hours of light, 12 hours of dark.

"Day 4"
Lights on Wednesday 8:00 pm - 2:00 pm Thursday, Lights off 2:00 pm Thursday - 2:00 am Friday
18 hours of light, 12 hours of dark.

"Day 5"
Lights on Friday 2:00 am - 8:00 pm Friday, Lights off 8:00 pm - 8:00 am Saturday.
18 hours of light, 12 hours of dark.

"Day 6"
Lights on Saturday 8:00 am - 2: am Sunday, Lights off 2:00 am - 2:00 pm Sunday.
18 hours of light, 12 hours of dark.

Now in order to satisfy the 168 hour week, we have to cut off 2 hours of the light time on the last day. So, in one week with the 30 hour cycles, your plants will see 106 hours of light, and 62 hours of dark. THE DARK CYCLE HAS TO, MUST ALWAYS BE 12 HOURS TO KEEP PLANTS FLOWERING.

Recap
One week (168 hours) of 12/12 yields 84 hours of light, 84 hours of dark in one calendar week (168 hours).
One week (168 hours) of 18/12 yields 106 hours of light and 64 hours of darkness.
Keeping plants locked in flowering by the 12 hour dark cycles allows more day time for the plants to produce, shown to reduce the number of weeks in flower. what i'm trying to get at is, DOES ANYBODY KNOW ANYTHING ABOUT THIS??

sorry for all the banter, im blazed right now and in a bad mood. let me hit this once or twice and ill be twice as nice...

i hope you all understand by now, now, does anybody have experience with this???

high times q/a 2004-03-29

A: Dear Grower, The Cannabis plant requires 12 hours of darkness to flower properly. You can't shortchange the plants on darkness as it's the key to the flowering process. Many growers have experimented with a longer daylight period, say 18 on 12 off with inconclusive results, but the plants simply must have the full 12 hours of darkness to initiate and continue flowering. There are timers that can operate on schedules other than a 24 hour day, but they can be difficult to find and are expensive. Save your dough and just get a simple appliance timer for around $15. Set it for 12 on 12 off and be patient. It'll be worth the wait.

Click to expand...

over at ozstoners:

bufo marinus
Jul 24 2007, 09:15 PM
I recall reading a thread on Overgrow regarding 18 on 12 off. The extra hours of light did produce more yield, but the length of time it added to the grow did not improve the overall amount grown when averaged out over a year.

Click to expand...

http://www.cannabis.com/growing/lighting-How_do_i_manipulate_the_photoperiod_for_larger_yields.html

Lighting
How do I manipulate the photoperiod for larger yields?
[DISCLAIMER]: This information is provided as experimental data and not fact.

The only photoperiod manipulation from years of experiments that offered discernible improvements was the following photoperiod adjustment made for 1 or 2 calendar weeks at the point of maximum flowering rate: Daylength of 21 hours, 36 minutes with a dark period of 12 hours. To accomplish this, you need a 7 day, 24 hour digital timer. During a 7 day calendar week on Earth, the "sun" only cycles 5 times. This permits easily switching back to the regular 12/12 at your discretion. You may want to only alter during peak flower production to stimulate the plant's metabolism. Using this photoperiod throughout the flowering cycle will cause this:

A variety that takes 49 days of 12/12 to mature, won't see 49 - 12 hour dark periods under 21:36/12 until almost 10 calendar weeks have passed.

The total increase in light energy is almost 80%, which will produce larger yields, if all of your other enviromental conditions are kept optimal.

The total increase in flowering period is only 40%, half the potential room for improvement. This means you don't have to be perfect to win out.

Selective application of the 21:36/12 photperiod for only 1 or 2 weeks extends the wait only 2 to 4 Earth days, which makes up the missing 2 complete day and night cycles each week on Planet Ito. This permits the additional light energy to be provided without purchasing additional equipment or overloading existing circuits, which maximizes the existing system's capabilities. The main advantage is that matched with co2 and optimal nutrition, the plants metabolism will increase dramatically. I have only successfully tested this photoperiod for two weeks. The potential for a net increase of 40% over the entire cycle (80% increase in light energy vs. 40% longer wait) is worthwhile. Don't be afraid!

Day 1 - Sunday, 6:00am til Monday, 3:36am
Day 2 - Monday, 3:36pm til Tuesday, 1:12pm
Day 3 - Wednesday, 1:12am til Wednesday, 10:48pm
Day 4 - Thursday, 10:48am til Friday 8:24am
Day 5 - Friday, 8:24pm til Saturday 6:00pm

Click to expand...

Yeah... misunderstanding.


Dubs

Sauron, thanks for the info and help.

Tried and tested!

Tried and tested!

Easy Soxx. And good day to you sir.

I had experience with an extended light period.

Went something like this.
After 3 weeks/21 days - Add half a hour, every 3 days.

By week 5 of flowering (day 32) i was on 13 1/2, off 10 1/2.

Day 36 14-10

Day 40 15-9. Until day 50ish.

Day 52 14-10.

Day 54 13-11.

Day 56 12-12.

Harvest day 63.

That was 3 years ago. And ain't bothered since. But it did seem like a big crop. But had nothing to grow as the same to compare.

Might try it on this grow. As it's a second run of the same mother clones, that i'v just grown 12/12 all through flowering.

I would encourage people to read up on the Krebs cycle. We can rassle on the innerweb if ya like tho. bitch.

seesawsee said:

I would encourage people to read up on the Krebs cycle. We can rassle on the innerweb if ya like tho. bitch.

Click to expand...

please elaborate all knowing seesawsee.

dude....
your a stoner!!!
thats not what the mag says atall!!!
infact im reading it now....
its a 18 hours day (6day+12night) not a 30 hour day (18d+12n) like your sugesting...the whole point is for a 4week period to lapse in 3 weeks.
its only been shown to minorly impact yield.. combined with a 12/12mix say a fe3w weeks of 6/12 then the rest in 12/12 u could shave a week off each crop, without yield impacted.

thats my paraphrasing not copied.
18/12 might actualy promote bigger plants... i had a few instances in a single crop where i left the lights on (accidently) for 36 hours and then 12 night.. and they grew by noticable amounts in that short 36h window.

Ha Ha



Dubs

6/6/6/6=24

6/6/6/6=24

Dubbydubdubs said:

They believe the plant absorbs all its energy within the first 6 hours of light and the rest is a waste.

Click to expand...

ok this popped into my head last night before i had even read this thread
I'm gonna try next run
ok here it is.....
the veg stage: 6 on; 6 off; 6 on; 6 off
thats 12 on 12 off per day
has anyone here tried it or will i be the first????

Yeah ogenko, people have tried it. They stay vegging, and it saves power. Some people do this for mother plants that they don't want to grow as fast...