GLR vs 16/8-18/6 Light Schedule!

Ok im pointing out the difference with light schedules. Major difference in growth. These are the same strains under the same lighting and conditions. Same nutes. I just wanted to point this out because everyone says GLR sucks and its not worth the time. Its not the point of it speeding up the veg process, its the fact that it will get you a much bushier plant in a whole and it saves electricity. Both lighting grow the plant at the same speed. GLR is just great because you can cut down on electricity and run other equipment if necessary or more grows for that matter. Its also for growers who are scared or nervous to go with a 1000w lamp because of the high wattage. Make a 1000w usage look like a 600w usage on your bill. etc.

And this is done with NO training (LST, super crop, pinching, topping, FIM). I let them grow with out disturbing there veg.

PS. GLR wouldnt be great for sativa dominate plants. Since they grow thin and tall. IMO I think sativas would be great for SOG for sure. Thats what im doing with my Cheese Wiz Qush. (Check out my FIRST JOURNAL. Still in progress)

GLR Light Schedule. Notice how the side branches grow out all the way up the main stock. Which is only left with about 4 nodes thats tight and close to the main stock. GLR focuses on the whole plant instead of lateral growth. This is good for SCROG or if you just want a bushy plant(s).

16/8-18/6 Light Schedule. This lighting only focuses on lateral growth. The side branches will not grow as well but if height isnt a issue then it is perfect. Notice how theres about 7 nodes of tightness around the main stalk. This lighting is perfect for SOG grows.
lovely plants.

have no idea what GLR is, though.

Green Lantern routine.

It basically means in a 24 hour day your lighting will be like this.

12 hours on, 5.5 hours off, 1 hour on, 5.5 hours off

btw ผมรักเมืองไทย
I totally agree with you there wiz! GLR really helped my plants out a ton and saved on the electricity build! I got a big article on it if anyone want it just inbox me!
ah. the first description had me thinking there would be no way for my humble electro-mechanical timer to accomplish this, but seeing this chart, I think it could work.

I would like to know more about this lighting style.

it doesn't say what type of lighting is recommended and it seems to me that the firing up of my HPS is more energy INefficient than the running of the lamp(s) so that starting them up multiple times a day is going to drive up my electric bill.

however, if I'm just running my CFL's, no big deal.

I guess I've been following old school rules: 18/6 until flowering, then 12/12.
Thai man, that type of thinking it really is more of a old wives tale. Like leaving a light on is better then turning one on and off, its just not true.

I looked into that for house lights, and while yes turning on a light does use significantly more electricity for that one second then if it was running, it comes out to anywhere from 10 seconds worth of running electricity up to about 1 minute for big ballast using lights.

So while turning a light on and off over and over could burn a lot of electricity comparatively. In reality with a GLR we are only talking about turning on a light 1 more time per day. Basically with a GLR lighting you are looking at paying for about 13 hours 2 minutes worth of electricity a day, while a 18/6 lighting would cost your 18 hours 1 minute of electricity per day.

You will still save about 5 hours worth of electricity.

If you need a better timer they are only 5-10 bucks at the store.
Well put Jimmy. Also you don't have to set your HPS to turn on for that 1hr. You can simply just turn on 1 CFL light. So set your HPS to 12/12 & set a CFL for that 1hr to turn on.

How GLR works it builds up the hormones in the plant like its about to flower & then when the hour of light disrupts the night period it destroys the build up of horamones. So it keeps it in veg. This in turn is great for quick sex recognition with out waiting to go 12/12. Also your plants mature alot faster which triggers faster flowering when switched to 12/12. I don't run 12/12 though I find that 10/14 works alot better.
Yeah just make sure the CFL is fairly close to all plants. I had some weird flowering reveg stuff happening that i believe might have been due to my T5 being too far away.

I can't say for certain but i really cant imagine what else would have caused it as my lights were on 24/7 and I had some plants go into flower then reveg, in the same tent as other plants that just kept on growing in veg. If its not that I can not think of what else it could be.
Hey Wiz I was looking around reading your journal in progress and seen you dedicated a thread to GLR. I caught on to that a couple months ago from you when you shot a comment my way and I learned of it, It sounded good and I reset the veg timer to it from 16/8. Was scared at first and only did 12 on 5 off 2 on and 5 off again under my T5. I still use those hours and going into my first flower from it in my current grow only after like 2 weeks of GLR it had already built those hormones and seemed to flower faster. Im still running clones of clones of 2 bag strains so it was a noticeably faster pistil popping to me. I also saw found this on GLR later and thought it reinforced the pros to me after I already started it thanks to you .
I hope its not too much to put up on someones thread and it origanlly came frm ? but I found it posted here at 420
and I hope it can contribute

Re: my low budget medical grow
This was nice info on GLR. My first exp going from it to flower now

10-17-2012, 07:40 PM #82
420 Member
post #82 on this completed journal

something i found over at UK420:

The Gas Lantern Routine

This information will seem quite revolutionary to growers who have been using the standard cycles to produce cannabis, seemingly with little or no trouble at all. Actually, in a grow that more closely mimics the outdoor growing environment under indoor lighting conditions, the plants may be maintained in vegetative cycle using only a total of 13 hours of light daily, which dramatically reduces the cost of production.

The less is more approach of the Gas Lantern Routine provides the growing plant with adequate darkness to promote health, and by inserting a full hour of light in the center of the dark period, the plants are tricked, and neither flower nor express hermaphrodites. The growing plants get more than the average amount of rest, thus reducing stress, and improving plant yield, overall performance, and medicinal quality.

Seedlings and Cuttings

The Gas Lantern Routine is applicable in seedling phases of plant growth. As stated before, nowhere in nature does the springtime ever provide an 18-hour photosynthesis length; rather, the growing spring light may in fact be 12 hours or less. Lighting for seedlings and cuttings needs to be bright, but compact fluorescent or T5 lighting may be used while in the seedling phase. Rooted mature cuttings can immediately light with HID lighting.

The Vegetative Schedule

This method is quite simple: 12 hours of light, followed by five and one half hours of darkness, a single hour of light exactly, and then a second period of five and one half hours of darkness. Placing a full hour of light in the very center of a 12-hour dark period tricks the plant and interrupts the buildup up of sensitive floral hormones, which would normally trigger flowering by destroying them. The grower simply raises the plants to the desired size before switching to the fall schedule to bloom.

Using this method, vegetative duration may be also reduced, and with a shorter growth cycle comes more frequent and better production. Vegetative cycles can be shortened by one to two weeks, and flowering may also be shortened a week or more using this method in con- junction with a diminishing light schedule.

For patients growing their own medicine or for compassionate cannabis providers, production turnover may be increased from four to five crops per year or more using rotation, and power consumption can be reduced even further by the use of high-intensity fluorescent lighting during vegetation, and overall, power consumption savings can be 50 percent or more.

The Flowering Schedule

Plants that have been grown up using the Gas Lantern Routine are now supercharged with floral hormones, and ready to go into flower with the slightest provocation. The interruption of the dark period has been destroying enough of the naturally building hormones to keep the plant from expressing sex, and the well-rested plant now has plenty of stored nutrients and energy to finish its life cycle and flower. Triggering the plants is essentially just a matter of removing the interrupting light period, so the plants may now experience the full buildup of hormones that will trigger blooming.

In keeping with providing all the correct organic biological and environmental needs of the plant, the diminishing fall schedule should be employed to take full advantage of the hormonal preparation created by using the Gas Lantern Routine. The diminishing hours of light in nature trigger acceleration in the production of hormones in the plant, making it flower with increasing speed and power.

The Diminishing Lighting Schedule

The diminishing fall schedule begins with an evenly halved light schedule, using 12 hours for the first two weeks to trigger the plant into bloom, and then further reducing the lighting for increasing darkness time by one half hour every week.

The final week of flowering will provide the plants with a mere nine hours of light, with 15 hours of darkness, forcing a resulting final explosive hormonal buildup. This sends the plant into blooming overdrive and produces resin far beyond the normal plant's limits.
When the Gas Lantern Routine and Diminishing Light Schedule are used together, they create healthier, more naturally robust plants. These important and historical botanical techniques are soon going to become very important techniques in the coming years as medicinal cannabis research continues to advance. When viewed from cost of production, organics, and medicinal needs, the methods currently being promoted can be seen counter to the interests of growing healthy plants. Understanding your plants is the best way to grow the best medicine, and looking for solutions to growing problems by observing nature always provides the right answers.


Saves electricity (11hrs of saving from 24/0, 5hrs of saving from 18/6)
Promote healthy plants. Any deficiency it has the plant will be able to bounce back with new growth after adjustment is made
Promote plants growth, 2x more than 18/6, and 3-4x more from 24/0
Cuttings will root much faster with thicker roots and more hairs
Clones under bloom (12/12) will induce flowering much sooner
Less on hours = less heat = stealth


Must have good ventilation if the tent is closed or the tent has to be left open for the 1hr on between the dark cycle.
Must have good odor control. Healthy plants produce more aroma even in veg.
Plants in small container may get root bound due to rapid growth

Some tips using GLR (theory):

Have the light on a timer so the on/off is consistent daily. Manual on/off may induce flowering.
Use mix light or MH. Try not to use just HPS. The spectrum from HPS may induce flowering even with the 1 hour on between the dark cycle.
For the 1 hour on use a cheap light source like Fluorescent light or CFL instead of using HID light. Have it on a separate timer only turn on 1hr between the dark cycle and have the HID light set at 12/12. Normally with any other light cycle the ballast is turned on once in 24hrs, with GLR it turned on twice. This may shorten the lifespan of the ballast and bulb. If you decided to run Fluo/CFL then make sure the tent is well lid any shaded area or area left in the dark may induce flowering. The 1 hour on between dark cycle help destroy floral hormone, lack of light will not be able to destroy the hormone and will send your plants in bloom.
Thanks Closetorganic for sharing more knowledge about GLR. And im happy that its working for you. You say 2 hours on during the dark period? That sound interesting. And surprisingly enough you stated that it works out well. Cool! More proof that alot of things work. Just need someone to try it out for proof and comfort. Im giving you reps for that bud! :thumbs.

And any information or pictures you can share them here on this thread. Its no problem thats what I made this thread for. So everyone can share there GLR experiences! :)
I'm psyched; however, I'm finishing week 6 of flowering, so a bit late to start this now.

but I can easily reduce the light period. are you recommending it?

(BTW, I'm Farang, NOT Thai man.)
I'm psyched; however, I'm finishing week 6 of flowering, so a bit late to start this now.

but I can easily reduce the light period. are you recommending it?

(BTW, I'm Farang, NOT Thai man.)

Yea some growers during the week 6 of flowering will start to diminish the light period to around 10. It will really build calx's and also get more trichomes on the buds. It also will plump the buds up. Im running 10/14! So you can switch your light straight to 10/14 or take a hour off every week. I would go straight to 10/14 :)
wow. you're up late. or early.

I'm about to drop the light to 10 right now.


I guess its both late and early depending on how you look at the time lol. And no problem. Keep your plants healthy and you will see remarkable results. Even though lighting is number 1. Health definitely plays a huge roll. :thumb:

Here are some of my plants now just in 2nd week of flower. Running on 10/14

as of right now, I'd be embarrassed to show my grow.

about 10 days ago, I decided to put a second 400w HPS onto the grow at 12/12. this was not a good idea.

today I swapped one out for two 250w CFL's plus the single HPS and now will adjust the timer for a mere 10 hours of light.

I agree that keeping the plants healthy is a major piece of the puzzle. I spend a lot of time reading organic farming sites and their supposition would make a whole lot of heads explode on this and other like-minded forums. it's this: predatory pests only attack UNhealthy plants.

my plants have fallen in that category as I have a white fly infestation, the first pests I've seen.
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