Photoperiod: Veg @ 18/6, 20/4 or 24/0

I'm unsure if this kind of query has been raised before. If it has forgive me for repetition and I'll be happy to follow any links to existing threads.

I'm vegging under 1 600W HPS for 18 on 6 off. Does any one know the science behind 18/6 as oppose to 20/4 or 24/0? Please Share!!

I've read on other sites threads that offer differing opinions. Some people swear by 24/0 while I have never tried any other regime besides 18/6 unless it was by accident where timers didn't switch off the lights for over a week. What do the experienced farmers of Cannabis.com reckon?

I'm thinking of taking cannabis cultivation to another level and studying for some kind of botanical accreditation..

16-24 hours of light is all that is needed for vegetative growth cycle. You can put it on 24 hour light but it will cost more energy to run the light 24/7. Most people do 18/6 to save on energy.

there is a thread on here that shows that 18/6 grows roots better than 24hrs

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Originally Posted by Paht_Hed

16-24 hours of light is all that is needed for vegetative growth cycle. You can put it on 24 hour light but it will cost more energy to run the light 24/7. Most people do 18/6 to save on energy.

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It surely cannot be just the financial/energy saving aspect?

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Originally Posted by gt420z

there is a thread on here that shows that 18/6 grows roots better than 24hrs

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Thanks, I shall search around. The opinions that I sourced from elsewhere mention the same theory with regard to root formation. Still wondering I anyone else has experience of comparrisons...

I think you'll find "hard evidence" difficult to come by. It's my belief that most ideas that may show a worthwhile gain in yield are the ones that get documented. But since there is no "easily" discernible difference found between veg. light schedules, no one has bothered to do a real scientific research study. Most folks just go by the accepted guidelines and concentrate on maximizing other variables that make a larger difference over the course of the grow.
So, I also believe the choice is based more on energy savings than on raw results obtained by that choice.

Most people grow with MH/HPS who use a 18/6 schedule b/c they are so damn expensive to run if you have say 2 1000 watt setups. I run 10 cfl bulbs and keep mine on 24 hr light.

During the propagation stage, lights should be left on as long as possible, up to 24 hours per day. Strong initial growth will make the young plants healthier and more resistant to disease, ultimately providing better yields. As the plants begin to mature, however, light duration should be reduced.
Plants use periods of darkness, too. During dark periods, plants continue to take in oxygen and give off carbon dioxide in a process called respiration. During this time, the plant uses some of the energy that was stored as sugars during photosynthesis, producing proteins, hormones and other complex products. Therefore, lighting mature plants more than seventeen and a half hours per day will not increase production significantly, since photosynthesis will slow down after a certain number of hours. I have been using this method or years and see great results. 18\6 is a easy number to remember.

Good info there growbe. And might I say, Welcome to Cannacom!

Thanks for all of your replies.

With this information I am deciding to run my veg roomusing both 18/6 and 24/0.

I will veg my mothers with 18/6 most of the time. But when I fill the propagator with cuttings from the mothers I will run the lights @ 24/0 until the cuttings are rooted. Then once I see signs of all cuttings showing roots I shall revert back to 18/6.

I want strength and good root formation, so I will utilise both methods.

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Originally Posted by growbe

During the propagation stage, lights should be left on as long as possible, up to 24 hours per day. Strong initial growth will make the young plants healthier and more resistant to disease, ultimately providing better yields. As the plants begin to mature, however, light duration should be reduced.
Plants use periods of darkness, too. During dark periods, plants continue to take in oxygen and give off carbon dioxide in a process called respiration.

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I agree 100% except for the last sentence. (bold text) lol Think about that for a second...

This is one of the best aspects of indoor cultivation. You can control many aspects that mother nature doesn't bother with.

Bottom line with almost ANY plant is during propagation the more light the plant receives the faster it breathes (grows). Because of this, a good source of CO2 is absolutely REQUIRED for propagation under 24hrs of light. This creates a chain affect wherein good soil is also needed too.

I don't recommend 24hrs of light unless all other conditions are completely ideal...

I believe it HAS been proven that the light reduction over a period of time yields a healthier plant overall. I don't think it changes the actual AMOUNT of the yield but I do believe it has a HUGE affect on the quality and potency of the plant.

Always remember though, 12/12 is the MINIMUM required for growth. Never ever go below that. At least from my experience.

From photoperiod to Mothers & Clones

Just to side step the photoperiod issue... I have set up a small veg garden adjacent to the bloom garden. I put a 125W Envirolite in there with an adequate extractor. Both pieces of equipment are running all the time. In to the room I put 3 slow developing clones in 15L pots and 6 fresh cuttings from my G13 plants in a propagator. The clones were very wilted on the day I put them in the propagator.

They were initially on 18/6 with all the other plants in the bloom room. Since dropping the lights in the bloom room to 12/12 I've put everything I want to veg under the 125W Envirolite. Within 36 hours I am seeing more development with the slow takers and the clones are upright in the propagator.

This shows me that 24hours of light must be useful to some degree. Also, the correct spectrum of light for the right phase.

The G13 have grown rapidly in veg under one 600W HPS for the 16 or so days they were vegging for. While the other strain was really slow. I'm confusing myself a bit now, so I'm going to hit my joint a few times then finish up....
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OK! I think some strains that are quite resilient in the genetic characteristics will thrive under numerous variable conditions; including 18/6, 20/4, and 24/0 veg regime. I have vegged G13 and femenised PPP for 24hours in the past and growth was alarming when the lights were turned down. I did wonder if vertical growth would ever cease!

I think other strains, usually recommended by seed companies for experienced growers, need a more refined environment.

Can any experienced growers shed some light on the aspect of Genetics Vs Photoperiod?

It would be interesting if dependency on genetics is a contributing factor to how one should adjust their gardens environment. Example: If I grow a strain indigenous to an equatorial region, should I adjust my garden environment to replicate important aspects of the climate in that geographic location to maximize my yield? As a guess, a plant in its originating environment should yield maximum beneficial produce comparative to a more northern or southern hemisphere climate put in its place....

Thank you ladies and gentlemen!!

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Originally Posted by home.grower

It would be interesting if dependency on genetics is a contributing factor to how one should adjust their gardens environment. Example: If I grow a strain indigenous to an equatorial region, should I adjust my garden environment to replicate important aspects of the climate in that geographic location to maximize my yield? As a guess, a plant in its originating environment should yield maximum beneficial produce comparative to a more northern or southern hemisphere climate put in its place....

Thank you ladies and gentlemen!!

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Me being a native outdoor cultivator I believe I can expand a bit on this. I'm no genius but I'm pretty knowledgable about climate changes and what not...

Short answer to your question is yes, absolutely.

There's a certain level of common sense and overall natural instinct on climate variation that goes hand in hand for everything from plants to animals comming from different regions. Example, if you buy a Monitor lizard from a pet store, you don't throw it into a dry fridged environment and expect it to thrive. It would die rather quick...

If you're given specific specifications on a particular strain native to a particular region it would be optimal and complimentary to grow under its native conditions. This would include the regions photoperiod.

Equitorial strains would require completely different accomodations than a strain native to a more seasonal region. For one, the seasonal changes in light abundance are not as extreme in equitorial regions. Thus, you would want to gather the regions photoperiod information and apply it to your grow accordingly. The more accurately you can mimmic the regions climate the more "at home" the plant would feel and therefor the healthier it would develope...

Does this mean that it is absolutely REQUIRED that you accomodate the EXACT conditions of the native region? In my opinion, no. I'm sure the plant would semi-adapt to survive. Animals may not. Plants have that ability. But only to a certain extent.

Plants being different from animals in that they require 3 basic things (light, soil and water) to at LEAST survive you can rest assured that if you are attempting a grow with a tropically native strain your plant will not instantly wilt and die if your humidity level falls below 70% for instance..lol.

Does accomodating the right conditions mean higher yields? Maybe...Probably, given all the other elements in the grow are up to par with the strains native region. (soil, temperature, humidity, ect.)

Remember that the climate is not always EXACTLY the same every year in any given region. Climate changes can be very little to extreme in some cases. Plants tend to adapt accordingly in the region. Some species may not...

I always say try not to apply too much knowledge to your grow because the basic rules of life still apply, you just never know!

Hope I was of some help...

That was a great help EXP13.

But some factors, like humidity, if controlled can produce better results. Hmmm. ~I think you are right in the sense that I may be trying to over complicate the grow process. I'll stick to the basics.. but after a few hits on some good herb these questions just keep poppin in to my head.

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Originally Posted by home.grower

but after a few hits on some good herb these questions just keep poppin in to my head.

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:D They always do.

I'm the same way man. Once I start smokin' my brain starts churning up all kinds of ways to induce heavier buds and bushier plants...

The biggest problem I've seen with indoor growing and altering the environment is that sometimes people don't always offer compensation for thier changes.

For instance, if you put a seedling on a 24hr light cycle it starts eating up that light very fast. What happens with this is kind of a domino affect. The increase in the light/time ratio will cause a need for more C02, more water, and more abundant nutrients in the soil. This is inevitable when you screw with the photoperiod.

In most cases when you change one thing it can offset something else and sometimes you never know what the results will be, depending on what's changed of course...

Because of this it makes it VERY useful to know what strain your plant is and what the climate is like in that region. Knowing that will allow you to mimmic its natural climate more accurately and maintain a more stable environment based on the climatic changes of that specific area.

So I guess knowledge about your seeds origin is key here for the healthiest yields. No doubt about that!

:smokin:

wow so much information am i at cannabis.com?

this thread is/was very educational CC usually has a bunch of drunk-as*es saying "ur wrong" ty

i grow a breed of C. indica designed for outdoor cultivation around my area witch makes the pot easy to grow but also BB bud turns purple with root temp reaches 45df

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Originally Posted by BlackBerry

wow so much information am i at cannabis.com?

this thread is/was very educational CC usually has a bunch of drunk-as*es saying "ur wrong" ty

i grow a breed of C. indica designed for outdoor cultivation around my area witch makes the pot easy to grow but also BB bud turns purple with root temp reaches 45df

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You've proven to be a waste of space around here.........have fun at other sites and WELCOME to Club Gitmo for CC Abusers.:thumbsup:

Have a good grow!:jointsmile:

Ok then... I'm stoned once again, puffin on some good erb to ease my mind and heighten my meditation...

With this supposed climate change, and knowing that plants have tolerances to their climate, how possible would it be to some how force a species of plant to cope with a new climate permanently.

Ok, cannabis grows once then dies, but would it be possible to exploit a plant and make it produce seed; plant the seed and hope that eventually there will be a bunch of seed that have the right characteristics to grow outdoors where it otherwise wouldn't...? Do you see the query?

I look at my plants and would love to get them to develop the same, if not better, out in the wilderness of the northern hemisphere. I'm not looking for suggestions on changing strains as oppose to seeing a strain that could well survive all climates and flower in 30 days under all circumstances

What you're lookin for would be climatic adaptation.

This would take generations (shorter with clones) of the same strain to achieve.

With some strains it may not even be possible.

Who knows...

Just to get back on topic i am growing 2 white widow plants.Its a very basic set up.A cupboard with 3x20watt CFLs(100watt equiv)

At the moment they are 6 days old.I have them on a 18/6 light cycle..Could i switch over to a 24hour light cycle? and would it do any damage.

I will flower using 2x20watt CFls and 2x125watt envirolites.

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Originally Posted by privatepile

Just to get back on topic i am growing 2 white widow plants.Its a very basic set up.A cupboard with 3x20watt CFLs(100watt equiv)

At the moment they are 6 days old.I have them on a 18/6 light cycle..Could i switch over to a 24hour light cycle? and would it do any damage.

I will flower using 2x20watt CFls and 2x125watt envirolites.

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No, it wouldn't do any "damage" so to speak.

What it WILL do however, is cause your environment to require more CO2, more abundant water in the soil and better nutrients in the soil.

Now will your plant die if you cannot compensate? Short answer is no.

Long answer is it would be completely pointless to switch to a 24hr light cycle if you're not going to utilize the extra light. The more light you have the faster the plant will want to grow. To utilize this properly you have to compensate.

Now given the fact that you're operating on a low wattage light setup you may not have to compensate at all for the extra light.

All in all longer light periods are generally beneficial for fuller growth. Just keep an eye on your basic elements and adjust accordingly. Usually the biggest thing is CO2 and water. If your plant/s start wilting, turning color, drooping or showing signs of stress in any way after changing the light cycle try adding water as your first resort. (check the soil of course)

If water isn't the issue then CO2 is your next bet. Chances are the extra light is actually choking your plant. Being in such a small area with unnatural air-flow and abnormal levels of CO2 this is a serious issue and is over looked a lot by new growers.

Goodluck with the 24hr cycle.

PS- I personally don't reccommend it.

Thanks for the help.I am going to stick with the 18/6 light cycle.Let nature take its course.

Plants have to sleep else well i suppose

I took some cuttings from a few plants and had them spend one night with 18/6 then the last 9 days with 24/0.

When the cuttings went in the new space they were quite wilted. Within 24hours of continuous light they were very erect. Also in the room are 3 potted clones that are now entering day 25/26 of veg since acquired. All plants show good signs of life having been under 24/0 for some 9 days.

Yesterday I thought I had achieved my week long propagation period of 24/0, so I added a timer inline with the light and commenced 18/6. One of the cubes has started to show numerous thick roots emerging from the cube. All the cuttings are showing good signs of health, but not all are showing their roots.

I've never delved into taking cuttings from my own mothers until now, so this is much to do with experimentation that perfection of current methods. I think 9 days is quite long for rooting time...

I will take some more cuttings once these ones are rooted and see if 48/0 then 18/6 give the cuttings such an abundance of energy that I can get my cuttings rooted in less that the present time its taking.

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Originally Posted by EXP13

What you're lookin for would be climatic adaptation.

This would take generations (shorter with clones) of the same strain to achieve.

With some strains it may not even be possible.

Who knows...

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strains that might carry certain genetic traits of the Low Rider strain, which flowers as soon as it starts growing could be used to speed up the process of climatic adaptation?

Speeding up the growth process primarily to harness any genetic attributes that manifest total climatic resilience would be cool. Then once its harnessed it could then be crossed back in to well known strains. then maybe all strains could potentially loose their climate related growth characteristics/association.

Too much Big Bud in mi spliff mi thinks....