Pros and Cons of 24/0 VS 18/6

Hey All!

Whats the pros and cons of using 24/0 lighting vs 18/6 -- i've seen both posted as the "proper" way for vegging, but no definitive answer. Thanks!

I think the reason no-one has answered your thread, is because there isn't any definitive information on this. If anyone answered this with a tone of sureness it wouldn't mean anything because there's no real proof to back it up.

Honestly all I know is that 18/6 is more forgiving on your electric bill. I personally haven't seen much, if any, increase in growth from 24/0 so I keep my stuff on 18/6 just to save 25% on the electricity.

High!

Ekras san,18/6 is better because its more natural. But 24/0 is better because it keeps the plants more squat due to a lack of darkness.

When the lights are on, the plant uses photosynthesis to grow leaves and some stem. But when the lights go off, it no longer has a source of light energy, so it uses the energy it has stored to grow upwards so that it can once again reach the light.

But plants tend to look a little bit less healthy with 24/0. The leaves tend to somewhat flop over.

When the plants are given that 6 hours of rest, they tend to perk up and look much more healthy, with leaves pointed upwards at a 45 degree angle.

Basically, there isn't much of a difference, it's all about what you perfer.


Good luck, grasshopper.


~Ninja~

Difference is 25% more light per day and the growth that comes with it. If you need growth faster--24/0 is the way to go. If you're maintaining veg 18/6 is adequate.


I've heard of breaking up the night into 4 --- one to two hour darkness periods can help prevent autoflowering, etc...

I've done it a few times, but backed off b/c i didn't want too much wear and tear on the ballast/bulbs

hmm, possibly have it on 24/0 for lst to hurry it up then give it alil break with 18/6 to recuperate before going to 12/12?

Hi,
Some strains of sativa will start to show preflowers without 24 hours of light.
which is bothersome, slows down the veg process.

a four hour - 6 hour dark period is beneficial to your plants in turns of ultimately yield and quality. i don't have the tech to experiment in as much detail as oldtimer but my plants definately like some down time. who doesn't?

ot1 said:

We did a lot of experiments with light times a few years back using known sat and sat dom clone lines.

With Vegging ie under hid lights.

20/4 produced the most sturdy growth and the most bulk. Best final yield, taken as 100%.
22/2 Less of both. yield 88%
18/6 Studier than 22/2 but slightly less bulk. yield 87%
24/0 Much lighter in all aspects than 18/6. Yield 79%
16/8 The weediest plants. yield 67%

Plants vegged to final pots under fluorescents at 20w per sq ft on 18/6 yield 49%

For the mum lines we have 20/4 to 12/12 gives the best crop weight and bud quality, really thats all I’m interested in.

Click to expand...

24/7 or 20/4.

There is no definitive answer. Everyone has their own way of doing things.

My 1st indoor grow i started with a 400hps on 18/6 from clones, i messed up and wana switch to a MH bulb, would that mess the plants up? I think im goin to start a bio bucket grow very shortly once i figure out the cost of materials.
my aim/yahoo sn is plumpm0nkey

I find that running longer than 18/6, specifically 24/0, that when you place clones/veg plants into 12/12 that they seem to know it's time to flower that much faster...

I think 18/6 is used for a couple thiings..
first if you grow outside.. and DON"T want your plants to flower right away.. but want them to veg into big trees.. its beneficial to have your mothers and everything running 18/6.. one being some strains will just start flowering if you drop the light hrs quickly... once its done... you might as well kill the clone and start again.
If a mother can handle 18/6 it helps a gardener tell if its stable although actually keeping the cut and using it is the only thing that will prove it. If you don't care about growing larger vegged trees outside.. most inside gardeners don't test it/do it.

second.. I've read that 18/6 promotes root development more than 24 hrs. Not saying that 18/6 will grow faster than 24 hrs.. but.. in hydro it probably matters less.. but in dirt vegging longer at 18/6 is supposed to help.
I'm giving full disclosure.. I don't know if this is proven fact.

Third.. like was said 18/6 would save a little on elec...

so the only reason to veg 24 hrs.. would be because you want to shave a little time off veg or your prize momma starts autoflowering and you have to keep it 24hrs.

edit: any plant that starts to flower at 18/6 should be cul'd from breeding so as a rule lots of breeders try to use/mimick the outdoors indoors too.

Cannabis is a C3 plant. Means it doesn't need a dark period.

18/6 will save you 25% electricity, and slow your growth down by 25%.

Anthropomorphism is a common thing and tends to get in the way of growing. Just because humans need sleep, doesn't mean cannabis does.

Ed Rosenthal wrote a lot about light cycles. You can find a lot of his old "ask ed" columns over at cannabis culture.

Gorilla grower has got it right on the dot! I have found from personal experience that 24-0 is really good to grow sturdy fast growing bushy small plants. But, if you are a guerilla grower or outdoor in general you have got to set you timing on 18-6 becasue once you bring those 24-0 plants outside to veg longer they might just start flowering right away...I go with 18-6 for indoor to outdoor growing, and 24-0 for indoor to indoor growing.

As far as I know cannabis requires no dark periods during vegetative stage. Introducing dark periods provide no benefits to the plant, slows growthrate and increases internodal spacing. And yes it belongs to C3 photosynthesis group. There is no better light cycle to cannabis then 24/0 for vegetative period.

well I guess what is being said for 18/6 and everything besides 24/0 lilo.. is there is reasons for growers to choose their system.. Indoors growing.. where the headspace needs to be kept to a min. where people are all concerned about plant numbers.. And like I said with Hydro.. Indoor growers(especially the majority of hobbyists) in general don't need a long veg time and worry about root zone growth.

No one is saying that Cannabis needs a dark period to sleep or get some rest.. .. to kinda clarify what I'm saying..

The dark period that cannabis experiences creates changes in the plant... let's see kinda like puberty.. things change.. hormones do different things..make different plants react and grow different.

LIke what was trying to be shown above 20/4 seemed to work best for a particular online member with his cut in his room. You can see how in his system w/ his plant size etc. the difference in growth.. because the plants are in different stages.

Many things affect change.. temp in room , temp between night day , dark hrs , condition of soil,, list goes on.. it all creates changes in hormones and the like.

The small book by DJ short has some interesting stuff in it.. albeit quick and small ..

He explains that using 18/6 -> 12/12 on pure indica plants is not the best way of coaxing the sativa or in his ideals better quality expressions out of the plants.
He recommends with each cut to experiment with the veg time in 30 min increments before move to 12/12 even in indoor. edit: especially with indoor


now.. unless you got some strain from alaska or antarctica that grows outdoor.. a 24/0 veg time would be unnatural.. and its obvious from what everyone says.. the leaves grow weirdly large and crinkled sometimes, the internode spacing can get shorter aren't normal natural expressions from your ganja. For whatever reasons different gardens may benefit from those unnatural expressions.


I am not saying that 24/0 doesn't work or isn't beneficial.. I'm just trying to give info. And yes in a way 24/0 can be beneficial to sativas and sativa crosses the majority of plants and strains grown. The reason being is the plant flips quicker and has a less gradual change.. but some people believe that stuff is getting missed in that quick change.

The nutrients from this company are kinda interesting.. does anyone know much about them? http://www.lifecircle.com/ if you read the custom lines pdf.. it explains at the bottom that each season has a different mix.. and if you use the autumn to soon there nutrients will affect cell elongation and division.. and you wont get the best yield. It's kinda interesting. ..but along the same lines of expression through enviromental control. I wonder if other company's are using the same techniques.. I'm sure to some degree right?

I found this on another site, sounds pretty good to me.

" Light Cycles

The dark cycle is very inportant to palnts. Respiration (this is when plants are making energy from sugar to oxygen) Continues in dark but at a much slower pace, almost independent of available oxygen because the leaves are not making oxygen in the dark.

In the dark there is a shift from leaf production to root production as the leaves transfer excess energy down to the branches and roots. Therefore, some dark time allows for better root structures. The "Experimental Root Growth 10 Days After Cutting" graph on page 33 shows that giving plants a 24-hour light cycle is not the way to supercharge growth"



This is from "How to supercharge your garden" With the graph on page 33 this follows...

"Light period for cuttings

Plants have a free running internal bio-rhythm of 21-27 hours. In this rhythm, they need dark time. Cuttings have a built in daily rhythm (age also) that they inherit from their parent. Cuttings will root better with a 6 hours to 8 hourdark period because this is the main time when leaves and the stems transfer energy down to the root zone for storage and growth."



The chart has hours of light per day on the bottom, and length of roots in millimeters.
-@ 4hours of light the roots after ten days were only 22mm long
-@ 8 hours of light after 10 days the roots were 25 mm long
-@12 hours of light we shoot up to 40mm long
-@16 hours it peaks at 50mm
-@20 hours it drops down to 37mm
-@ 24 hours it drops down to 29mm

There is also a shitload of info regarding root to yeild ratio vs veg to yield ratio, and draws the conclusion that at the end of the experiments the root to yield ratio was higher

Revegged_Clone said:

hmm, possibly have it on 24/0 for lst to hurry it up then give it alil break with 18/6 to recuperate before going to 12/12?

Click to expand...

i did that semi recently, and used to do that regularly.

i started upping ppm's usually to get a base-high # for beginning flower, and nursed them in 18/6 while i did it. then i usually had them greened, and growing, and then hitting the 12/12 without those annoying 'nute-spikes' and light intros, that make those base braches stretch like 24" up to the side of the plant in 4 days. fuck that shit. so i found it helped with the squatness, when i was going for squatness.



being tied down, and manipulated alot though, i can't put my finger on one thing specifically, but whatever's clever.

Iluvtomatoes said:

Difference is 25% more light per day and the growth that comes with it. If you need growth faster--24/0 is the way to go. If you're maintaining veg 18/6 is adequate.


I've heard of breaking up the night into 4 --- one to two hour darkness periods can help prevent autoflowering, etc...

I've done it a few times, but backed off b/c i didn't want too much wear and tear on the ballast/bulbs

Click to expand...

I'm a serious newb, but doesn't it need the dark time to recooperate and promote growth?

I do agree they seem to stretch harder when goin direct from 24/0 to 12/12, but that helped with my SOG growing style. Better to have some nice stretch so you can get those nice single colas on a 2-3' plant from a 6-12" fresh rooted clone.

HOWEVER, I did find when placing cuttings under 12/12 to sex fresh seedplants, they seemed to root EVERY TIME/MUCH FASTER than when trying to root under 24/0...

GorillaGrower You give some very useful input there and I agree with you totally on individual needs, environment and even genetics factors. However, where your very thoughts and space they occupy live, there must live our choices and i believe photosynthesis should be the main and starting point of consideration. I think, and that's been my limited experience, that provided decent stability level have been reached on humidity, substrate main properties and nutrient availability most varieties benefit from constant light schedule during vegetative period. First comes light and it shall be the one I always turn to for the maximum performance, make it work to the limit by adjusting other environmental factors to it. I found myself thinking this way really improved my experience. I see great sense in DJ Shorts findings on day/night, lighting movement and other properties. I would say: stuck? look at your lighting and improve and you open the door for hole new level, for a whole new set of other improvements. I find thinking this way really helped me.

Sammet Good info there! I apologize I had no chance of checking out references on the reading you'd quoted. I don't see any mention of plant variety - was it cannabis? I have to say though, when I hear of any findings and complex experiments I see choices being made, approaches taken, differences and - thus imperfections and even flaws. Not to disregard any of it but you know still the best book you'll ever read is the one written by you.