Veg: 24/0 or 18/6?

[R.H.Goddard]

Which do you think is better and why?

 

I've been looking into it and basically all I can find is never ending debates which end up delving into some some partially scientific/ pseudo-scientific arguments with heavy doses of anthropomorphism (I.e. "Well put it this way. I need sleep, therefore, so do my plants!").

 

However when it comes to input from those clearly versed in plant biology etc. it seems that many lean towards the notion that marijuana doesn't actually seem to benefit from any more than a maximum of 18 hours of light per 24 hour period, despite what even veteran grower Ed Rosenthal may state. Then again there really seems to be a lot of allegations of misunderstanding and misinformation from both sides; e.g. while some say the whole idea of more light = more photosynthesis = more growth isn't as clear cut as it seems, neither is the notion that plants 'focus' more on oxygen uptake and excretion of waste gases during dark periods.

 

Have any of the veteran growers here actually tested the hypothesis that there is no noticeable difference in the rate of growth/quality/yield etc. of a plant past the 18/6 mark?

 

Anyone found any seemingly reliable scientific studies/evidence?

 

Any Professors in plant biology cruising OzStoners?

 

I'll try find some good material on the issue myself and post it up here.

 

I think this is pretty important issue seeing as one setting requires 25% more electricity than the other, so there's a possibility of a pretty substantial saving there.

Edited November 24, 2011 by R.H.Goddard

[dani]

hey R.H

 

i always find lou lou gives best explanation for this, dunno if she's a professor though , cos she makes sense .. and is also speaking from experience

i hooked this out of another thread about 24/7- 18/6..

 

hope you don't mind lou lou ..

 

'' This is the bit that is in error, it assumes that growth only occurs in the presence of photosynthesis. During lighted periods a plant produces, uses and stores sugars. During 'lights off' the stored sugars are used to produce growth via light independent reactions.

 

I'm not suggesting that cannabis plants need a 'rest', just that growth continues after lights out''

 

''I just wanted to clear up the misinformation on plant growth and metabolism. The most notable difference I have found, personally, using different lighting regimes is that 24/0 uses 25% more electricity than 18/6... the plants turn out much the same regardless.'' .

 

 

 

 

search engine is always your friend too

 

[iTiC]

The need for a dark cycle ..

http://www.ncbi.nlm.nih.gov/pmc/articles/PMC34891/

http://www.plantcell.org/content/15/5/1212.short

[The Claw]

Welcome RH, have you looked at the 12-1 light schedule it's big on the rest period (11hrs) for growth, saves on electricity and theres less heat, less stress on the plants. I have been using 12-1 with no negatives. Anyone that has tried it likes it, but theres plenty of skeptics. I have some diaries here on 12-1 grows, 12-1 is: 12hrs on. 5.5hrs off. 1hr on. 5.5hrs off, then repeat.

 

 

These 2 have only ever had 12-1 from seed, they are a new cross between Tahoe OG Kush & Pineapple Chunk. I thought one was a male, but looks like their both girls

Vrod.

[STONEDAJ69]

Welcome RH, have you looked at the 12-1 light schedule it's big on the rest period (11hrs) for growth, saves on electricity and theres less heat, less stress on the plants. I have been using 12-1 with no negatives. Anyone that has tried it likes it, but theres plenty of skeptics. I have some diaries here on 12-1 grows, 12-1 is: 12hrs on. 5.5hrs off. 1hr on. 5.5hrs off, then repeat.

 

 

These 2 have only ever had 12-1 from seed, they are a new cross between Tahoe OG Kush & Pineapple Chunk. I thought one was a male, but looks like their both girls

Vrod.

 

Don't bother with Vrod and his silly theories, RH. Stick with 18/6, 20/4 or 24/0.

 

Plenty of reasons to go with 24/0 but it's just a matter of whether or not you can really afford the larger power Bill.

[El Gato]

I have done both and an see no difference. Having a good light is what makes the biggest difference.

[uncle chron]

24/7 is good to help reveg a plant that has been in bloom....and it also saves the stress of the timer dying ... the downside is costs

18/6 keeps plants in veg, costs less to run and allowes the plants to relax ...... the downside is having to use a timer and making sure it works

the other benefit of 18/6 is that it makes it easier to harden clones to outside....providing the light/dark hours are around the same time....sortof thing

 

 

 

[R.H.Goddard]

The need for a dark cycle ..

http://www.ncbi.nlm.nih.gov/pmc/articles/PMC34891/

http://www.plantcell.org/content/15/5/1212.short

 

They're interesting papers though I'd be careful about applying them to cannabis as the physiology plants can differ greatly.

 

Here's a quote from Rosenthal that delta9 posted in another thread:

 

And his take on 24-0 for veg

http://www.cannabisc...11/06/08/Ask-Ed (Halfway down the page)

 

 

"Marijuana grows fastest under continuous lighting. In experiments performed in the 1980’s plants under continuous light during vegetative had a yield increase of 15-24%. If you are seeking the fastest growth possible during this period, keep the lights on 24 hours a day until the plants are forced to flower. The plants will grow well when they are given a dark period daily, however their growth rate will be slower. The lighting regimen is a choice for the grower to make..."

 

What's pretty annoying about that though is he doesn't actually refer to any papers, publications or anything.

 

According to SensiSeeds:

Sensi Seeds recommends a vegetative photoperiod of 18 hours light, 6 hours darkness in each 24 hour cycle. Some literature advises that lights should be left on 24 hours per day for the vegetative cycle, but we have observed no growth advantage from using this photoperiod.

http://forum.sensiseeds.com/forum_posts.asp?TID=494

(Posted by an admin, quote halfway down page)

 

I've tried searching for some actual marginally scientific papers from properly controlled experiments examining the differences in plants grown under different lighting, but have yet to really find any.

 

Of course veteran growers have definitely done such tests, the issue is though so many of them claim to have done so but at the same time claim to have had drastically different results. While I'd like to trust Rosenthal I find it a bit difficult to really scope out the reliability of his claims without seeing exactly how these experiments were done as well as the actual data.

 

Welcome RH, have you looked at the 12-1 light schedule it's big on the rest period (11hrs) for growth, saves on electricity and theres less heat, less stress on the plants. I have been using 12-1 with no negatives. Anyone that has tried it likes it, but theres plenty of skeptics. I have some diaries here on 12-1 grows, 12-1 is: 12hrs on. 5.5hrs off. 1hr on. 5.5hrs off, then repeat.

 

 

These 2 have only ever had 12-1 from seed, they are a new cross between Tahoe OG Kush & Pineapple Chunk. I thought one was a male, but looks like their both girls

Vrod.

 

Ha ha 12-1 is news to me. Those are some good looking plants though and I'll check the diaries, could be worth a try.

 

 

It doesn't look like it'd really be possible to get a clear cut answer for this. Searching for ages through Google I haven't been able to find any actual experimental data, just plenty of conflicting opinions. Personally I'll probably go with 18/6 to start with for the lower costs, then at some point after I'm fairly confident I know what I'm doing I'll probably make 2 completely identical setups and test it my self; would need to do plenty grows before being able to really draw any conclusions but it'd be good fun

Edited November 24, 2011 by R.H.Goddard

[R.H.Goddard]

24/7 is good to help reveg a plant that has been in bloom....and it also saves the stress of the timer dying ... the downside is costs

18/6 keeps plants in veg, costs less to run and allowes the plants to relax ...... the downside is having to use a timer and making sure it works

the other benefit of 18/6 is that it makes it easier to harden clones to outside....providing the light/dark hours are around the same time....sortof thing

 

 

 

 

Any idea how important it is to keep the photo-period strict? I haven't got a timer yet and I've just been switching the lights on/off at around 18/6. Maybe +- 1.5 hours overall. Then there was a day I couldn't get home so had a full 24 hour thrown in there. Probably not very good... Is this likely to stress the plant much or should she be cool with it?

 

This is an autoflower by the way

[STONEDAJ69]

If you're doing it manual I'd just put em on 24/0

 

 

I don't think it'll harm them to have lights on in their dark period in veg, it's in flower it will cause you problems