Is there an answer for perfect light cycle from the start to the end?

Blossom21

Blossom21

Active Member
I tried to talk about this topic with people who don't just give just their own preference and leave, BUT actual done testing with data. But never got real results, just people talking how their preference is the best :D

One thing i'm sure is that the bigger cannabis growers (at least) have tested this to maximize their grow with automacially adjusting leds (and adjusting everyhing to pretty much perfection). But would they wanna share their results to everyone? I'm pretty sure not. Unless someone in the industry leaks it.

Of course this could be tested in multiple identical grow rooms, but that would require time, money and patience that i know most people wouldn't wanna do because their own preference works from the typical 18/24-24h for photoperios and autos, then at the veg bring down their lights for photoperiods at least.

I've alwatys grown with the old 18/6 cycle photoperiods and they turn fine, but is there a faster method proven? Would giving more light in any stage give bigger results? So the answer for this would be nice to be for photoperiods, i don't can about autos.
 
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Horselover fat

Horselover fat

Well-Known Member
No. Not known. Depends.


Maybe you get more strech if you do nights. Maybe. Is it good or bad? Well, me, I want as little strech as possible. Someone else might not feel my style is optimal. So how do we decide which one is optimal? We don't. That's how.

I do 24/7. Works fine. I see no reason to switch, but I have done 18/6 and 20/4, which worked just fine too. I doubt there is a huge difference if DLI is matched.

I did find this bit, but is it a definitive answer? Who knows.

“A GW Pharmaceuticals study compared the growth rates of eight varieties in day length of 18 and 24h. After three weeks the plant in the 18h day length were shorter and lighter than those in the 24h day length. …..
To produce a similar mass of foliage to the plants that underwent 24hr day length for 21 day, the plants in the 18h group required 28 days, at which point the light energy emitted was the same for both plants, thus saving no electricity. ‘ –Handbook of Cannabis – Oxford Press, pg. 75"

edit: they obviously didn't match dli
 
go go kid

go go kid

Well-Known Member
well personaly i disagree with those results, i have done side by side results of some strains and found 24/7 to be the best light hours for more compact plants.
thats not to say that the strains i have not tested will produce stockier plants with 18 hrs. just my own observation with them
 
Horselover fat

Horselover fat

Well-Known Member
go go kid said:
well personaly i disagree with those results, i have done side by side results of some strains and found 24/7 to be the best light hours for more compact plants.
thats not to say that the strains i have not tested will produce stockier plants with 18 hrs. just my own observation with them
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Yeah, I don't know more about the study. My belief is that same DLI will produce same kind of results, but I have no proof. Less light will be less light and less growth.
 
Blossom21

Blossom21

Active Member
Horselover fat said:
No. Not known. Depends.


Maybe you get more strech if you do nights. Maybe. Is it good or bad? Well, me, I want as little strech as possible. Someone else might not feel my style is optimal. So how do we decide which one is optimal? We don't. That's how.

I do 24/7. Works fine. I see no reason to switch, but I have done 18/6 and 20/4, which worked just fine too. I doubt there is a huge difference if DLI is matched.

I did find this bit, but is it a definitive answer? Who knows.

“A GW Pharmaceuticals study compared the growth rates of eight varieties in day length of 18 and 24h. After three weeks the plant in the 18h day length were shorter and lighter than those in the 24h day length. …..
To produce a similar mass of foliage to the plants that underwent 24hr day length for 21 day, the plants in the 18h group required 28 days, at which point the light energy emitted was the same for both plants, thus saving no electricity. ‘ –Handbook of Cannabis – Oxford Press, pg. 75"

edit: they obviously didn't match dli
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Yeah the cannabis study is still at pretty much at the starting point in advanced growing i think, unless mass growers have tested everything already, but i doubt that.

I guess i'll just stay with my own experience and preferences i've gathered. Unless i find a study/studies proving different conditions result in bigger grow.
 
Star Dog

Star Dog

Well-Known Member
Horselover fat said:
Now that I read your post again I'm kind of surprised too. I too would have expected the lower light plants to have streched more, but have less mass.
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Agreed 100%, why do you expect that, it's because you know through experience thats what to expect, idk how a uni arive at their findings when years of experience from multiple growers is to the contrary.
 
Horselover fat

Horselover fat

Well-Known Member
Star Dog said:
Agreed 100%, why do you expect that, it's because you know through experience thats what to expect, idk how a uni arive at their findings when years of experience from multiple growers is to the contrary.
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A quick search didn't come up with the whole study, but I found this, which seems to correlate with our experience.

"A GW Pharmaceuticals study compared the growth rates of eight varieties in day lengths of 18 and 24 h. After 3 weeks the plants in the 18 h day length (mean height 32.3 cm, dry foliage weight 4.00 g) were shorter and lighter than those in a 24 h day length (mean 36.2 cm and 7.34 g). The reduction in height was not statistically significant (paired 2-tailed t-test, p = 0.054) but the weight decrease was highly so (p = 2.53 × 10−5).

Compared to plants grown in 24 h days for 21 days, plants grown more slowly in 18 h days were judged to have achieved a similar stage of development after 25 days. However, there were differences in morphology, which included a significantly greater mean height in the 18 h day length/25-day regime plants (39.7 cm vs. 36.2 cm, p = 0.033). Although they had produced a similar weight of stem, the mean dry weight of foliage was significantly reduced (5.51 g vs. 4.38 g/ plant, p = 0.0011.) An increase in height without a concomitant increase in stem weight results in a less robust plant. To produce a similar mass of foliage to the plants in the 24 h day length/21-day regime, plants in 18 h would have required closer to 28 days, at which point the total quantity of light energy emitted would have been the same. The policy of using a 24 h day length during the vegetative period was hence vindicated by this study."

These are other people writing about the study, so maybe the confusion is theirs. The text is pretty hard to read. In the first paragraph they say the 18h plants seemed shorter at day 21, but not statistically significant. Then in the part I bolded they say they were taller at day 25. Then at 28 days they had the same mass as the 24/7 plants had at 21 days.
 
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go go kid

go go kid

Well-Known Member
the 18h plants seemed shorter at day 21
this is impossabl;e, the plants that are given night time darkness will grow sigificantly more then thoose given 24 hrs of light with no darkness full stop. thats some misleading infoo if you ask me
 
Horselover fat

Horselover fat

Well-Known Member
go go kid said:
the 18h plants seemed shorter at day 21
this is impossabl;e, the plants that are given night time darkness will grow sigificantly more then thoose given 24 hrs of light with no darkness full stop. thats some misleading infoo if you ask me
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They also got less light and thus had less mass. You could say they streched more, because they had less mass, but were still as tall as 24/7 plants.
 
go go kid

go go kid

Well-Known Member
yes ok, i didn't read it properly, but 24 hr light plants grow way shorter and slower to begin with, but ive not tried giving plants less light b4, ive allways grown with 400w or 1000 watt mh lights, so i cant realy coment can i. verry interesting though
 
Horselover fat

Horselover fat

Well-Known Member
go go kid said:
yes ok, i didn't read it properly, but 24 hr light plants grow way shorter and slower to begin with, but ive not tried giving plants less light b4, ive allways grown with 400w or 1000 watt mh lights, so i cant realy coment can i. verry interesting though
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The text is very dense and difficult to read.
 
Frank Nitty

Frank Nitty

Well-Known Member
Blossom21 said:
I tried to talk about this topic with people who don't just give just their own preference and leave, BUT actual done testing with data. But never got real results, just people talking how their preference is the best :D

One thing i'm sure is that the bigger cannabis growers (at least) have tested this to maximize their grow with automacially adjusting leds (and adjusting everyhing to pretty much perfection). But would they wanna share their results to everyone? I'm pretty sure not. Unless someone in the industry leaks it.

Of course this could be tested in multiple identical grow rooms, but that would require time, money and patience that i know most people wouldn't wanna do because their own preference works from the typical 18/24-24h for photoperios and autos, then at the veg bring down their lights for photoperiods at least.

I've alwatys grown with the old 18/6 cycle photoperiods and they turn fine, but is there a faster method proven? Would giving more light in any stage give bigger results? So the answer for this would be nice to be for photoperiods, i don't can about autos.
Click to expand...
18-6 for photos??? How does that work out??? Do any of your plants hermie when doing this???
 
Frank Nitty

Frank Nitty

Well-Known Member
go go kid said:
well personaly i disagree with those results, i have done side by side results of some strains and found 24/7 to be the best light hours for more compact plants.
thats not to say that the strains i have not tested will produce stockier plants with 18 hrs. just my own observation with them
Click to expand...
Are we talking autos or photos grown in these instances???
 
go go kid

go go kid

Well-Known Member
Frank Nitty said:
Are we talking autos or photos grown in these instances???
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photos, ive only grown aytos twice now, very disapointing, although i do have some sensi auto's to try for better genetics.
the tests ive done were on sensi northan lights, white widow from the oriiginal breeder, i forget who it was now and skunk 1 from sensi
 
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