# Another debate question for the experts



## Hushpuppy (Sep 2, 2011)

So I have been doing a lot of reading about lights, and the spectrums of light that plants use. I have read some interesting information that light in the "actinic blue" range(450nm) is good usable light for plants. But an interesting thing with this spectrum, if I understand correctly, is that it has the same properties of inducing the flowering hormone while also feeding chlorophyll energy as well.

I am wondering about using this light along with the HPS, but while the HPS would turn off after 12hrs, the actinics could stay on for another 4hrs to feed the plants and prevent "stretch" without disturbing the flowering light cycle.

I have also read that this can be done with the UV deep blue lighting as well without disturbing the light cycle, but supplying the extra needed energy to prevent "stretch".

Has anyone heard of doing this? Any good or bad results from trying it? I know this gets into splitting hairs with preventing "stretch" and causing "stress". I just like investigating new techniques, and the science of it all fascinates me.


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## Growdude (Sep 2, 2011)

Hushpuppy said:
			
		

> So I have been doing a lot of reading about lights, and the spectrums of light that plants use. I have read some interesting information that light in the "actinic blue" range(450nm) is good usable light for plants. But an interesting thing with this spectrum, if I understand correctly, is that it has the same properties of inducing the flowering hormone while also feeding chlorophyll energy as well.


 
Gotta link to what you read?  never heard of this before. thxs


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## bho_expertz (Sep 2, 2011)

Send that link !!!


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## Locked (Sep 2, 2011)

Yes a link wld be most excellent...sounds like interesting stuff.


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## mr_chow (Sep 2, 2011)

blue spectrum lighting during veg is most beneficial for short internodal lengths and propagation of females...i've read this before.

...red spectrum lighting is supposed to be beneficial for flower growth.


i had a couple of hydrofarm 400w MH lamps with bulbs that were supposed to have more red spectrum than other MH bulbs...used them throughout the whole grow w/o switching.  had some good results...but never did any comparative testing.


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## Growdude (Sep 2, 2011)

mr_chow said:
			
		

> blue spectrum lighting during veg is most beneficial for short internodal lengths and propagation of females...i've read this before.
> 
> ...red spectrum lighting is supposed to be beneficial for flower growth.
> 
> ...


 
This we know. Its the blue light that wont interupt flower part ive not heard of.


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## Sol (Sep 2, 2011)

What is the 'UV deep blue spectrum'? Is that the proper name for the ultra voilet light that we all know of in everyday applications or is it just part of the standard blue spectrum that we try to recreate with artificial lighting specially for plants. 
 In short, i'm asking would this source of light come from a UV bulb or an HID with enhanced blue spectrum? That makes more sense ,right?


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## mr_chow (Sep 2, 2011)

Growdude said:
			
		

> This we know. Its the blue light that wont interupt flower part ive not heard of.




ah, just reread the post.  interesting.

...i only thought green-light would not disturb flower, but now thinking about it, how would cannabis flower in the artic w/o being disturbed by the 24-hrs of light??


hmmm, interesting topic, for sure.  i'm in...


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## mr_chow (Sep 2, 2011)

http://www.marijuanapassion.com/forum/archive/index.php/t-8339.html

^from 2007


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## mr_chow (Sep 2, 2011)

wanna know the "truth", you gotta go to the experts

hxxp//mjgrowers.com/book_what_exper1.htm
_GREEN AND BLUE LIGHT AT NIGHT (by Ed Rosenthal)_
_As plants evolved for hundreds of   millions of years they never actually had to deal with separation of   light spectrums or unusual lighting regimes. When they received light   it came from the sun in a mixture of spectrums and they could pick  and  choose which to use. It was only with the advent first of gas and  then  electric lighting that plants encountered unusual regimens and   splintered spectrums._
_Plants measure day length using the red   light spectrum. While they use other spectrums for other purposes,  they  are not sensitive to them as far as flowering is concerned. They  are  almost totally insensitive to green light and for this reason  reflect  it back to us while absorbing most other spectrums. _
_Plants&#8217; insensitivity to green light  can  be used to a gardener&#8217;s advantage. You know that turning the  light on  in the middle of the dark cycle disturbs the plants&#8217;  flowering  paradigm. The light, HPS, fluorescent and MH lamps all emit  red light.  Green fluorescent and LED lights contain no red light and  will not  disturb the dark period. You can go in the garden under  adequate light  to work, as long as it is green._
_Plants use blue light for certain   regulatory processes and also for photosynthesis. Chlorophyll absorbs   both blue and red light and uses the light&#8217;s energy to power the   complex process in which water and atmospheric carbon dioxide are   converted to sugar and oxygen gas. Blue light does not affect the   regulation of flowering. _
_When blue light is turned on during the   dark period, plants photosynthesize but their flowering isn&#8217;t  affected.  This results in more growth as the plants produce more  sugars. Before  LED lights it was difficult to create a pure blue  light. Instead, most  of the time other spectrums were filtered out,  which can be an  inconvenient process. Try using between 20 and 40  watts of mixed blue  light per 1000 watts of regular light.  I have  done only initial  experimentation with this so test this in a limited  way first. I  suspect that the additional light is an efficient way of  increasing  total yield _
_           Aside from red and blue light, plants   also use orange light for photosynthesis. I haven&#8217;t experimented  with  them yet, but orange LEDs might also help increase yield and  probably  can be lit continuously, just like the blues. More on this  as the news  breaks&#8212;or at least, as it fractures._


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## Locked (Sep 2, 2011)

Very interesting...


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## stevetberry (Sep 2, 2011)

I am on my 8th grow and I have a constant monitoring meter that has a blue display and it has not caused any problems.  I also go into my grow room at least 4 or 5 times during the dark period per day using a green LED flashlight and have had no problems.  A little off subject but I have seen many posts telling not to interupt the dark cycle but it can be done with care.


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## Growdude (Sep 3, 2011)

stevetberry said:
			
		

> I am on my 8th grow and I have a constant monitoring meter that has a blue display and it has not caused any problems.  I also go into my grow room at least 4 or 5 times during the dark period per day using a green LED flashlight and have had no problems.  A little off subject but I have seen many posts telling not to interupt the dark cycle but it can be done with care.


 
Why would you need to go in your gow 4 or 5 times a night?

Thxs Mr Chow for the read.


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## bho_expertz (Sep 3, 2011)

Anyone knows which equipment gives just blue spectrum ? Any links ? Thanks.
This is good stuff :aok:


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## BBFan (Sep 3, 2011)

Interesting read.  Thanks for the post mr chow.  Does anyone know anything about these lights that produce only true blue light in the right spectrum?


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## nouvellechef (Sep 3, 2011)

Kool new stuff. But have no idea why you would need to be in the garden at lights out. Now, if it increased resin production or yield. I am down with it. Other than that. I do like keeping girls up all night, but girls need sleep too.


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## mr_chow (Sep 3, 2011)

at the last kushcon there were some fools selling some led lighting...hempcon is coming up so i'll ask around.  ...will let you know if i find out anything.



peace,

mr_chow


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## Hushpuppy (Sep 5, 2011)

Sorry to take so long to get back to everyone here. had to go out of town. I don't have a link for the information. I read it in my books from Ed Rosenthal and Greg Green. I saw some bulbs online called "actinic" which are supposed to emit light specifically at 400-450nm, which according to the books is at the level that gives light energy to the plants for photosynthesis but doesn't interfere with the photocycle.  

Here is a link to the T5 actinic light: hxxp://www.specialty-lights.com/531060.html

The UV deep blue is another light that I saw online that emits only UVB light and appears deep blue, almost like a "black light". unfortunately, I don't remember where I saw it.


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## Hushpuppy (Sep 5, 2011)

Solanero said:
			
		

> What is the 'UV deep blue spectrum'? Is that the proper name for the ultra voilet light that we all know of in everyday applications or is it just part of the standard blue spectrum that we try to recreate with artificial lighting specially for plants.
> In short, i'm asking would this source of light come from a UV bulb or an HID with enhanced blue spectrum? That makes more sense ,right?


Yes the UV is the ultraviolet lights. There are 2 types, UVA and UVB, that are becomeing well known because of tanning, sunburn, and sunglass issues. I can't remember where I read it but there was something said about UV light have the property of positively effecting the flowering while also still supplying considerable photo energy.

I think the actinic bulbs don't emit so much of the UV light but more specifically the 420nm wavelength of regular light, which I think is just below the UV range. It is still in the visible spectrum I believe.


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## BBFan (Sep 6, 2011)

Hushpuppy said:
			
		

> Yes the UV is the ultraviolet lights. There are 2 types, UVA and UVB, that are becomeing well known because of tanning, sunburn, and sunglass issues. I can't remember where I read it but there was something said about UV light have the property of positively effecting the flowering while also still supplying considerable photo energy.
> 
> I think the actinic bulbs don't emit so much of the UV light but more specifically the 420nm wavelength of regular light, which I think is just below the UV range. It is still in the visible spectrum I believe.


 
Actually there are 3 types UVA, UVB, and UVC.  Clarke, in _MJ Botany_, discusses the role of UVB lighting and it's effects on the metabolic pathways of thc.  I've never seen anything written or discussed whereby it positively affects flowering.  There has been much debate on whether UVB influences the production of trichomes as a defense mechanism.


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## Hushpuppy (Sep 6, 2011)

I went back and looked at some of the information that I had seen. Unfortunately I can't find the info online that I had read earlier. The information that initiated my interest in the "blue light" comes from Ed Rosenthal's book, "Marijuana Grower's Handbook", which is an "official course book for Oaksterdam University" in California.

I read on the lighting that, according to Ed, UVA and UVB are beneficial light spectrums that plants recieve from the sun in limited amounts, while UVC has no apparent use for the MJ plant. UVB light from 290-320nm appears  to encourage the production of THC, flavonoids, and terpenes, while UVA seems to contribute to photosynthesis and other responses within the MJ plant.

The interesting part that (may be useful for us as growers) is the flowering hormone that is directly responsive to light spectrum and the dark period. 

Ed says that the hormone Phytochrome (pr/Pfr) has 2 states within the plant. The inactive state(Pfr) occurs during extended light periods when the plant is absorbing the different spectrums of light. When the plant is placed into full darkness for the proper period of time(12+hours) then the hormone changes to its active form (Pr), which after a few days of high active levels will encourage the plant to switch to the flowering phase.

All that being said, Ed stated that there are two spectrums that affect the hormone Pr/Pfr, the red spectrum around 660-666nm and the blue spectrum around 400-450nm. Any interruption of the dark period with the red 666nm light will cause the Pr hormone to revert back to its inactive form Pfr. 

Blue light around the 450nm also has the same effect but to a much lesser degree. At the same time this blue light will encourage plant growth through the transfer of light energy to the chlorophyll. 

Ed gives this information for the purpose of being a viable method of sexing plants without disturbing the growth cycle and forcing the plant into full flowering. The method is to have the "blue" spectrum of light on for the 12hour dark period of a 12/12 photoperiod. Having this "blue" light on during the dark period supplies enough energy to support growth while not discouraging enough production of the hormone Pr to produce a limited flowering response.

My hypothesis is; if I were to use a significant amount of "blue 420-450nm" light for only 4-6 of the 12 hours of dark period, I could offset the "stretch" that occures as a result of the plant getting less light after the switch to the 12/12 photoperiod, without affecting the flowering response.

At this point I don't have any data to support my hypothesis other than the information supplied by Ed Rosenthal and a little that I read online. That is why I posed the question here to see if anyone else has heard or considered this. At this point I would not recommend that anyone go out and buy "Actinic" or "black" lights. I intend to do some experimenting with this in the near future and will update everyone when I find out more.


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## bho_expertz (Sep 6, 2011)

I'm gonna buy ... Or will not ?

No i will wait 

:48:


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## BBFan (Sep 6, 2011)

Hushpuppy said:
			
		

> I read on the lighting that, according to Ed, UVA and UVB are beneficial light spectrums that plants recieve from the sun in limited amounts, while UVC has no apparent use for the MJ plant. *UVB light from 290-320nm appears to encourage the production of THC, flavonoids, and terpenes*, while UVA seems to contribute to photosynthesis and other responses within the MJ plant.


 
Hushpuppy- This hasn't been proven to be true. I've been experimenting with UVB lighting for a few grows now over the last couple years and still haven't gotten definitive results. And certainly no-one in the scientific community supports or has verified this statement to be true. Also, UVB  rays are harmful to plants, not beneficial. If UVC could get through our atmosphere- there would be no life on the planet!

And phytochromes (there are many types) are not the defining receptor to induce flowering. Florigens are an elusive hormone that the scientific community has yet to isolate but is what is generally accepted to be the inducer of floral onset in photoperiod plants. The Circaidian Rhythm is what it is. The start of the flowering process goes hand in hand with other processes, most notably senescence. (PfR is the active state of phytochromes, not the other way around).

There are many tried and true ways to reduce stretch that have been used in the horticultural field for years. If there's a way to continue vegetative growth during the onset of flowering, I'd be real interested in reading more about it. But somehow I'm thinking it's not possible.

Interested to see how it works for you.


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## NorCalHal (Sep 7, 2011)

Ed smokes too much............


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## BBFan (Sep 7, 2011)

Yeah Hal.  I wasn't gonna say that.  Taking some liberties.


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## Sol (Sep 10, 2011)

Right ,that's what i was wondering. Same deal i'm sure i read something about uv lights as well, a long time ago. Then when you reminded me of it , i thought " i have a UV light' like a blacklight. Its a florescent* bulb as well, not an incandescent one. Might be interesting if it had some effect.


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## mr_chow (Sep 10, 2011)

Solanero said:
			
		

> Right ,that's what i was wondering. Same deal i'm sure i read something about uv lights as well, a long time ago. Then when you reminded me of it , i thought " i have a UV light' like a blacklight. Its a florescent* bulb as well, not an incandescent one. Might be interesting if it had some effect.



be careful ...  blacklight isn't the same wavelength as actinic


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## Roddy (Sep 10, 2011)

hmmm....interesting!


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## depetreono (Oct 5, 2011)

Once I started reading this thread I couldn't stop. I'm hooked. Let me know how the tests go. Idk if this IS possible but I'm crossing my fingers hopeing you prove it is. This would mean huge increase in yields made in the same amount of time as what we do know. On a profit stand point this could mean seriouse increase in dough. Also more for my own personal use. I'm following this to the end... Keep the knowledge coming guys. And I think led lights are made to produce the exact light or mixture of light you want. But kinda pricey.


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## soil (Oct 7, 2011)

Hushpuppy said:
			
		

> My hypothesis is; if I were to use a significant amount of "blue 420-450nm" light for only 4-6 of the 12 hours of dark period, I could offset the "stretch" that occures as a result of the plant getting less light after the switch to the 12/12 photoperiod, without affecting the flowering response.



hey hush,
IF ed has correct data then i would think your theory should "work". (your thinkin like me......between the lines. )

I have very limited knowledge on uv in general , but BB seems to know his "reefer science" so thats the man i would stick with for testing/advice...... if you ever get that far.


extra , probably un-needed info: 
I use an extra blue MH an a regular HPS together for bloom and always have. i have seen little to no difference using 100% MH for bloom or 100% HPS for bloom. 







soil


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## depetreono (Oct 7, 2011)

So just for understanding.. you can actually keep light on during the dark period of flowering up to a certain point without disrupting the dark cycle and reverting the plant back to veg if you use ONLY a true blue light between 420-450. Which also for my understanding means only blue light no other colors from the light spectrum. Is this correct?? And does anyone know if this can be accomplished with the new led lighting systems?


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## Sin inc (Jan 15, 2013)

well i have always used a 175 watt mh with hps in my flowering room. i am growing cfl right now but .when i do get some money its will 250 mh with a 400 watt hps, i really have not had a prob with streching i feel like its because of the mh stop the strechwhen i use it with my hps


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## Hushpuppy (Jan 15, 2013)

I am sorry that I never came back and finished this thread. I lost it and then forgot about it. 

*Ultimately the blue lights failed *to do what I had hypothesised. They actually cause more stretching because they kept the plants from going into bloom while not giving enough light energy to prevent stretching.


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## Sin inc (Jan 16, 2013)

thanks for the update hush


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