Radiative intensity, is it really true higher blue spectrum creates more females in vegetation?

U

unbindmoney

Active Member
Hey guys after reading around 3 grow books, I stumbled on a part by Ryan Riley's Growing Elite Marijuana where he says that during seedling/vegetation that higher blue spectrum will increase the odds of your plants being female, is this true?

If so I was thinking about switching out my 36V, 3500k, 80 CRI Citizen COBs to 36V, 6500k, 80 CRI Citizen COBs. What I don't understand is Radiative intensity.

For the 3500K COBs @ 100% Radiative intensity = ~600 nm.

As for the 6500K COBs @ 50% Radiative intensity= ~550 nm, and @ 20% Radiative intensity = 480 nm

1) So I guess the question is what is Radiative intensity?

2) How do I control the output (1-100%) of Radiative intensity? Would it be by dimming my lights down on my driver?

3) If it is true that more blue spectrum promotes female growth, how would I achieve 20% radiative intensity for the 480 nm?

Thanks guys for any help!
 
Roger A. Shrubber

Roger A. Shrubber

Well-Known Member
i've never heard that. all i've ever heard about blue light is it promotes compact bushy growth, and is good for vegging.
a lot of people veg under very blue metal halide light, wonder if they have a better rate of female to male than people who veg under white led or red/orange hps?
 
U

unbindmoney

Active Member
Roger A. Shrubber said:
i've never heard that. all i've ever heard about blue light is it promotes compact bushy growth, and is good for vegging.
a lot of people veg under very blue metal halide light, wonder if they have a better rate of female to male than people who veg under white led or red/orange hps?
Click to expand...
I'm also wondering if there is a difference between between light spectrums (nm) for COBs and other lights like MH/HID/CFL. Because my COBs are white lights from what I understand and was wondering if the 6500k temperature makes it emit more blue spectrum light.
 
mauricem00

mauricem00

Well-Known Member
unbindmoney said:
Hey guys after reading around 3 grow books, I stumbled on a part by Ryan Riley's Growing Elite Marijuana where he says that during seedling/vegetation that higher blue spectrum will increase the odds of your plants being female, is this true?

If so I was thinking about switching out my 36V, 3500k, 80 CRI Citizen COBs to 36V, 6500k, 80 CRI Citizen COBs. What I don't understand is Radiative intensity.

For the 3500K COBs @ 100% Radiative intensity = ~600 nm.

As for the 6500K COBs @ 50% Radiative intensity= ~550 nm, and @ 20% Radiative intensity = 480 nm

1) So I guess the question is what is Radiative intensity?

2) How do I control the output (1-100%) of Radiative intensity? Would it be by dimming my lights down on my driver?

3) If it is true that more blue spectrum promotes female growth, how would I achieve 20% radiative intensity for the 480 nm?

Thanks guys for any help!
Click to expand...
sounds like what you are calling "radiative intensity is the wavelength where the output of the phosphor peaks. it is fixed by the chemistry of the phosphor and can not be changed.for controlling stretch you want a lot of 450nm light. the spectral distribution chart on page 12 of the cree CXA 3590 data sheet may help you see how the output energy of a white led is distributed
 

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U

unbindmoney

Active Member
mauricem00 said:
sounds like what you are calling "radiative intensity is the wavelength where the output of the phosphor peaks. it is fixed by the chemistry of the phosphor and can not be changed.for controlling stretch you want a lot of 450nm light. the spectral distribution chart on page 12 of the cree CXA 3590 data sheet may help you see how the output energy of a white led is distributed
Click to expand...

Thanks CREE calls it Relative Spectral Power (on the Y-axis of the chart). I should've linked where I was getting these numbers from: http://ce.citizen.co.jp/lighting_led/dl_data/datasheet/en/COB_5/CLU048-1212C4_P3368_1115.pdf (PG 7)

So what you're saying is Radiative Intensity/Relative Spectral Power cannot be adjusted?
 
mauricem00

mauricem00

Well-Known Member
unbindmoney said:
Thanks CREE calls it Relative Spectral Power (on the Y-axis of the chart). I should've linked where I was getting these numbers from: http://ce.citizen.co.jp/lighting_led/dl_data/datasheet/en/COB_5/CLU048-1212C4_P3368_1115.pdf (PG 7)

So what you're saying is Radiative Intensity/Relative Spectral Power cannot be adjusted?
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no it is fixed.you can supplement your spectrum with monos but there is no way to get a significant shift in the spectrum of a diode. I always use feminized seeds or clones from female plants so I don't know if light would have an effect on gender but for a mother plant low intensity will slow growth. 6500K CFLs or T5s have a lot of full spectrum blue light and will keep a plant short and bushy 50-100 watts should be enough to keep a mother plant healthy. I run a single 55watt 2G11 CFL (PL-L 55) on my mother plant and root clones in the same closet
 
U

unbindmoney

Active Member
mauricem00 said:
no it is fixed.you can supplement your spectrum with monos but there is no way to get a significant shift in the spectrum of a diode. I always use feminized seeds or clones from female plants so I don't know if light would have an effect on gender but for a mother plant low intensity will slow growth. 6500K CFLs or T5s have a lot of full spectrum blue light and will keep a plant short and bushy 50-100 watts should be enough to keep a mother plant healthy. I run a single 55watt 2G11 CFL (PL-L 55) on my mother plant and root clones in the same closet
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Just a quick question. If you had to choose between a 4000k or 6500k light for vegetation which one would you go with? 4000k is still in the lighter blue spectrum right?

Thinking about maybe going 2 4000k COBs and 2 6500k COBs, I hear some red light spectrum is needed for vegetation. Trying to run 1 bonzai clone mother in a 2'x2'x4' veg tent with some other clones, seedlings, and plants.
 
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mauricem00

mauricem00

Well-Known Member
unbindmoney said:
Just a quick question. If you had to choose between a 4000k or 6500k light for vegetation which one would you go with? 4000k is still in the lighter blue spectrum right?
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I would choose 6500K. 4000K is closer to a flowering spectrum and may cause stretching during veg.5000 to 6500k are commonly used for veg lights. my plant grow to 3 times their height in flowering so I like to keep them short and bushy in veg so I don;t outgrow my flowering room
 
Olive Drab Green

Olive Drab Green

Well-Known Member
unbindmoney said:
Just a quick question. If you had to choose between a 4000k or 6500k light for vegetation which one would you go with? 4000k is still in the lighter blue spectrum right?

Thinking about maybe going 2 4000k COBs and 2 6500k COBs, I hear some red light spectrum is needed for vegetation. Trying to run 1 bonzai clone mother in a 2'x2'x4' veg tent with some other clones, seedlings, and plants.
Click to expand...
Honestly, pure white 3500k works best.
 
U

unbindmoney

Active Member
Olive Drab Green said:
Honestly, pure white 3500k works best.
Click to expand...
Getting Citizen COBs and I think 3500k pure whites give of ~600 nm closer to the red spectrum. From what I'm reading ~600 nm red range has no chlorophyll benefits while 6500k will give off ~440 nm and 4000k will give of ~590 nm a good mix of blue and light red spectrum.

Also from what I'm reading the optimal chlorophyll absorption peaks @ 439 - 469 nm and the 4000k COBs will also put out ~450 nm @ 90% radiative intensity (as well as ~590 nm @ 100% radiative intensity). So 2 COBs giving off a lot of blue spectrum and 2 COBs giving off a good amount of blue and red spectrum.


EDIT: http://ce.citizen.co.jp/lighting_led/dl_data/datasheet/en/COB_5/CLU048-1212C4_P3368_1115.pdf


Page 7, shows that chart, also I might be completely misinterpreting this chart.
 
U

unbindmoney

Active Member
mauricem00 said:
I would choose 6500K. 4000K is closer to a flowering spectrum and may cause stretching during veg.5000 to 6500k are commonly used for veg lights. my plant grow to 3 times their height in flowering so I like to keep them short and bushy in veg so I don;t outgrow my flowering room
Click to expand...
In Color Spectrum/Temperature I heard CFLs and LEDs are pretty close in comparison with LEDs being a little better (?) and so I did some comparison with CWL's VegMaster and here are its specs:

https://californialightworks.com/wp-content/uploads/2016/01/SolarStorm_220_SpecSheet_2015.pdf


compared to a 4000k Citizen 1212 CLU048 36V, 4000K, 80CRI

http://ce.citizen.co.jp/lighting_led/dl_data/datasheet/en/COB_5/CLU048-1212C4_P3368_1115.pdf (pg7)


Very similar except a little less red spectrum on the 4000k COBs. What do you guys think? Are LEDs and CFL's color spectrum/color really that similar to make this comparison?
 
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