It has been brought to my attention that more then a few people have been getting confused on light spectrums and which ones are better for which stage. Below is a picture that I have edited from Marijuana Seeds Search Garden that divides the kelvin light spectrum in half and tells you which one you would like to use more in what stage. It is posted in another topic and it was brought up to do this. I hope this helps some people out down the road. Thank you all (especially MR. ISSUES).

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USEFUL LINKS

Marijuana Light Spectrum
Higher Female Ratio
Foliage Feeding
Drying & Curing Marijuana
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Yea Rock On That'll Help People Out A Lot!!!

except for one thing, incandescent and halogens cant be used

Well they can be used, but they are just not ideal for growing.

__________________
Accept who you are and live how you're suppose to....that is freedom.

USEFUL LINKS

Marijuana Light Spectrum
Higher Female Ratio
Foliage Feeding
Drying & Curing Marijuana
Grow Room Ventilation
Usefullness of Males

induced strecthing, nah ill pass

Haha I hear ya man. I would never even consider using either one. Nice post bro!

__________________
Accept who you are and live how you're suppose to....that is freedom.

USEFUL LINKS

Marijuana Light Spectrum
Higher Female Ratio
Foliage Feeding
Drying & Curing Marijuana
Grow Room Ventilation
Usefullness of Males

thanks pauliojr

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......but growing it IS.

It seems like I keep hearing contradictions. I read in a grow book that 5,000 is closest to the sunlight so it can be used thruout the grow; but that plants use more red in the flowering. I have heard from the grow shop that 6,400k is the prefered spectrum because it's the brightest and the 2,700k red is less bright, so the idea of more red durring flowering is BS.

This chart is different from one I found online which puts pure white sunlight at 5,000k.

What's the deal? I'll check the archives...

Ok, here's the spectrum I found online. It looks closer to the understanding of the grow specturm because 5500k is the 'white' light. Can anyone verify this?

Attached Images

Color_temp.png (2.4 KB, 236 views)

hiya daydrops

Forget 'brightness' it's not relevant.

The suns 'real' kelvin temperature is somewhere around 5,800 degrees kelvin, but because the sun is not a perfect 'black body' (the standard for calculating kelvin temperatures of light) its adjusted kelvin temperature is somewhere around 6,400 degrees kelvin.

6,400 degrees kelvin is predominantly 'bluish-white' light and this is the best kind of light and kelvin temperature for vegetative growth - primarily because in nature the time of year Cannabis is in vegetative growth is during the long hot days of summer where the suns daylength is the longest and receives the most 6,400k light. The reasons it changes for flowering is again because of the predominance of the kind of light found from the sun when Cannabis enters it's floral stage - usually at the start of Autumn or Fall when the days get shorter and the nights longer thus reducing down the daylength significantly. Sunrise and Sunset account for almost 50% of the suns light during the short days of Autumn/Fall and sunrise and sunset are made up of almost entirely red spectrum light due to the angle of the suns rays hitting the earths surface. Therefore as sunrise and sunset account for almost 50% of the sun total light output at that time of year it necessarily follows that 50% of that light will be entirely in the red end of the visible spectrum - hence the 2,700k colour temperature being favoured for flowering. In reality a mixture of red and blue light is required in flowering due to the other 50% of the spectrum being more blue in colour.

great tutorial, babygro. thank you.

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This proves my theory!