OldGrowth420
Well-Known Member
the kind of light(hps/cmh/cfl/lcd/etc) doesnt matter. what you should be concentrating on is the kelvin spectrum (sometimes given in nanometer wavelenghts readings) and the lumen out put. you should also consider the relative heat output from each bulb respectively.
if i may, let me back up my statements. this is definitive, there has been study after study after study regarding specific wavelengths of light that plants absorb. (keep in mind wavelength is the same as Kelvin rating). these "useful" wavelengths are different for every plant(plants in the tropics get more direct sun(less red light) than plants near the poles(more red, due to the angle of the sun's rays))
but anyways, there is a very intuitive reason for why plants use blue and red light.
if you look at the visible light spectrum from left to right, you should realize the colors roy. g. biv. red to the left, green in the middle, and blue to the right. unfortunately i dont have a chalkboard i can draw on to show you what the graph looks like on this forum. but if you can imagine a graph in which amount absorbed is the y axis and wavelength(color) is the x axis. you will see that plants take up a fair amount of the red spectrum, hardly any green, and a fair amount of blue spectrum. the reason why we see a leaf as green is due to the fact that green light is reflected, not absorbed, green light bounces back.
so that was pretty long winded and didnt have much to do with anything, but it is interesting, but is a necessary precursor for the following:
studies have shown that different wavelengths of absorbed light are indeed responsible for the expression of separate hormones, obviously, just like when you got your first pube, your hormone expression was changing and putting your body through the morphological changes associated with puberty. the same in plants. blue light is associated with the summer and IN marijuana associated with vegetative growth. many plants have different genetics that allows for blue light to stimulate flowering. in the fall, you may think of this as when you turned 10, the angle of the sun produces less blue light and a cooler, less energetic red light. the red light sets off a series of second messenger gene cascades( youll have to look that one up, its a whole other topic) that are responsible for proteins and hormones involved in flower formation.
as far as kelvins(or nm), the best way to do it, if money were no option, and if you could find ALL of the proper bulbs, i would try to find bulbs between 1800-3000, i would go with 5 of these, at 1000 lumen apiece. try to get one 1800, a 2000, a 2500, 2700, 3000. (you get the idea.) you really would see major benefit if you could get all of these spectrums together.
in addition to the lower end of the kelvins, you should also try to find 1000 lumen bulbs between 5000-8000, pick 5 bulbs at increments similar to the other ones i just gave as an example.
ideally you should be shooting for 10,000 to 15,000 total lumens from the mixed spectrum, excluding green light which is about 4000k.
on a super sunny summer day, the sun spits out between 10,000 and 25,000 lumens per sq ft depending on ozone, cloud coverage, smog, and a few others things.
more lumens, will make your plants produce more, just as long as the heat is kept in check.
so a recap, mix the spectrums as much as possible, exclude green light~3500k-4500k, shoot for 10,000 lumen or more, if you can. you will still get growth with less lumen, just ultra, ultra slow. from biology lesson
if i may, let me back up my statements. this is definitive, there has been study after study after study regarding specific wavelengths of light that plants absorb. (keep in mind wavelength is the same as Kelvin rating). these "useful" wavelengths are different for every plant(plants in the tropics get more direct sun(less red light) than plants near the poles(more red, due to the angle of the sun's rays))
but anyways, there is a very intuitive reason for why plants use blue and red light.
if you look at the visible light spectrum from left to right, you should realize the colors roy. g. biv. red to the left, green in the middle, and blue to the right. unfortunately i dont have a chalkboard i can draw on to show you what the graph looks like on this forum. but if you can imagine a graph in which amount absorbed is the y axis and wavelength(color) is the x axis. you will see that plants take up a fair amount of the red spectrum, hardly any green, and a fair amount of blue spectrum. the reason why we see a leaf as green is due to the fact that green light is reflected, not absorbed, green light bounces back.
so that was pretty long winded and didnt have much to do with anything, but it is interesting, but is a necessary precursor for the following:
studies have shown that different wavelengths of absorbed light are indeed responsible for the expression of separate hormones, obviously, just like when you got your first pube, your hormone expression was changing and putting your body through the morphological changes associated with puberty. the same in plants. blue light is associated with the summer and IN marijuana associated with vegetative growth. many plants have different genetics that allows for blue light to stimulate flowering. in the fall, you may think of this as when you turned 10, the angle of the sun produces less blue light and a cooler, less energetic red light. the red light sets off a series of second messenger gene cascades( youll have to look that one up, its a whole other topic) that are responsible for proteins and hormones involved in flower formation.
as far as kelvins(or nm), the best way to do it, if money were no option, and if you could find ALL of the proper bulbs, i would try to find bulbs between 1800-3000, i would go with 5 of these, at 1000 lumen apiece. try to get one 1800, a 2000, a 2500, 2700, 3000. (you get the idea.) you really would see major benefit if you could get all of these spectrums together.
in addition to the lower end of the kelvins, you should also try to find 1000 lumen bulbs between 5000-8000, pick 5 bulbs at increments similar to the other ones i just gave as an example.
ideally you should be shooting for 10,000 to 15,000 total lumens from the mixed spectrum, excluding green light which is about 4000k.
on a super sunny summer day, the sun spits out between 10,000 and 25,000 lumens per sq ft depending on ozone, cloud coverage, smog, and a few others things.
more lumens, will make your plants produce more, just as long as the heat is kept in check.
so a recap, mix the spectrums as much as possible, exclude green light~3500k-4500k, shoot for 10,000 lumen or more, if you can. you will still get growth with less lumen, just ultra, ultra slow. from biology lesson
