Technical question about light and color

[Heisenbergfan]

I've been doing some research on light and what works best for growing and I have discovered the consensus to be that predominantly blue light is best for early stage growth (vegetation) and predominantly red light is best for later stage growth (flowering).

I have also read many times that the more lumens/watts/PAR/etc. the better.

So I started researching light and color and learned that to produce red, blue or any other color of light from a particular light source, the other wavelengths of light must be filtered out (or subtracted) so that only the wavelength desired remains.

In other words, a "red" light source is basically a potentially more luminous white light source (that would contain all the reds you would be producing with the red "filter" on) plus more light which is also deemed beneficial widely by this community.

In essence, it seems to me that you get less total light with colored lights and gain absolutely nothing because the unfiltered light would already produce the same amount of any particular color after filtering out the other wavelengths.

To put it simply. Coloring light = subtracting light.

Thoughts?

 

[The303Stoner]

you want the most PAR Photo Active Radiation. white light is all colors present. with L.E.D. YOU CAN GET RED AND BLUE only. with HIDS you get wide spectrum light witch has yellow and makes heat. I think the plasma lights look awesome like the Eye Blue enhanced but stronger

 

[Hosebomber]

The light "color" that any bulb gives off is a by product of how/what makes up that bulb. The chemicals inside the bulb/tube/diode determines what color the light puts out. HPS uses sodium under high pressure. There is also a low pressure sodium. MH uses mercury vapor or other prospers as does LED's. So generally speaking your statement is incorrect. Other prospers can be added to reflect the lighting to a different color temperature. It doesn't really block the other light just skews the visual results.

 

[Hemposaurus42]

The light provided by the bulbs isn't phased out, it just changes the visual result. You are still providing the necessary light spectrum to your plant, even if you mix color temps, as long as the majority of the light comes from the right spectrum.

For example im using 4x 42w CFL bulbs with a temp of 2700k, but I also use 2x 20w CFLs that provide a small amount of 5000k. This helps supplement all the natural light that a plant would recieve from the natural photo phases of the sun throughout the day. The only main reason for the switch in temp is because plants are used to shorter days in some parts of the year, making the sun's main visual appearance mostly red. This is also the reason for switching your light period.

The main reason this whole color temp thing matters is to stimulate better results during flower.

 

[jlt1202]

The light provided by the bulbs isn't phased out, it just changes the visual result. You are still providing the necessary light spectrum to your plant, even if you mix color temps, as long as the majority of the light comes from the right spectrum.

For example im using 4x 42w CFL bulbs with a temp of 2700k, but I also use 2x 20w CFLs that provide a small amount of 5000k. This helps supplement all the natural light that a plant would recieve from the natural photo phases of the sun throughout the day. The only main reason for the switch in temp is because plants are used to shorter days in some parts of the year, making the sun's main visual appearance mostly red. This is also the reason for switching your light period.

The main reason this whole color temp thing matters is to stimulate better results during flower.

TRUE reason that plants react to warmer RED spectrum light waves because of the fact that Red light travels the farthest, thats one of the reasons the sky is blue(shorter wavelengths, because our brain likes that better), but in fall (when the earth turns away from the sun) the days will get shorter and the ONLY wavelengths then are geting are the RED because of the distance of the sun.

NOW to change that for a man made grow set up. Color Temp does not "phase out" with distance, but your LUMUNS will.

SO RECAP;

Veg your going to want some red but also you want to have a good amount of spectral colors that can go down to 270nm wich is your deep blue (white/blue light)

Flower you want to simulate that the days are getting shorter by changeing light times, and only giving the plant red (MOSTLY RED, other spectrum are usefull but yellow and red dominate) which makes the plant think the sun is getting farther away from the plant.

Tip; When flowering, dont be too literal and move the light source farther away attempting to 'move the sun farther away'. REMEMBER farther the light is from the plant the less LUMUNS that the plant can absorb. So your burning electricity for nothing at that point ; /

 

[Hosebomber]

jlt, you are off on a couple of things. The sky is blue due to the scattering of the wavelength by particles in the atmosphere. The sky has a red tint in the fall due to the scattering occurring in the upper atmosphere and the refraction angle being above the sight line. The human eye prefers the 525 (green) wavelength.

Blue light is between ~420-490 nm. Violet is from ~380-420nm. Below 380nm is UV or ultra violet.
You want more red light during flowering due to the chemical changes in the plant that need to occur in the production of the flowers. Adding UV and low blue light during flowering will increase resin production as a defense mechanism of the plant. The plant is trying to keep the species alive and therefore will use the stored energy in the leaves to produce the flower and any new energy will be used to defend itself from predators.

You are partially correct on your tip. Moving the light away from the plant does not help at all. However it has nothing to do with lumens. Lumen is a measurement of how bright a light is to the human eye and has nothing at all to do with plants. Less photons will hit the plant due to inverse square law. That means the plants have less energy to convert.

 

[jlt1202]

jlt, you are off on a couple of things. The sky is blue due to the scattering of the wavelength by particles in the atmosphere. The sky has a red tint in the fall due to the scattering occurring in the upper atmosphere and the refraction angle being above the sight line. The human eye prefers the 525 (green) wavelength.

Blue light is between ~420-490 nm. Violet is from ~380-420nm. Below 380nm is UV or ultra violet.
You want more red light during flowering due to the chemical changes in the plant that need to occur in the production of the flowers. Adding UV and low blue light during flowering will increase resin production as a defense mechanism of the plant. The plant is trying to keep the species alive and therefore will use the stored energy in the leaves to produce the flower and any new energy will be used to defend itself from predators.

You are partially correct on your tip. Moving the light away from the plant does not help at all. However it has nothing to do with lumens. Lumen is a measurement of how bright a light is to the human eye and has nothing at all to do with plants. Less photons will hit the plant due to inverse square law. That means the plants have less energy to convert.

guess i need to be less lazy and get MORE technical lol i miss remember some of my shit and yes to the sky crap haha i hate ozone because of how many diffrent variables.

But Lumens DO drop farther the light sorce is away from the plant (even tho small) can effect the ACCUAL output of your lights thats all

 

[tmcguire1989]

This is an old tread but I figured I would still chime in. Far red light (730nm) instantly activates phytochrome telling the plant it is flowering. Any other light would take up to 2 full hours to activate. There is a reason you get smaller yiels (typically) from a MH in flower and I cant help but think that blue light may take longer to get the message to your phytochrome.

 

[The303Stoner]

Glass will absorb and reflect light wave lengths from your bulb lowering the value reaching the plant. Never put a UV light behind glass because the glass will block most of the UV rays.