Would mirrors help indoors?

Oleg

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A natural light source eliminates the falloff given the suns distance, dispersion of the reflected light has the same falloff as mentioned above. Enclosing a tent around a LED tube or bulb will greatly reduce the falloff, while one sq inch will disperse the light in 180 degrees leading to falloff, the sq inch next to it will do the same augmenting the light lost by the first inch on the targeted leaf. If you do this with a window as your light source and avoid shading the reflector with the tree you will see next no falloff, the shaded side becomes almost as bright as the sunny side. The angle and position must be considered, a reflector angle at 45 degrees with vertical source will light the edge of the leaf, not very useful, a 45 degree light source and vertical reflector positioned above the targeted leaf will light the top of the leaf. A light meter would be very valuable for placement.
 

sparklemotion

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The problem is in order to reflect UV light the surface has to be vary smooth and refined. We are taking smoother then glass and heavily polished. Im sure you can find something that is made for it but you might be paying for it.
Plants don't photosynthesize light in the UV spectrum.
 

Oleg

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Mylar would be more efficient than white, foil is cheaper but both need a support that will warp with humidity. White styro sheets are great, very white and self supporting but I found they all have a vapor barrier (green here) both sides. Could not find white last time I looked.
 

Wires_Guy_wires

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Guys, just let me make clear that plants do not require UV light to thrive. The entire UV discussion is a waste of time. Plants like it, but they don't need it. The ideal spectrum for plants is still in the visible part of the wavelengths (blue and orange and some red light).

Glass filters all light, double glass even more. A mirror reflects light dead on, the angle of entry is the angle of reflection, that kind of stuff. In grow tents and camera-thingies, they tend to use coarser material because it reflects in all directions.
One problematic thing we see annually in pot growers, is that they burn down the neighbors shed (or their own plants and house) because a mirror can cause serious concentrations of sunlight, sometimes acting like a magnifying glass. Back in the days, Archimedes devised a Death Ray with some mirrors, which didn't work that well but still people accidentally set things ablaze every summer by forgetting about it. You'd need to both counter that, and take into account that the sun doesn't stay in the same location during the day, and that shift continues to change every day. Ever seen a motorized mirror? I haven't. Too much effort to keep it going.

Coarser reflective material keeps on shining, albeit less intense, but more thorough and more evenly during the entire day. The chance to get 'hot spots' is way smaller.
Would it help? Sure, a little. But it might make your neighbors angry, since it'll be shining in their face too.
White plastics or even regular white wall paint reflects almost as much light as coarse metallic material. That's where the white color comes from..

But are you willing to change your windowsill to a somewhat building-site looking one, or do you want to keep it clean and see your trees throughout the day? That is, if we're talking window sills. I don't know about the grow area.

My enclosed indoor grow area has a nice backdrop that I enjoy, and instead of going with reflective material, I just added a few extra high intensity LED lights. With highly reflective material, I can still manually create hot spots though. So I believe white paint or scattered reflection is better.
 

bluesky

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There's a very good reason that we see leaves as green. It's because they absorb the blue and red light (the blue and red ends of the visible spectrum) for photosynthesis as correctly stated above, but they reflect the green light that they don't use. If they didn't use any visible light, we would see all the leaves as white because they would be reflecting all the visible wavelengths.

So, yes mirrors to reflect light back at your trees will increase the number of blue and red wavelengths (or photon energies if you prefer) that get to your leaves. Also, large sheets of white paper will reflect light at your trees and has the advantage of being cheap, lightweight, flexible so can be curved to roughly focus the light towards a target, and dispersed light so no bright spots etc.

Look up Grow lights, they are approximately magenta/purple to our eyes, = blue+red. These will help your trees get more light energy if they are not getting enough natural light indoors. You can keep them on all night. Trees don't need darkness to sleep ;)

By the way, congratulations on getting my first post on this forum!
 

M. Frary

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The best grow rooms here are all white.
 
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