How good is LED lighting for use in growing food plants.

"Light Emitting Diodes (LED)
While NASA and many universities are actively engaged in studying this exciting new technology for use in growing plants, many people are reporting very disappointing results when using most of the LED plant grow lights currently being marketed to home gardeners today. We have tested many versions in our store and have reached the conclusion that the only ones that come close to even considering are priced in the $2,000.00 range, and in our opinion there are much better performing conventional technologies available today that outperform LED's and do so at a much lower cost."

http://www.homeharvest.com/whichgrowlightisrightforme.htm

Indoor growing has been around for years. I have an indoor plant propagator, and can start as many as 2000 plants.

In years past, I've run an indoor growing program, and had fresh vegetables and fruit year round.

It can be actually very simple and low tech, and you don't have to spend a lot of money.

"... and can start as many as 2000 plants."

Oh? What kind of plants? "Fruit and vegetables?" Uh huh.

Oh, you would think that. Go wash your brain out with soap.

Those days are long over.

Besides, my kids would kill me.

"Go wash your brain out with soap."

That's the kind of reception I get for having an open mind? Hmph!

(here, have a peach)

There are limited spectrum issues, and the addition of phosphors to broaden the emitted spectrum are being used but ....

NASA report here (page 19 of original, 26 of PDF):

http://asgsb.indstate.edu/bulletins/v19n2/v19n2.pdf

Heres another:http://www.msfc.nasa.gov/news/news/photos/2000/photos00-336.htm

(Not everyone thinks of NASA as comprehensive, authoritative and respected, but they do underwrite a lot of research...)

This link looks more like quackery than science,

http://ultraledlights.com/full_spectrum_grow_light.htm

But for those folks who wanttheir vegetable growing to be confidential, these good folks have thought of that too:

WE RESPECT YOUR PRIVACY !!! IF YOU WANT, WE CAN SHIP YOUR ORDER TO A UPS DEPOT NEAR YOU WHERE YOU CAN PICK IT UP. JUST ASK US OR ENTER IT IN THE COMMENTS SECTION OF THE SHOPPING CART.

http://www.led-grow-master.com/LEDGardenerNov.html

Amsterdam is where I would look for this technology to be in 'commercial' use.

milo

Plants use chlorophyll a and b for photosynthesis, a absorbs a maximum at two points 430 and 662 nm, and b at 632 and 475, more or less which is whey plants look green the chlorophy a, b does not grab that.

So if LEDs were made that gave those two peaks, like grow lights, they would be as good or better, depending on the intensity.

Bear in mind that LEDs are about 40% more efficient than fluorescents, both are 200-300 % more efficient than incamdescents(7%)

http://www.emc.maricopa.edu/faculty/farabee/BIOBK/BioBookPS.html

The maximums are good to know, but how broad is the range where they are absorbing 95%, or 90% ? Think of it as the natural "rainy day" discount . Also, what about the ideal amount of light, since over the year in every season, the length of the daylight is changing, at least at US latitudes. Is there much research (NASA or other) on this ? If so, where ?

We actually sell a High Power LED bar that contains 12 red, 12 blue, and 12 green 1 watt high power LED's.

This unit has a built in program, that cycles through every possible color every minute.

For those of you that didn't know this, equal combinations of red, blue, and green light, produce white light.

Therefore, introducing this multicolor light over any growing plant, will greatly increase the photosynthesis and will germinate, produce root growth, and leaves and strong stems on any growing plant.

The limited growth LED's one mentioned in this thread are regular 5mm normal LED's without much luminous effect, yet they are expensive because of who you buy them from.

Most "LED" Grow lights on the market are mostly red led, with a small amount of blue led. So, maybe that is another reason they are not working well.

The natural light of the Sun, at it's brightest point, during the day, say at 2:00pm on a cloudy day, is measured at 5000 degrees Kelvin.

Therefore, because you cannot get a better "Grow Light" than the sun, just duplicate that spectrum, in great intensity, and you will grow plants indoors quite successfully.

Sincerely,

Donald

"This unit has a built in program, that cycles through every possible color every minute."

Ooops! That statement is true only if you define "color" as what you perceive as color. Clearly, it does not cycle through every possible wavelength. You might as well have your plants in front of a color TV set.

My cat watches TV and has grown very fat meanwhile. Does this count?

If your cat is a female it's quite possible otherwise stop feeding him/her so much.

"Does it count?"

You never know! I was told once that 'if you cannot look after your dog then you cannot look after your woman'.

So, the choice is yours how you want people to judge you just by looking at your pet. If they see your cat's looking other than an anorexic then they might judge positively, simple as that.

This not true. The three leds are monocolor, and the duty cycle of what the a and b chlorophyl receives will determine the effective illumination.

Remember bright sunlight that plants use to max efficiency is 10,000 foot candles.

The gro-lux lamps we have used for years are far lower than that and are a poor substitute for full sunlight, but they are OK on plants that are shade adapted to lesser light intensity and a lower rate of synthesis.

All I know is that this light has 12 red, 12 green, and 12 blue High power LED and it is Bright, not dim like the 5mm type grow lights.

Like I said, it automatically cycles (by fading each color), and produces hundreds of different colors by it self.

It also has a simple DMX512 console where (If you know how), you can stop it, or several of these wired together on any color spectrum you desire.

Yes, the three LEDS are moncolor, IF they were only lighting by theirself, but the combination of the three main colors produces blended light, Not monocolor, on the product being illuminated.

That's all I know about it..

Donald

If you look at color theory you find that the eye hav different receptors and the brain processes these inputs to provide us with all manner of intermediate colors.

The plant must have light of the frequency it needs for chlorophyl a and b to gather that energy to perform photosynthesis. It has no way to process mixed colors into what it needs. In addition, infra red lacks the energy for critical energy processes in chlorophyl a and b. Some bacteria in the sea use ir, but land plants never evolved to use ir, why should they? No driving force, but in the sea ir penetrates better

"but in the sea, ir penetrates better."

Beg to disagree, if that were true, we could see red things under water- which we can't unless we bring light.

Actually visible red is absorbed by about 100 times more factor than Blue (its absorption coefficient is 0.01 or 10^-2 while blue is 10^-4), as you can see on the graph, that makes infrared (peak at 10^4th is IR, to the right is near infrared and f=then far infrared.) even more favorably absorbed, thus less 'penetrating"

milo

Longer wavelengths (the IR end of things) diffract more and scatter more quickly than the shorter wavelength blues and violets....this is why the red dissapears so much quicker as you go deeper underwater.

Sorry to burst your bubble but RGB lighting does not produce white light. I produces a blend of red green and blue light that our eyes perceive as white. Run your RGB light through a prism or diffraction grating and the three primary colors are separated. True white light has the full visible light spectrum at equal intensity.

Different plants require different wavelengths of light as well as amounts. I don't know if any-one is researching this topic, but it is certainly one worthy of serious research, as we could feed the world if they can be used - we already can, of course, but we are too disorganised to effect it yet, but this technique would make it that much easier. CJ

In most situations, I would think that the inefficiency of incandescent lights wouldn't be a problem for growing plants as the waste energy helps heat things up and improve growing.

Ideally, you would want to concentrate all energy only in the bands the plants use and LED's have the potential to enable us to do that.

If required, heating is more efficiently provided by CO2 emitting fuels as the CO2 increases plant growth significantly. Nurseries have taken advantage of this for years.

I agree completely. Most greenhouses and indoor growing occur where it's a bit too cool for the plants and where the growing season/day is not long enough. The heat plays a big part in the seeds germinating and deciding it's spring and time to grow.

While science seems to have identified the wavelengths required, perhaps areas like infra red are more important than we have previously thought.

This was sparked when I read http://www.popsci.com.au/scitech/article/2009-02/infrared-could-restore-eyesight

If IR can spring this sort of surprise, what other unsuspected benefits will we find in the plant world. Most of the energy in sunlight is, in fact in the near IR, not the visible spectrum.

I am writing hear from a position of profound ignorance of the subject. This doesn't usually stop me having an opinion

Search "UFO led" on Ebay.