A friend of mine recently got his state-approved license to grow, and I've suddenly found myself obsessed with learning how to grow MJ. I also used to live near a friend that had a garden, where I learned quite a bit. These are a few things I'm working on designing:

-- LED Lighting (home-made, very specific design)
-- Aeroponic/Hydroponic rubbermaid tub system (home-made, self-contained w/ sprinklers & reservoir, air-stone in res.)
-- High-speed ventilation, with pauses for CO2 (all through home-made carbon filters)
-- Aeroponic Cloning setup (15-site, RO Water, 100-200ppm, )
-- All of this built into a 6'Wx7'Hx30"D Locking Cabinet... that looks like a bedroom wardrobe cabinet. (really excited about this one)

This thread is dedicated to light & the potential of LEDs. I'm a bit of a geek when it comes to electronics, and I got drawn in by this project. I've learned incredible things about light in the past few weeks... light intensity for humans vs. light intensity for plants, which colors plants use most during different stages of their life, lux/lumens/mcd still doesn't make perfect sense (it will someday). I've looked at the Pros & Cons of different types of lighting systems - efficiency, light output, heat, light beam angle (more important than you think).

First, I'd like to say this: I'm not impressed, or even marginally satisfied with any of the LED grow lights on the market. There are a few main reasons why, and we'll get to those as you read on. For now, let's look at some of the positive aspects of LEDs.

Low Power Consumption. This is usually the first reason someone goes to LEDs, so let's get this topic right out in the open. The debate is this: To get LEDs to grow the same yield (quantity & quality) as a 600-1000W HID bulb, would you need so many LEDs that you were no longer saving power?

After exhaustive studying on converting candelas to lumens and how it sounds like it's not really possible, I found a chart that helped me out immensely. It has everything I needed to know.

----{See Image - Candles per Light.jpg}----

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Candles per Light.jpg (128.6 KB, 157 views)

The LED setup I've been working on gives off about 9,000 candelas (cd). They run so cool, they can be touching the plants, though I'll probably give them a protective glass screen 1" away. Being one inch from the top of the plant means none of the light will be wasted. One very renowned grower says that every 12" your plant is from the bulb, you lose 50% of your light intensity, which is directly correlated to your yield. Move the light from 12" to 0", double the effectiveness of the light. This chart says that my LED panel will be very similar intensity to a 400W HID bulb at 14". You wouldn't want an HID bulb much closer unless you have a good light ventilation system. The test LED setup I'm looking at would use 200W. 200W Custom LEDs @ 1" is about equal to 400W HID @ 14". I might also add side-strips of LEDs to stimulate the growth of the lower foliage... stronger light, still under 300W.

Here's the bonus: These calculations are based on how the human eye sees light. Red or Blue LEDs that are putting out the same amount of light as "White" LEDs have a lower mcd (millicandela, 1/1000 cd) rating than the white. This is because the human eye sees Green and Yellow the BRIGHTEST, which are the two colors plants use the LEAST. With very few green/yellow LEDs, the room will appear darker to us (lower rating) and brighter to the plants... that's great!

----{See Image - Plant Light Curve.jpg}----

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Plant Light Curve.jpg (57.8 KB, 39 views)

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In this chart, we can compare the two. The solitary white line is the "Plant Sensitivity Curve," and the colored in area is what the human eye sees.

The current LED grow lights on the market talk about this, but it doesn't appear most of them have done any research. They say, "The plants only use the blue & red spectrum," or "Blue is used more during vegetative growth and Red is used more during flowering." Both of these statements are somewhat true, but severely misled.

Plants use all colors. Think of the light color as availability of nutrients. In their vegetative cycle, plants use more light from purple to blue to almost green. "Blue Spectrum" doesn't do it justice. In the flower cycle, plants use more light from the yellow-orange-red-deep red spectrum. "Red Spectrum" is quite an understatement. Notice I said the plants use "more" of specific colors during certain cycles. The plant still uses all colors in all cycles... it just uses some colors more during different stages. This chart shows what enzymes and plant organs use different colors of light. The left side is purple through blue, then green and yellow are the low center area, and orange-red-deep red are the right.

----{See Image - PAR action spectrum.gif}----

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PAR action spectrum.gif (66.8 KB, 33 views)

The sun emits its light throughout the whole spectrum. CFLs can be "cool white" or "warm white," which both have quite a bit of green/yellow (bright to us, dark to plants). Some people prefer to veg in Metal Halide (MH) and flower in High Pressure Sodium (HPS) because they are broad spectrum lights that have a bit more intensity in a particular color spectrum.

LEDs give us freedom from these limited bulb types by allowing us to specifically adjust the intensity of light in every specific color of the spectrum. If I get access to a color intensity meter, I can fine tune the light output to match any curve I want. That'll be incredibly useful. It'd take quite a bit of research, but I could even design separate veg & flower LED panels.

There are some pitfalls to LEDs, so let's not ignore them. With the right care in design, we can overcome the negatives and accentuate the positives. The light that is emitted from LEDs is very directional. If you look up LED Grows on YouTube, you'll see many "test setups" where the light looks like a straight beam, lighting up a small bright dot on the leaves of the plants. Also notice that most of these test grows exhibit signs of stretching - tall skinny plants caused by being too far away from the light. Not all LEDs are this narrow. All LEDs I'm looking at are at least a 30 degree beam, some much bigger.

Another concern with narrow beam angles is not enough cross-lighting in the plants. Plants in grow rooms with more than one light will benefit from both lights, not just the one directly overhead. If the LEDs are directional this could be greatly reduced. Less light on the under-foliage means light, airy buds (or none at all). OK for hash, but you'd like it to be better. This concern is why I mentioned the possibility of some LED light strips running up and down the walls to get more light down under the canopy.

The setup I'm looking at creating has 2,304 LEDs in a 1ftx1ft square. That's a ton of LEDs. Each one of them has to be individually pressed into a breadboard, I have to design an exact pattern to follow that gets the proper voltage to LEDs that run on different voltages, maximizes the space on the board, properly spreads the different colors evenly throughout the light, and I want it to look pretty decent. A step up from ghetto, at least. If they work as well as I hope they will, maybe I'll start having them manufactured.

More info as it comes... subscribe to the thread if you want the updates. Hopefully, there will be a test grow in the near future. The friend that just got his gardening license is interested, so I'm hoping to create a test cabinet. Exciting!

I just realized... if I make the lighting specific to what the plant actually wants, I'll have the closest thing out there to a PAR/PUR light. Freakin' badass.

What're everybody's thoughts on the setup?

So, I've been playing with the design more, and here's what I've come up with (see picture). It has three curves on it to compare: Plant Sensitivity Curve, Human Eye Sensitivity, and the light output by the current LED setup I've created.

This is my variation of the plant light curve, combining each of the previously mentioned charts, in a way. The human eye curve was taken from another picture. The LED light output comes from an Excel spreadsheet, where I can increase or decrease the number of LEDs for different wavelengths, and it automatically tells me the change in price, watts, amps, etc... and it updates the chart!

If the color measurements don't make sense, they're in nanometers (nm). 470=blue, 550=green, 600=orange, 640=red. The x-axis is the color spectrum from violet/blue to orange/red.

Attached Images

LED Light Chart.jpg (41.4 KB, 39 views)

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Cuttings have been taken and put in my DIY aero cloners... Grow journal coming soon.
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Since plants use Green/Yellow light the least, we're not wasting energy by producing those colors of light. However, we've broadened our color usage in the blue and red spectrums (both grossly under-stated), helping all of the cell organs and enzymes get the exact type of light they want.

You may notice that I didn't provide much light in the deep blue (430) and deep red (680) colors... simply put, those LEDs are much more expensive. I'm sure that after 2 or 3 harvests, you'd get your money back for having spent the extra money. The question is, would it be more beneficial to spend $130 for a few 680nm LEDs or $130 to double all of the other LEDs?

Either way, my friend's grow room is coming together, so I'll probably be placing orders soon... I'm excited to start building it!

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Cuttings have been taken and put in my DIY aero cloners... Grow journal coming soon.
-=[{Everything I write in these forums is entirely fictional.}]=-

YAY for LED DIY

Good research.

I like the idea of exactly matching the generic plant par curve... very good optimization idea, but as you noted, not practical.

Nice profile-boob for the human eye curve

First: step up to a much more powerful one watt led or 5 watt led package, something from a reputable player like cree or phillips lumileds. They're products are worlds beyond the 5 mm leds that stick in breadboards. Think surface mount - These type actually need heatsinks, and not because they're less effecient.

If you insist, for ease, on sticking with a breadboard, you will still have to get a real heatsink on there... you know how many watts you're going to be pushing, Its going to make heat.


...you ideally want as much power as possible to drive sensimilla, for which a decent red is definitely the favored wavelength.

... so to answere your question MORE RED, and cfls for blue veg and filling in for the absent spectrums.

But really, I saw a guy literally fill up a bread board somewhere on this board with dees... and it got very, (ineffeciently) hot.

you really should rethink what your light source is,

...figure out whats current in the industry.

And damn this shit is expensive!

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For this setup, most are 3mm through-hole LEDs, one type is 5mm. The efficiency of each LED seems to be about equal, so I based light output on the input wattage (for the chart). This trial run will be built on breadboards... if it seems to be exactly what the plants want, I'd consider selling them in the future (probably after a little more research).

I've figured out the specific layout on the breadboards, but I don't really want to go into that detail here... this thread is more about light concept and if we can more efficiently provide the exact colors of light the plants need most. Let's hope we can.

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Cuttings have been taken and put in my DIY aero cloners... Grow journal coming soon.
-=[{Everything I write in these forums is entirely fictional.}]=-