So i was researching what the best type of light for my girls would be. I came across an article in high times on the subject with a very interesting graph. It shows the relative efficiency of photosynthesis across the visible spectrum on top of the relative spectrum of sunlight. What appears to be happening is that the amount of energy the plant is receiving throughout the visible spectrum is much more evenly distributed than most people think. Since there is more energy available in the middle of the sunlight spectrum, the plant can be less efficient and still receive an equal amount of energy as the ends of the spectrum where there is less energy but the plant is more efficient. If the graph and my interpretation of it are correct it would imply that white light, (ideally LEDs) with the highest output in the middle of the spectrum, would be the most beneficial light for a healthy indoor plant. There is more available energy in the red spectrum so it would be beneficial to supplement with LEDs above 600nm. Share your thoughts if you have any Link to article - http://www.hightimes.com/read/nicos-nuggets-light-and-your-indoor-grow
You may be on to something here. A few months ago, I began following a journal where white LEDs were being used. The topic intrigued me because up until then, it seemed like the only LEDs that were being used to grow with were the ones with the pinkish purple lights that focused on blue and red wavelengths. What I saw in the following weeks of his journal was shocking and impressive. When was the last time you saw a plant take a "Pepsi Challenge"? Post# 52 on Weed Dude's Journal found here: http://forum.grasscity.com/indoor-grow-journals/1317804-white-light-led-revolution.html Long story short, I took a leap of faith and decided to try them out for myself. I started with a few panels to see how they compared to what I was currently using. And if this picture is any indication of how healthy plans grow under these white LEDs... The plants in my garden responded very well to the new lights. I will be adding more as the harvests come along. The plants know what is good for them. In my experience, they definitely grow better under the white LEDs supporting your hypothesis. "One must be sane to think clearly, but one can think deeply and be quite insane." -PG
Thanks for the feedback PG, those are some seriously impressive plants! Your girls look stunning too! Is that a scrog setup you're using or just topping/training? Also, what lights are you currently using? I've looked into adding supplemental white LEDs to my current 600w MH/HPS. For the time being I can't beat the price and performance of HIDs. Im sure in the coming years the LED market will become affordable and efficient enough to compete, but for now it is still HID. Anyway i found that Cree makes COB (chip on board) LEDs that can handle 50-100 Watts on one chip. It is essentially a bunch of individual high power LEDs laid out on a single heat sink plate. You can buy the COB LEDs for $30-50 online and power them with a $20 LED power supply, stick the COB on a heatsink and you have a 50W White LED at 110 LM/Watt for around $60. Not bad for LED grow lights, and you can expand as much as you want. Check out this build guide if it sounds interesting. http://www.rollitup.org/t/diy-led-grow-lights-with-cree-cxa3070-cobs-and-cpu-coolers.805681/
Very cool DIY! Tempting... I like to make stuff. The panel looks like one of those R/C multi-copters. The plants were "Fimmed", defoliated and LSTed with a modified tomato cage to get them to look like that. If you look closely, you can see the stumps of the petioles near the lower nodes. I was surprised at how fast they grew under the LEDs because up until then, I vegged under T5HOs. Defoliating quickly became a chore with the LEDs. The strain in the pic is Kalichakra from Mandala Seeds and has some Sativa traits as you can see. At the time I took the picture, they were under only two SolarSPEC 150w panels. I added a third panel to help with flowering. -PG
that graph is not accurate. here's a graph at the bottom of this page, McCree et al the black line on the graphs is absorptance in C3 plants. here's a little data to check out, the second graph you see is the graph to go by when looking into what plants need. http://dutchgardenint.com/docs/Utah-State-University_Lighting-Study.pdf