Thursday 17 March 2011 - 05:19AM
LED Grow Lighting - FACT vs FICTION
“Recent advancements in LED Grow lamps allow production of relatively inexpensive, bright, and long-lasting grow lights that emit only the wavelengths of light corresponding to the absorption peaks of a plant's typical photochemical processes. Compared to other types of grow lights, LEDs are attractive to indoor growers since they consume much less electrical power, do not require ballasts, and produce considerably less heat. This allows LED to be placed closer to the plant canopy than other lights. Also, plants transpire less, as a result of the reduction in heat, and thus the time between watering cycles is longer.”
The above statement is indicative of many Hydroponics retailers and at present the vast majority of Chinese wholesalers promoting LED grow lights as the savoir of the indoor horticultural industry. Sadly, at present, they are very much a misguided group. The problem, as indoors horticultural hobbyists, we all rely on our local grow shop knowledge base, friends and the internet for answers to some if not most of our plant related queries. Most if not all of these sources of information are in accurate and have a tendency to promote a personal interest over a scientifically established one. It is also often published that for vegetative growth, blue LEDs are preferred, where the light has a wavelength somewhere in the mid-400 nm (Nanometers). For growing fruits or flowers, a greater proportion of deep-red LEDs is considered preferable, with light very near 660 nm, the exact number this wavelength being much more critical than for the blue LED. This can be confusing to most growers who do not invest the time into learning all the necessary information to do with this new technology.
For instances we know plant foliage responds well in vegetation to a little extra white light for the full spectrum experience and can produce plants with more fan leaves and a tighter intermodal structure. Additionally for flowering plants have been known to respond to a little UV spectrum light for increased fruiting production. Right at this present moment, not a single LED grow lamp available for the UK market has the suitable lighting spectrum for medium to large-scale hobbyist use, in comparison to standard HID and CFL types of lighting. Mainly due to the PAR (Photosynthetically Active Radiation) sensitivity of these LED’s, hence the need for more research and conclusive scientific testing. Recommendations for optimal LED designs vary widely. According to one source, to maximize plant growth and health using available and affordable LEDs, U.S. patent #6921182 from July 2005 claims that "the proportion of twelve red 660 nm LEDs, plus six orange 612 nm LEDs and one blue 470 nm LED was optimal", such that the ratio of blue light to red & orange light is 6-8%.
A major factor in the slow adoption of this technology is because when compared to HID and CFL lighting LED lamps cannot yet achieve the plant health, strength and most importantly yield that their more energy hungry counterparts can, and for the moment stays as a relatively underground and grass roots technology. One reason for this maybe because early LED grow lamps used hundreds of fractional-watt LEDs and were often not bright enough and/or efficient enough to be effective replacements for HID lamps. Newer advanced LED grow lamps may use high-brightness multiple-watt LEDs, with growing results similar to HID lamps. The company’s producing these lights are at best manufacturing power houses, they do not invest any time in bench marking or testing their products under real world condition, in this case actually growing plants under their LED grow lamps.
But this is set to change, within the last 12 months this technology has come under a lot more attention from bigger name hydroponic lighting manufacturers and is finally gaining the technical expertise and research and development that we have seen in many other outstanding hydroponic and indoor gardening products. Keep checking back for news and detailed test reports for all the major new innovations in Hydroponics and Indoor Horticulture.
