The Truth About LED Grow Lights
Grow lights have been used for some years now to improve plant growth by mimicking natural sunlight. Over the past couple of years though, LED technology has been getting in on the act and seems to have caused a certain amount of controversy and confusion, with assorted claims and counter claims about how good “LED grow lights really are.
One thing is certain however, and that is the fact that LED lighting is without question the most efficient form of lighting ever invented. Conventional incandescent type lights, such as high intensity discharge (HID) lamps, generate vastly more heat than light per unit of electricity consumed. LED lights lose very little energy as heat and in fact remain only very slightly warm to the touch even during continuous use.
However, what really marks out LED lamps from all other kinds of grow lighting is the ability to very precisely target quite specific wavelengths in the visible light spectrum. Conventional grow lights, by contrast, spread light fairly uniformly over the entire spectrum instead.
This means that not only do traditional grow lights waste electricity (and thus also money and precious resources) generating more heat than light, but most of the actual light they do produce also goes to waste. How so? Because plants absorb the vast majority of the light they need for photosynthesis from just two zones – one in the red part of the spectrum and one in the blue. They neither need, nor benefit from, most of the rest.
These specific features – accurately targeting specific wavelengths of light and using/wasting very little power – quite understandably caught many plant growers attention. Improved performance combined with reduced costs is always going to represent the Holy Grail in any field.
But the good news doesn’t end there. An interesting corollary to giving off virtually no heat is that the lights can be placed much nearer to the plants. Why is this a good thing? In a nutshell, because of the Inverse Square Law of light which states that each time the distance from a light source is cut in half, the amount of light received increases by a factor of four. In other words you can wring even more performance from LED grow lights simply by moving them much closer – not something that is possible with HID lamps since the heat would damage the plants.
LED lighting continues to tick boxes when you consider longevity and maintenance. You should expect to get over 50,000 hours useful life from LED lights – that’s about 10 years continuous (18 hours a day) use. HID bulbs will last maybe a year and you also need to be physically replacing two sets – metal halide to create blue light and high pressure sodium for red.
So one has to wonder why there should be any kind of dispute at all. Surely LED grow lights represent a great step forward in this field? Well, yes actually, they do; but that’s not the problem. The issue is one of perception, or put another way, comparing apples with oranges.
All new technologies attract bootleggers and predators capitalizing on the naive. The fact is that modern, well made units using individual LEDs rated above 1w each will match any HID light – such a device using say 100 LEDs and thus with a total consumption of 100 watts is a good replacement for a 600w HID.
Compare this with a typical “low cost” panel using 225 LEDs but drawing just 14 watts. Sounds great doesn’t it – all those LEDs with very low energy consumption. A quick tap on the calculator however tells you that each LED must therefore be rated at 0.06 of a watt. A so-called “LED grow light” such as this will absolutely not work.
So do LED grow lights really work as well as claimed? Yes and no – it depends what you call an LED grow light. Real ones do, cheap imitations don’t. To make sure that you’re getting a high quality bulb, make sure to shop at a reputable retailer, such as the Lighting Universe.
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