There has been much recent controversy amongst cannabis growers about LED (Light Emitting Diode) grow lights. Just a couple of years ago the thought of growing weed under LED lighting would have been laughable. However, recent advances in LED technology have led to more and more growers claiming success and LED lighting sources are fast growing in popularity. We are here to tell you that growing with LEDs really does work with the best models offering results better than HIDs.
What are LED grow lights?
LED stands for Light Emitting Diode. Light is produced by passing a current through a semi-conductor. There is no filament to burn out and this means that, compared to other light sources, LEDs have an extremely long lifetime with many on the market being rated for 50,000 to 60,000 hours. Compare that to the average HPS grow light bulb lifespan of around 2,400 hours and you can see why LEDs are a better bet long term.
No heat problems
Another happy result of having no filament is that LEDs are much more efficient than other light sources. In a traditional HID up to 95% of energy is wasted as heat radiation, whereas LEDs run relatively cool. With LEDs it is possible to place the light source very close to the plants, usually around 12-18 inches, helping prevent ‘stretch’ and directing the light exactly where it’s needed.
The heat generated in a traditional grow room requires the grower to waste time, space and energy trying to keep it cool and unusual heat signatures have often been cited as the reason why some growing operations are discovered by the authorities. So, with a good LED grow light system you can remove the cost, hassle and noise associated with ventilation systems. Add to this, of course, the fact that inefficient lighting costs money and you can understand why people are migrating to LEDs.
Well manufactured LEDs emit a fraction of the heat when compared to an equivalent HPS lamp. Let’s compare one of the top manufacturers’ LED grow lights versus a 1,000 Watt HPS. Note that ‘BTU’ is a unit of energy and the 1,000W HPS creates approximately 5.4 times more heat than the Super Grow LED – which is simply wasted energy and creates many more problems.
- 8 X Super Grow LEDs (offer the same light as one 1,000 HPS)
- Total Watts 184 (23 Watts each)
- Total ~650 BTU’s of heat
- 1 X 1000W HPS
- Total Watts 1,000
- Total ~3,500 BTU’s of heat
Save electricity, save space
Good broad spectrum LED grow lights run at around 15% to 20% of the electricity cost when compared to an equivalent HID grow light system. Using the example above it is clear to see that running 8 X Super Grow LED units at a total of 184 Watts is a far cheaper solution than running the equivalent light supply from a 1,000 Watt HPS + 150 Watt ballast. Reducing energy costs and consumption is not only greener but saves growers money. In addition to this, growers save space with LEDs as they can hold the light far closer, at around 12-18 inches, to the plants and remove ballasts, fans and ventilation systems from the room, too.
Broad spectrum, 3 band, 5 band, 11 wavelengths etc
So LED systems are cheaper and cooler to run, but do they provide the right kind of light?
The light spectrum is measured in nanometres (nm) as shown in the image above from infrared through the visible light spectrum to ultraviolet light.
Cannabis requires the blue spectrum for vegetative growth and the yellows, ambers, reds and far-red spectrum for pre-flowering and flowering. Growing marijuana will use the light from approximately 420 through to 730 nanometres (nm) and everything in between. Lights that offer this range will cover both the ‘chlorophyll A’ and ‘chlorophyll B’ absorption frequencies, as well as additional photosynthesis production stages which is known as the Photosynthetically Active Range, or PAR for short.
For the marijuana grower one of the beauties of LED lighting is that good models operate right across the spectrum so you can use the same light from seed germination through to flowering. Look for LED grow lights that operate across a broad frequency from at least 420 nm through to 730 nm and everything in between. LED grow light manufacturers have to specifically mix the colors within their product and some often miss portions of the required spectrum.
There are many commercially available LED units that have spectra specifically balanced LEDs for the grow room. This is generally achieved by using a mix of red and blue lights, but several suppliers are now including LEDs that provide light in the green, amber and far-red ranges.
LED grow lights are often marketed as 3 band, 5 band, 11 wavelengths etc, these are not usually broad spectrum products. These products operate in some but not all of the spectrums required for a successful, fast, big yield crop. Quite often LED light companies are reselling someone else’s product configuration and they simply don’t know what they are selling.
1W, 2W, 3W and 5W LEDs
LEDs are produced en-mass and then samples are tested to see what current they can cope with. Some of the 1 Watt LEDs can tolerate twice or three times the current and so they are marketed as 2W or 3W LEDs. These are the same LEDs as the 1W but with more current being pushed through them. There is a cost to this, these LEDs may fail quicker and produce more heat, requiring cooling methods such as fans and heat pipes to be incorporated. Well constructed 1W versions with no fans are the best bet for a successful, heat free long term operation. However, if you must purchase a unit with fans in it, make sure the fans are rated for a lifetime that exceeds that of the LEDs.
LED grow light lens
There are many types of lenses and reflectors available to harness the LED’s output and direct it where it will do the grower the most good. A simple, well-designed reflector is usually suitable to do the job, but Total Internal Reflective (TIR) lenses more fully and accurately collect and guide the light.
Make sure you choose a reflector or lens product with an output that meets your needs. An LED’s light output is usually a cone with a 160 degree angle. Some LED grow lights have no lenses and obviously, these are a waste of valuable light, and your money. Some products have 120 degree lenses and any lens is better than no lens. However, too wide a lens spreads the luminous intensity over too great an area, either providing too little power to your plants, too wide a coverage area (and wasted light that doesn’t fall on your plants), or both.
Narrowing the lens or reflector increases the power delivered to your plants significantly, up to 400-500%, but narrows the effective coverage area. A good trade-off for both problems is to use a medium output angle, from 60-90 degrees. The grow light manufacturer should provide effective coverage charts for their products and some will even perform photometry evaluations for your specific grow area, telling you exactly where to place your light(s) for maximum effect.
The commercial sector is really leading the way with LED lighting, making available a huge selection of lighting units. Although this is to be welcomed, the down side of it is that there are also many substandard products available that are not up to scratch and that will not produce the plentiful yields growers have become accustomed to with HIDs.
If you do decide to invest in some LED grow lights it is important that you buy from a reputable source and be sure it’s somewhere that you can ask questions about the spectrum and light intensity of the unit. We can highly recommend working with Super Grow LED, they offer the best broad spectrum LED grow lights on the market. They are not just resellers, they are the manufacturers, they don’t sell junk, and they designed their products with the benefit of decades of LED lighting experience.
Big yields are obtainable using good LED grow lights which is noted by some of the leading Dutch growers moving to purely LED based systems. One thing is for sure though, the technology is here right now and in a world where energy efficiency, heat reduction, space saving and sustainability is vital, LED grow light systems have a bright future for indoor marijuana cultivation.
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