There has been much recent controversy among cannabis growers about LED 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 marijuana with LEDs really does work with the best models offering results better than HIDs and huge electrical, management and heat savings.
LED Topics Discussed
- LED pros and cons
- Brief history of LEDs
- A brief history of LEDs
- How are LED colors made?
- You need white LEDs!
- Full spectrum LEDs vs. 3 band, 5 band, 11 band etc
- LED efficiency vs. HID lamps
- High powered LEDs (HPLEDs) – 1W, 2W, 3W & 5W
- Difference between 1Watt and 3Watt LEDs?
- Advertized Watts vs. actual Watts drawn.
- Heat – Thermal management of LED grow lights
- LED grow light lens – Boost light & direction
- 2013 Full spectrum LED grow lights compared
- The Future
LEDs pros and cons
- LEDs have far lower energy consumption running at approximately 60% of an equivalent HID;
- There is no filament to burn so LEDs have longer bulb times of 50,000 to 60,000 versus HIDs which start dropping output considerable at 2,000 to 3,000 hours;
- LEDs are smaller and faster to emit light and are physically more robust so they relatively shock resistant being solid state components;
- LEDs’ offer far less heat output, in fact the good ones run pretty much ‘cold to touch’ while HIDs run very hot. LEDs reduce your fire risk considerably;
- LEDs can focus their light output with the use of lenses rather than disperse the light like HIDs that require reflectors;
- Precise current (power) management is required with LEDs when compared to HIDs. However, LEDs have the power management built in while the HID lamps rely on external ballasts which also add another 150 Watts of power consumption;
- LEDs are more expensive to start a grow with when compared to HID but they are cheaper over the long term;
- LEDs are instant on and instant off, they do not need to ‘warm up’ like HID lamps;
- LEDs can be dimmed also if required;
- LEDs are safe, classed as ‘Class 1 LED product’ as they do not contain mercury like compact fluorescents.
Brief history of LEDs
How do they work? LED grow lights produce light by passing a current through a semiconductor material, this in turns moves electrons which creates light.
LEDs once just came red in color, they were the little low lights in the corner of every TV. These days LEDs have advanced massively, they are now available across the spectrum from ultraviolet through the visible right into infrared wavelengths with very high light output.
The first observation of ‘electroluminescence’ was in 1907 by a British experimenter from Marconi Labs named H. J. Round. Then twenty years later, way back in 1927 a Russian named Oldeg Vladimirovich Losev created the first LED but no practical use for it was found. It took until 1955 for semiconductor alloys, known collectively as GaAs such as gallium antimonide (GaSb), indium phosphide (InP) and silicon-germanium (SiGe) to show infrared emissions at room temperature found by Braunstein working with RCA) Radio Corporation America. Then in 1961 Texas Instruments patented the idea.
How are LED colors made?
The semiconducting material has a ‘p-n junction’ which is the section or boundary between the two types of semiconductor materials, known as ‘n’ and the ‘p’. This is the active zone whereby the electronic action of the site takes place. The color of the light emitted or its wavelength is dependent on the ‘band gap’ energy of the ‘p’ and ‘n’ materials. If you want more detail than that, first of all I am impressed secondly, please go ahead and hit Google, it goes deeper…
- In 1962 the ‘grandfather’ of LEDs Mr Holonyak working within General Electric (GE) reported the first visible spectrum red LED. Holonyak then created the first yellow LEDs and improved the overall brightness of his red and orange LEDs tenfold in 1972;
- The Monsanto corporation, yes the seed guys who sue USA farmers, were the first to mass produce visible spectrum LEDs and that began in 1968;
- We had the first high powered blue LED (not the first blue) created by Shuji Nakamura of the Nichia Corporation in 1994 which was based on the semiconductor alloy InGaN or Indium gallium nitrite, your new word for the day?
- This quickly led to the development of the first white LED using Yttrium aluminium garnet or ‘YAG’, which is a phosphor coating to mix ‘down-converted’ yellow light with blue which produces a visible white light;
- Moore’s law which saw the doubling of chip performance every 18 months to two years, It’s a similar game within the LED industry with a doubling in performance ever 36 months since the late 1960’s due to the improvements in semiconductor and optics.
Full spectrum LEDs vs. 3 band, 5 band, 11 band
Marijuana requires the blue spectrum for vegetative growth and the yellows, ambers, reds and far-red spectrum for pre-flowering and flowering. Growing marijuana to maturity will use the light wavelengths from approximately 420 through to 730 nanometres (nm) and everything in between. Lights that offer this wavelength range will also cover both the ‘chlorophyll A’ and ‘chlorophyll B’ absorption peaks, as well as additional photosynthesis production stages which are known as the Photosynthetically Active Range, or PAR for short.
Plant absorption peaks - Specifically chlorophyll A and chlorophyll b
We now know that LEDs are manufactured using different semiconductor materials known as ‘GaAs’ (gallium arsenide) to create LEDs of different wavelengths.
What wavelength or spectrum your LED grow lights offer your marijuana is of paramount importance to your yield. The most expensive LEDs are white, offering a broad spectrum of light like the sun cover much of the visible light spectrum. You need white LEDs! If you see an LED grow light with just red and blue lights you are not going to achieve a high quality grow at all as the white LEDs are so much closer to mimicking the sun. The table below outlines the different GaAs versus the color and wavelength they produce.
Methods of producing a high intensity white LEDs or WLEDs for short.
- Use a single LED that emits three primary colors of red, green and blue and mix the colors perfectly to form a white light. These are known as ‘multi-color white LEDs’ or ‘RGB LEDs’ and are more complex to manufacture than the phosphorus type explained below. Multi-color LEDs are at the forefront of LED development because with the right tweaking they can offer nearly any color light we want by mixing primary colors. These are the best type of white LEDs;
- Or use a phosphor based semiconductor material to convert a blue or even a UV light into the broad or full spectrum white light your plants require. These WLEDs are known as; phosphors based white LEDs which are also the easiest to manufacture and therefore the cheapest to buy;
- There is a third method of making white LED grow lights using zinc selenide (ZnSE) but this is in its early stages.
The key difference between WLEDs is how solid their color stability, color rendering and luminous efficiency are key. Color rendering is CRI and basically means how faithfully the color is produced, you may know the term from using Photoshop. While luminous efficiency is discussed later on. If your LED grow light is constructed using LEDs from brand name suppliers such as Cree or Bridgelux, then these issues will be minimized and cause little affect. It is far easier to get good solid color rendering and luminous efficiency with the multi-color or RGB white LEDs.
- 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 then white, ambers and far-red ranges so that they cover the entire PAR zone;
- When you see LED grow lights advertized as 3, 5, 6, 11 or 12 band LEDs this means they offer a spectrum with gaps, maybe something like this: 440nm, 470nm, 525nm, 640nm, 660nm, 740nm. So there will be peaks and troughs in the spectrum produced rather than one continuous full or broad spectrum. These ‘6, 11, 12 etc band’ products operate in some but not all of the spectrum required for a successful, fast, big yield crop. These are not full spectrum grow lights.
- Quite often LED grow light companies are reselling someone else’s product configuration and they simply don’t know what LEDs are mounted in the system;
Did you know that LEDs are now available is very short wavelengths with near UV 375-395 nanometres and more expensive models that achieve wavelengths closer to 240 nm. The absolute wavelength depths of LEDs are known as ‘deep UV’ with labs using diamond to produce 235 nm, boron nitride at 215 and aluminium nitride right down at 210 nm.
LED efficiency versus HID lamps
LEDs are ‘luminous efficient’, which means they produce visible light very efficiently from electricity. For example in 2002 Lumileds manufactured a 5W LED with a luminous efficacy of 18 – 22 lumens per Watt, compare that to the traditional incandescent bulb which at around 80 Watts offers 15 lumens per Watt (lm/Watt). Nichia released a white LED 140 lm/W in 2010. Since then Cree have increased that right up to 254 lumens per Watt at a color temperature of 4,408 K (Kelvin) using the Cree XLamp® which uses silicon carbide technology and runs at 350 mA. Note these figures are in controlled labs and are only the chip, so in real life after the LED has its plastic shell and is mounted these figures will be much lower but they are still better than the HPS lamps with standard HPS lamps running at approximately 100 lm/Watt.
These days, good LED grow lights will save a grower around 50% off their electrical bills. Growing with 2 x 250W (true Watts drawn not potential draw) equals a total power bill of 500 Watts per hour. This setup will offer better but comparable growing to a 1000 Watt HID (HPS or MH) which also requires a 150 Watt ballast. So when you include the ballast and potential ventilation system the savings are more like 60% or more.
High powered LEDs (HPLEDs) – 1W, 2W, 3W & 5W
Normal LEDs used in electronics consume a tiny 30-60 milliwatts (mW) of power at very low amperage; note the word ‘milli’ in there. However high power LEDs running at between 500 milliwatts to over 500 Watts (Yes! Think industrial lighting) are driven from 100’s of mA (milliamps) to over an Ampere. In 1993 the first highly bright blue LEDs were manufactured by the Nichia company and were based on silicon carbide. It wasn’t until 1999 that Philips Lumileds introduced the first 1 Watt LEDs to the market in far larger semiconductor die sizes.
So what is the difference between 1Watt and 3Watt LEDs then?
The 1W and the 3W can tolerate running at a range of power outputs up to and over there named Wattage. So a 3W LED can run at say 1W but it will also be able to run at say 4W too. Why, well it’s because the names given to these LEDs (1W, 3W, 5W) are only ever a guide as to the power possibilities of the LED. However a 3W LED is built on a larger semiconductor die size when compared to a 1W LED so it is built to run at higher Watts, this why it is named a 3Watt LED.
IMPORTANT – Advertized Watts vs. actual Watts draw.
All LED grow lights run well below their named or marketed levels, usually at anything from between 50% to 65% of their potential. If you run a 1 Watt at 1Watt continuously or a 3W at 3W you have a greater chance of color shift and will also cut its life (hours) down considerably, just as you would running a car at high revs all the time.
Let’s get this straight; don’t be fooled into thinking that just because your LED grow light has 150 x 1W LEDs it as an output of 150 Watts, no, it does not, well you hope it doesn’t as the bulb time will be severely limited if you power it at full capacity at all times. Your LED grow light will have an output closer to 55% to 65% of its full capacity; the same concept applies to all LED grow light diodes.
Again, if you see a light advertised as 450 Watts using 150 x 3W LEDs its actual draw will be more like 250 Watts. You can work out the actual output or draw of any LED grow light using the Volts, Amps Watts calculator. If the company selling the lights does not advertise the Volts and Amps then you have to wonder why and assume they are run at 60% of capacity. We have compared a couple of popular LED grow light models further down this page on their actual draw versus their advertised.
Heat – Thermal management of LED grow lights
Another happy result of LEDs having no filament is that they are far more efficient than other light sources and LEDs produce far less heat. With traditional HID’s, up to 95% of energy is wasted as heat or radiation, whereas LEDs run relatively cool they do still produce some heat. That heat difference means HIDs should be placed two or three feet above the plant canopy while LEDs can be placed extremely close, usually around 12-18 inches, helping prevent ‘stretch’ and directing the light exactly where it’s needed.
Even though LEDs are far more energy efficient and waste a lot less heat than HIDs there are still heat issues associated when running high powered LEDs. LEDs are cool to touch mainly because they do not produce heat in the form of infrared (IR) radiation. The higher the Watts the less energy efficient they become because they turn more and more electricity into heat which is wasteful and needs management.
Where does the heat come from? The heat originates at the semiconductors p-n junction due to its slight inefficiencies when electrical activity is not turned into light. The p–n junction in turn heats the soldering point and that heats the metal core printed circuit board (MCPCB) which then needs to be directed into a heat sink so it dissipates into the atmosphere.
Heat sink thermal management of high-powered LEDs
The three areas focused on for heat transfer are convection; which uses a moving fluid such as water or air to cool the device, conduction; whereby heat is transferred from one solid to another until there is no more and the last is radiation but that isn’t used with LEDs.
The best LEDs use heat sinks to control heat. The heat sink medium provides a path from the LED to the medium which dissipates the heat. The best thermal management within high powered LEDs use heat sinks and they include materials such as aluminium, copper, thermoplastics and at the high end of the cost scale, graphite. The heat sink material needs to incorporate a large enough surface area to work so this is why you see the classic ‘fins’ shape layered next to each other to the top of some high end LED grow lights.
Thermal management of LEDs is a science in its self, there are a multitude of methods with the best not using fans (convection) at all. When you include a fan in an LED grow light to manage heat issues it introduces a moving part. Moving parts have a habit of breaking down long before your LEDs fade. However, if you must purchase a unit with fans in it, make sure the LED has a long warranty and the fans are rated for a lifetime that exceeds that of the LEDs.
LED grow light lens – Boost light & direction
LEDs only look like their finished product when the ‘die’ or ‘chip’ is set or encapsulated in a resin or plastic which is known as potting. This plastic shell helps out in many ways. It holds the very delicate system together, mounting the LED is made far easier in products and it acts as a lens or refractive intermediary to boost the light from the semiconductor. As you can imagine there are a lot of different methods of potting these chips to make LEDs – some cheap and some expensive which result in different light output.
Light extraction of grow light LEDs is just as important as the semiconductor materials being used. Most materials have very high refractive indicies so that light is reflected back and out of the LED.
- 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 products have 120 degree lenses but we find a LED lens with an angle of 90 degrees is just about perfect at directing light deep into the plants. However, too wide a lens spreads the luminous intensity over too great an area, it wastes light, either providing too little power to your plants, too wide a coverage area or both. Some LED grow lights have no lenses and obviously, these are a waste of valuable light, and your money;
- 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.
How are LEDs made?
2013 Full spectrum LED grow lights compared
There are numerous types of LED grow lights on the market with the vast majority coming out China. When you are looking to purchase your own set of grow lights there are three distinct markets to choose from:
a) Cheap - UFO type LEDs from many online sources and of course eBay. They may quote all kinds of huge Watts or ‘full spectrum’ but when you see big red and big blue LEDs in a cheap looking plastic housing you know this is the bottom end of the market. You will not be getting top shelf LEDs and results / yield will be drastically affected. We just don’t recommend these products at all. You are far better off buying a HPS/MH system and deal with the added electricity costs and ventilation issues.
b) Mid price - These usually look more the part with better housing, higher quality LEDs that may even include brands like Epistar and Bridgelux. In variably though these will not be full spectrum LED grow lights they will be 6, 8, 11 or 12 band models. These bands will cover sections (bands) of the whole PAR spectrum but will miss chunks here and there. The sun doesn’t miss any of the spectrum required to grow and flower plants correctly so why would your plants react to their full potential under them? They don’t. Mid price larger models will incorporate fans for cooling.
c) Higher end - These are more often the full spectrum models that cover approximately 420 to 750 nanometres, the PAR range. They include expensive white LEDs and in photos you will see some LEDs look like they are ‘dead’ – not true these are emitting in the far-red portion of the spectrum which is 710 to 850 nanometres, dimly visible to some peoples eyes. Look for high end components such as brand name LEDs from Epistar, Bridgelux or Cree. Thermal engineering is a key to design with the best being fan-less. LED grow lights that are high Watt and fan-less are designed well because they have dissipated the heat created by the LEDs perfectly using rapid heat sink materials. Then there are self protecting power supplies, UV protected and angled TIR lenses and not to mention the warranty, two years is not enough. LED grow lights with these features offer excellent results with thick and juicy buds.
Full spectrum LEDs that operate throughout the 400-450 to 700-750 nm light spectrum are perfect to use from seed to harvest. They carry the blue light for vegging and the yellow, amber, orange and reds for flowering. You can replace a 1000 Watt HPS for around 500 Watts of LED (500W true power not claimed) which would yield around 600 grams of dried buds.
Good fan-less LEDs run 1W or 3W LEDs and these lights can be situated mere inches above the canopy, however setting them at around 18 inches allows the lights to disperse the light over a larger area and gets better results.
The four LED grow light systems outlined below are all claimed to be full spectrum and are all around the 250W mark, taking into account the true Wattage rather than the total Wattage of the bulbs as explained earlier.
Of the four, both the Black Dog BD-240-U and Super Grow’s new Spectrum King™ (SK450) can claim to be truly full spectrum, while the Hydro Grow’s Penetrator 168X Pro and Prosource’s Illuminator Pro target specific wavelengths. Some growers say all you need for a short season flowering crop is blue, red, plus small amount of UV and infra red. Others state that it’s best to mimic nature as closely as possible. It seems that the manufacturers are equally split into camps. Certainly, for a wide range of plants, a true full spectrum system is best.
The main difference between the Black Dog and the other systems, which may explain the lower price, is that the LEDs don’t have lenses or reflectors to collect and guide the light – reducing concentrated over the plants with a strong percentage of the light missing its’ target. To compensate, the lights need to be placed closer to the plants, reducing the effective growing area.
The Penetrator 168X Pro uses lenses that provide a beam angle of 60 degrees, which creates a more intense light over a relatively small area. The manufacturers also claim that their X2 lens system further increases the intensity, so more light will reach the bottom of the plants. One feature unique to the Penetrator 168X Pro is the switchable power settings from 0.5W to 1W to 3W. This is slightly misleading, as the unit is only designed to deliver just over 1.5W per LED at full power. Hydro Grow attempts to provide PAR data for the Penetrator 168X but if you visit their website you’ll see that is a graphical form that’s very difficult to interpret.
ProSource have opted for variable angled beams. This means, for example, that some may be set at 60 degrees, some at 90 degrees, and others at 120 degrees. The claim here is that this produces more illumination to the tops and the bottoms of the plants. This might allow for a slightly wider growing area but it’s questionable whether it has any real advantage single fixed angle beam.
Super Grow have opted for 90 degree lenses on the Spectrum King™ (SK450) and this is perhaps the best compromise for maximising the cropping area while maintaining a reasonably high light intensity. On a cost per sq ft of harvest area, the Spectrum King 450 works out best value of the four lighting systems. If you need a larger growing area and are after a slightly more intense light, two SK450s can be bolted together. Super Grow’s spectral distribution data for this twin light arrangement is a very close match to natural daylight.
2013 LED grow light conclusion
Based on the specifications, the Super Grow Spectrum King™ (SK450) looks like the best value. It produces a continuous spectral distribution that is close to daylight, it uses name brand LEDs, does not require an internal fan due to the impressive thermal management design and comes with 90 degree TIR lenses to concentrate the light on the plants.
Where space is limited or if you only want to grow a few plants, The Black Dog BD-240-U is worth considering, with what looks like a good spectral distribution and plenty of light.
If all you have space for is a single row of plants, due to its long, narrow geometry, the Penetrator 168X could be the ideal solution, but you may find it hard to justify the high set up cost.
The Illuminator Pro Hybrid 350W appears expensive with nothing special to offer. It has a fairly limited spectral distribution and we were slightly put off by the manufacturer not being open about true wattage. The spectral distribution may also be a bit restrictive, depending on what you want to grow.
Black Dog BD-240-U
|Hydro Grow Penetrator 168X Pro||Prosource Illuminator Pro Hybrid 350W||Super Grow LED Spectrum King™ (SK450)|
|Cost per Watt ||$2.70||$4.35||$4.54||$3.59|
|Dimensions||13.5”x13.5”x 4”||19″x13 x3″||6”x 48″x3”||22”x14”x6|
|Lenses angled||n/a||60 degrees||Variable||90 degrees|
|Harvest area ||6.25 sq ft||7.5 sq ft||16 sq ft||16 sq ft|
|Setup cost per sq ft||$103.20||$153.20||$74.94||$56.18|
|Spectrum coverage||full spectrum ||5 band ||red, infra red, and blue||full spectrum |
|Warranty||Unknown||3 years||3 years||5 years|
- Advertised price as of August 2013. Shipping not included.
- Based on maximum input wattage, which may be less than the total wattage of the bulbs. For example, the Hydro Grow Penetrator 168X Pro has 168 x 3W bulbs but it is not possible for them all to run at full capacity.
- Harvest area for flowering plants. For young plants or leaf crops, harvest area may be 15 to 30% larger.
- Manufacturer claims that their Phyto-genesis Spectrum™ utilizes hundreds of beneficial light waves that include multiple wavelengths targeting crucial absorption peaks in the red, orange, violet, and blue spectrum, as well as IR and UV.
- Actual wavelengths not stated.
- Full spectrum output is augmented by additional discrete LEDs to further enhance the chlorophyll red absorption peaks.
The commercial sector is really leading the way with LED grow 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. They give the good LED grow lights a bad name.
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 full spectrum LED grow lights we have seen anywhere. 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 noted by some of the leading Dutch growers who have already moved away from HID 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.