LED Grow Lights From full spectrum LED down to the cheaper more affordable models. LEDs are now being used all over the world to grow marijuana. Recent advances in LED grow light technology have led to more and more growers seeing success, high yields and LED lighting sources are fast growing in popularity. We are here to tell you that growing marijuana with LEDs works. The best models offer results better than HIDs together with huge electrical, management and heat savings. A number of our members in the HTG forum have shifted to growing under LED and are not going back to the old ways of burning electricity with HIDs. What LEDs are available? LEDs pros and cons Brief history of LEDs How are LED colors made? Full spectrum LEDs vs. 3 band, 5 band, 11 band How to make high intensity white LEDs (WLEDs) LED efficiency versus HID lamps High powered LEDs (HPLEDs) – 1W, 2W, 3W & 5W Difference between 1 Watt and 3 Watt LEDs then? IMPORTANT – Advertized Watts vs. actual Watts draw Heat – Thermal management of LED grow lights LED grow light lens – Boost light & direction Most LED grow light components are made in China or another Asian country. The grow lights themselves are then either assembled in China, USA or European counties with varying degrees of materials, skill and quality LEDs. You can have great LEDs, drivers and heat sinks which are poorly assembled. Cheap - Poor spectrum, LEDs and build quality 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. Buy LED Grow Lights today These are trusted partners to delivery Best LED Grow Lights worldwide. Expandable grow tent options, check out KIND LED Grow Lights - 12 Band Spectrum Mid price - Bands of spectrum, fans and reasonable quality 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. High end - Full spectrum, fan-less operation, excellent build quality 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 people 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. 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 hours 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 100 to 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; LEDs powerful enough for lighting big areas like rooms or greenhouses require more precise current and heat management but are now used in some large areas over CFL and HID lighting. Brief history of LEDs How do they work? LED grow lights produce light by passing a current through a semiconductor material. The movement of electrons within the semiconductor releases energy in the form of photons, i.e. 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, namely gallium arsenide (GaAs), gallium antimonide (GaSb), indium phosphide (InP) and silicon-germanium (SiGe) to show infrared emissions at room temperature as firstly observed Rubin Braunstein working with RCA (Radio Corporation America) . Then in 1961 Texas Instruments patented the idea. How are LED colors made? The semiconductor material has a p-n junction which is the interface between the two types of semiconductor materials, n-type and p-type, known as ‘n’ and the ‘p’. This is the active site whereby the electronic action of the LED takes place. The color of the light emitted or its wavelength is dependent on the ‘band gap’ energy of the materials forming the p-n junction. In 1962 -Nick Holonyak Jr., considered by some the father of LEDs, working within General Electric (GE) reported the first visible spectrum LED showing red color. Craford, then graduate student of Holonyak, 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 sued USA farmers, were the first to mass produce visible spectrum LEDs, firstly as indicators, 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, applies similarly 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 As with many plant species, marijuana also has light-mediated development – photomorphogenesis. The blue spectrum stimulates vegetative growth and the yellows, ambers, reds and far-red spectrum stimulates pre-flowering and flowering (reproductive growth). Therefore, growing marijuana to maturity will use the light wavelengths from approximately 420 to 730 nanometres (nm), covering both chlorophyll A and chlorophyll B absorption peaks (Photosynthetically Active Radiation, or PAR for short). LEDs are manufactured using different semiconductor materials to create LEDs which emit light of different wavelengths. Using LED grow lights that emit the proper spectrum is essential to obtaining high yields. In the earlier days of LED grow light technology, your main options were red and blue diodes or more expensive white LEDs. The white LEDs, commonly called full spectrum LEDs, provided a much closer match to the natural spectrum of sunlight (the PAR spectrum) than the individual diodes which emitted light at a single wavelength. As you can see from the table below, there are now many different possible LED diodes that can be produced using different semi-conductor materials. 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 covering much of the visible light spectrum (PAR). 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 LEDs versus the color and wavelength they produce. Many leading LED producers now use an assortment of different diodes in place of white LEDs. These manufacturers state that by choosing individual diodes they can match the PAR spectrum more closely than a white led. White LED lights do have peaks and troughs in their spectrum, as do spectrums composed of individual band diodes. When choosing an LED grow light it is important to consider the spectrum it covers and how closely that spectrum matches the PAR spectrum. There is more good information at LED grow light expert on this. The more closely the LED matches the PAR spectrum the more efficient it is. There is less light that cannot be used by the plants which means less waste. An efficient LED grow light saves on electricity and boosts yields. In addition, less light is lost to heat, which decreases the cooling requirements in the growroom. How to make high intensity white LEDs (WLEDs) 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 index, CRI, 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 spectrum; 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 potential Watts. If you have 100 X 3W LEDs the potential is 300 Watts but the actual draw will be closer to 150 Watts. LEDs are usually driven at anything from between 50% to 65% of their potential. If you run a 1 Watt at 1Watt continuously or a 3W at 3Watt 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. 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. If you are using a smaller LED light (under 700 Watts) look for a model that uses passive cooling through heat sinks. The best thermal management within high powered LEDs uses heat sinks that 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. Because properly designed heat sinks require a large surface area, they are not always the most practical way of cooling large LED grow lights. Some high quality larger lights use a combination of passive heat sinks and fans to efficiently cool their lights. However it is possible to have a fan-less system which if designed well with big fin like heat sinks is optimum as it removes the chance of fans breaking and airflow being required. Thermal management of LEDs is a science in itself. There are a variety of methods, each with its own benefits and drawbacks. Fans add extra moving parts to your system and have the potential to break down if they are poorly made. Choose fans that are rated for a lifetime that exceeds that of the LEDs. Passive cooling systems require airflow and many cannot be mounted to a ceiling. Larger Wattage LEDs that use only passive heat sinks are not always fully cooled. Poorly cooled LEDs degrade quickly from excess heat. Look for a well-built LED grow light that uses high quality components regardless of the cooling technique. 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 indices 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. Actual Watts A 1000 Watt LED does not have the same intensity as a 1000 Watt HID. Whenever you are working with LEDs, you need to consider the Actual Watts, which we discuss in depth here Most LEDs are not named based on their actual Watts, which leads to confusion. If you purchase an 800W LED its actual Watts are will be around 450 or 500. It is a replacement for a 600W HID, but not for an 800W HID. What this means for you: When replacing an HID with an LED, choose the size of the light based on actual Watts. Remember that an LED is more efficient and will replace an HID with higher actual Watts. Currently the only LED grow lights being named for their actual Watts are those from Black Dog. Efficiency and Spectrum LED grow lights are becoming more and more efficient. They can do this in two ways: 1. Intensity of Light: Measured by a PAR meter. 2. Accuracy of Spectrum: The PAR curve shows the wavelengths of light that a plant can use. Any light which hits a plant that is not in these wavelengths is reflected. This reflected light = wasted energy in any LED grow light. What this means for you: The spectrum of an LED grow light should match the PAR spectrum as closely as possible for maximum efficiency. Some manufacturers offer graphs to help you see how their spectrum matches the wavelengths plants use, like this one from Platinum LED. The three lines show the absorption peaks for chlorophyll A, chlorophyll B and carotenoids. The colored peaks show the spectrum that Platinum LED’s lights use. As you can see, they’ve tried to match the absorption peaks for photosynthesis so no light energy is wasted. PPF and PPFD: What Do They Mean Terms like PAR, PPF and PPFD are now commonly referred to by manufacturers and reviewers as important specs of LED light units. But what do they really mean? It’s easy to get confused between what PPF and PPFD are and how they are used when they describe lighting fixtures. Inconsistencies in the industry are widespread, but the reality is not so complex. The definition of PAR, PPF and PPFD: The PAR (Photosynthetically Active Radiation) region is the sum of all the energy that is required to support plant growth and development. It is measured in mmol/m2. PAR levels are at their highest during summer middays and drop down to zero in the night. PPF (Photosynthetic Photon Flux): The total number of photons emitted per second in the lamp’s PAR region. PPF is measured in µMol/S. PPFD (Photosynthetic Photon Flux Density): The total number of photons emitted in the lamp’s PAR Region per m2S. The difference between the two is that PPFD represents a field measurement (in this case the light footprint at a certain distance from the source of light). PPFD is measured in µMol/m2S. Ultimately, the discussion boils down to the terms flux and density. Flux is used to describe the production of power or energy without a spatial correlation. Density on the other hand, applies to the production of power/energy over a specific area that light covers. When reviewing PPFD measurements of a LED lighting fixture, we should always take into account the following data: the height of the lamps at the time of measurement and different spots across the light footprint in order to get our growing priorities straight and avoid inconsistencies. This is precisely why it is tricky to list PPFD measurements when reviewing LED grow lights: it depends on height, grow area dimensions and intensity. How Much PPFD Does Your Grow Really Need Measuring the PPFD of your LED grow light is one of the most important indicators of quality. Light intensity is vital for your plants and you should be aware of the relevant values in the blue (vegetative) and red (flowering) wavelengths to get the best yield. Minimum PPFD Values In order for your plants to reach at least some amount of growth, the minimum PPFD values should be: 255 - 350 μMol/m2/s on a 24/24 light cycle 383 – 520 μMol/m2/s on a 18/24 light cycle 510 – 695 μMol/m2/s on a 12/24 light cycle Medium Anything above 510μMol/m2/s should get you decent results. Be aware though that too much light can be harmful too! Generally, the longer the light cycle=the lower the PPFD value you should aim for. High The optimal PPFD values that you should always aim for for are between 700-1500 μMol/m2/s, provided that you don’t run a 24-hour light cycle. Too High Anything above 1500 μMol/m2/s can be harmful for your plants. Try to maintain the suggested manufacturer distances above the canopy in order to find the sweet spot for your crop and adjust the lights at the slightest sign of light burn. Be aware that PPFD readings will vary greatly depending on the distance of your LED grow lights from the canopy and the different parts of the coverage area. The farther from the center of the light, the more the PPFD measurements will drop. How to use all that information as an indoor grower? Advanced growers can use this information to get the best out of their garden and optimize their plants’ light intake. It is very important to have accurate canopy PPFD values, especially if you use CO2 supplements since the two correlate. So, in order to measure PPFD values you should: Take the PPF value provided by the manufacturer; Reduce it by roughly 15-20% to compensate for lost power; Divide the result by the canopy surface in square meters. That number is the intensity you would expect over that surface area; Use that value to calculate how much CO2 your plants would require in an environment with a relative humidity of about 50-70%. To put it more simply, the PPFD formula is this: (PPF) μMol/S ÷ (grow area) M2 = (PPFD) µMol/M2s Although the above might seem like a treatise on mathematics, it is actually not hard to calculate! PPF and PPFD are useful measurements in LED lighting. However, as with all aspects regarding advanced physics and light engineering, certain inconsistencies occur as the technical details get simplified to reach the average consumer. On the other hand, we exist to help you make smarter decisions! What’s Better than PPFD? When investigating a grow light you want to consider the entire footprint; the larger the footprint, the greater the area that receives considerable amounts of PAR spectrum light. Some manufacturers provide graphs showing the change in the amount of light reaching the plant throughout the footprint of the light, like this great image from California Light Works.