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LED Grow Lights versus HPS Grow Lights; Are LED Grow Lights Better; HID and other Grow Light Comparisons

LED and HPS Grow Lights for Indoor Growing:LEDs

LED technology continues to improve and many indoor growers now contemplate the potential benefits of utilizing LED technology.  Some have used traditional grow lights like HPS systems, and other growers are just beginning.  Both of these groups have similar questions however.  What are the pros and cons associated with the different light types?  More and more users are turning to LED grow light technology over the traditional HPS grow light systems and throughout the rest of this post, I will compare and contrast LED and HPS lights.  LED grow lights are becoming more popular for reasons linked to light effectiveness and efficiency.  I will provide specific examples in the post below.  In the end, my hope is that an indoor grower can utilize this information to better make an informed decision when selecting the specific grow light that will help him or her grow big at home!

LED w Label

LED Technology

Are LED grow lights better than traditional HPS grow lights?  Although HPS grow lights can be used for an entire grow cycle, they pump out a lot of heat and eat up a lot of energy.  There is no doubt, that given the right grow room set-up, HPS grow lights can be very effective, but the grower would need to install proper cooling, ventilation and exhaust systems.  That being said, LED grow lights are also capable of producing positive plant yields as well, and can do so while using less energy and producing less heat and thus the expensive cooling and exhaust systems are not necessary.  It should also be noted here that the circulation of air that is necessary for an HPS system would require the indoor grower to vent the heated air outside routinely.  The exhaust from an HPS set-up is not ideal for the grower that is hoping to grow discretely.

By the way, for those that are a bit confused, an HPS light is a type of HID light.  HID stands for High Intensity Discharge.  HPS stands for High Pressure Sodium and stands for the type of bulb used in a High Intensity Discharge grow light.  Metal Halides are also HID lights.  Metal Halides tend to emit light toward the blue end of the color spectrum and HPS lights emit more of the red color wavelengths.  LED grow lights can be engineered to emit a band, or range, of wavelength colors that will support vegetative and bloom stages.

I have been researching and growing indoors for approximately 15 years.  During this time, I have observed LED grow light technology improve vastly.  The trend of technological innovation is very positive for LED grow lights which leads me to believe that LED grow lights will continue to improve.  The other more traditional grow lights have had their time of innovation, but LED grow light advancements are just beginning.  In general, my experiences have revealed that LED grow lights can be effective and more conducive to indoor growing for several reasons.  These reasons are:

  • type of light being emitted
  • heat production
  • lifespan
  • outcomes and yield
  • versatility
  • cost savings

Below, I will discuss why the above mentioned areas make LED grow lights a smarter choice over HPS or other traditional HID grow lights for the indoor grower.

Sunlight, Artificial Light and Plant Photosynthesis:sun rays and plants

Light from the sun is what sustains all life on our planet.  Plants have evolved to utilize the sunlight by gaining energy from a process called photosynthesis.  This is specifically how light affects plant growth.  Without the light from the sun, plants outdoors would not gain the energy needed for healthy growth.  Sunlight can be divided into respective wavelength colors of red, orange, yellow, green, blue, indigo and violet.  Red and blue light have the most impact on plant growth.  This is why LED technology can be quite effective and efficient for growing plants indoors.  LED grow lights are designed to emit proportions of wavelength colors to which plants respond best.  LED grow lights integrate a high number of red and blue light emitting diodes to act as a catalyst for photosynthesis during plants’ vegetative and flowering grow stages.

LED Grow Lights Emit Specialized Light:wavelength colors

Plants benefit most from light spectra between the wavelengths of 400 and 700 nanometers for photosynthesis and blue and red spectrum wavelengths are absorbed and utilized more by growing plants than other wavelengths. The visible light spectrum consists of light in violet, indigo, blue, green, yellow, orange and red colors. Red and blue light are very important for indoor grow and thus growers need to utilize a light product that emits this type of light effectively. LEDs can be selected that emit just the right light for a given plant type. Blue and red light emitted by LED grow lights can optimize plant photosynthesis.  In HPS lights, their light color falls mostly in the red and orange spectrum due to the inclusion of sodium in the light’s design.

LED Grow Lights are Effective and Efficient at Activating Photosynthesis:par graph

LED grow lights are specifically designed to emit the proper “light recipe” that research shows best supports plant growth.  Photosynthetically Active Radiation (PAR) is used to define the wavelength range between 400 nm to 700 nm. Green plants reflect a greater amount of light in the green range of the light spectrum but absorb a greater amount of light in the blue and red range of the light spectrum. The chloroplasts in the plant take the energy in the absorbable light range (mostly red and blue) and use it to make food. This is known as photosynthesis. LEDs can be more effective at promoting the indoor grow process as they are engineered to emit the red and blue light necessary to produce a high quality plant. LEDs for indoor grow can have targeted wavelength options that can optimize the growing process, and they can do so in an energy efficient manner.  Honing in on the proper light wavelengths necessary for plant photosynthesis is one primary reason that LED grow lights are a smart choice.  HIDs may focus light in just the red or blue range of the light spectrum which is not as effective at acting as a catalyst for proper plant photosynthesis.

Heat Production of LED Grow Lights Versus HIDs:optimal-growth-temperature

Heat production of LED grow lights depends on the operating intensity of the LEDs.  That being said, LED grow lights put off much less heat as the traditional HID counterparts.  Generally, a 3 watt LED will put off more heat than a 1 watt LED, and a 5 watt LED will produce more heat than a 3 watt LED.  All of these LEDs will produce a heat signature that is far less detectable than the heat signature produced by an HID.  I’m currently running 3 watt LEDs for approximately 12 hours, and if I were to touch the lens at the end of this time period, it would feel only warm to the touch.  With HID lights, the indoor grower is always working to counteract the high levels of heat produced by the lights.  This means a lot of extra money spent on ventilation fans,  cooling and exhaust systems.  And as I mentioned earlier, constant exhaust of the grow room air means that it will be much more difficult to grow indoors discreetly.

heat led vs hps

Lifespan:LED vs HID efficiency

I have researched and reviewed many LED grow lights.  It is commonplace for the LEDs to be rated by the manufacturer to last up to 50,000 hours and some LEDs are rated to last up to 100,000 hours!  The math is simple.  Given an average 12 hour running time daily, LED technology rated for 50,000 hours can run for more than eleven years!  The average HPS electric bill savings led vs hpsgrow light is rated to run for approximately 10,000 hours which is a fifth of the time of standard LEDs rated for 50,000 hours.

Outcomes and Yield:

LED grow lights can be engineered to provide the proper diet of light for a specific plant species. LED grow lights can provide the proper blend of the specific light wavelengths that encourages photosynthesis which can ultimately enhance growers’ yields.  Researchers at Michigan State University recently studied differences between several broad spectrum light sources and how their utilization affected plant growth.  The team concluded that incandescent lamps are highly inefficient and are being phased out of production.  They reported that HPS lamps are better than the incandescent lamps regarding energy efficiency, but still waste more energy than LEDs without producing statistically better results.  The research team shared that LED grow lights were likely to consume less energy and deliver the yield hps vs ledspecific light diet a plant needs, all while having a longer life span than the HPS lamps.

Versatility:LED vs HPS versatility

LED grow lights are built efficiently and do not require ballasts.  They are less bulky than standard HID lights and need much less space to function.  HID lights are not only bigger and bulkier, but they need additional space because of the excess heat that they produce.  This requires the indoor grower to have additional space not only for the light system itself, but for the ventilation and exhaust systems needed when growing with HPS grow lights.  LEDs do not need this extra space and are thus more versatile than traditional HID counterparts.

LED associated Cost Savings Versus other Grow Light Systems:LED vs HPS

Although LED grow lights may have a higher initial purchase price, cost savings over time can add up and more than cover the initial purchase price difference.  Cost savings is key as LEDs will expend less energy and heat than traditional HPS grow lights.  The longer rated lifespan of the LEDs is also a cost saver over time.  LED lifespan ratings can be over 5 times as long as HPS lights.  Research has also shown that LEDs run much more efficiently than other lights as well.  Click here for a comparison chart.









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