LED grow lights offer many advantages over traditional grow lighting including:

• Less Power
• Low Heat
• Efficiency
• Lower HVAC Costs
• Proximity to Plants
• Spectrum
• Controllability of Spectrum, DImming, Schedules
• WiFi and Remote Operation
• All-in-One Package
• Modularity
• Easy to Install
• Daisy-Chainable
• Different Shapes/Designs
• Different Configurations
• Long Lifetime
• Solid State
• Waterproof and Dustproof
• Recyclable
• Faster FInishing, Better Quality, More Resin, Increased Density
• Return-on-Investment

Let''s take a more in-depth look at these benefits. 

Less power

The primary reason growers chose LEDs over traditional lighting is because of the electricity savings. LED grow lights consume fewer watts to produce about the same amount of usable light as HID bulbs. This is one of the main advantages of growing with LEDs. A grower can use LEDs to deliver more PAR to their plants per watt of electricity.

Keep in mind that some of the wattage that the fixtures draw is not all converted to light. Some of the energy is lost as heat. Furthermore, additional wattage may be used to power cooling fans that blow radiant heat away from the heat sinks.

The average efficient LED grow light draws about 32 watts to cover one sq ft of grow space for flowering plants. Compare this to a typical HID fixture which will ring in at 62.5 watts per square foot (assuming a  4’ x 4’ area, or 16 sq ft coverage area).  

The energy saving that growers can expect from using a very efficient LED grow light, instead of an HID grow light, is around 48%. This percentage may drop to as low as 20% with less efficient LED grow lights. This large energy savings only takes into account the savings growers attain when using LED fixtures. It does not account for other environmental factors where growers can save energy. For example, less ventilation and air conditioning is needed, or can be foregone completely in certain situations depending on the size of the setup and ambient temperatures. Total power savings may rise well above 50% in the best scenarios. 

Light-emitting ceramic fixtures rank near LEDs in terms of wattage required per square foot of grow space. A 315 watt LEC will cover a 3’ x 3’ (9 sq ft) area which equates to 35 watts per sq ft. Growers can expect a 630 watt LEC to effectively illuminate a 4’ x 4’, or even a 5’ x 5’ area with slightly less intensity. Expect about 39 watts per sq ft for 4’ x 4’ coverage and 25 watts per sq ft over a 5’ x 5’ area with

The energy savings is null when comparing LEDs to LECs. For this reason, some growers say light-emitting ceramics pose a threat to LEDs since they are just as energy-efficient as LEDs. But there are many other benefits to LEDs that LECs do not possess. Those advantages make up most of this article.

Furthermore, growers can expect to see a rise in diode efficiency over the next several years, allowing more µmol per watt to be exuded. With a 48% energy savings over traditional grow lighting at this present moment, expect over a 50% energy savings at a lower cost per watt in early 2018 with some of the best LED grow lights.

The increase in diode efficiency is a result of technological innovation and was accurately predicted by Dr. Roland Haitz. Haitz law states that every decade, the cost per unit of useful light falls by a factor of 10, while the amount of light generated per LED package rises by a factor of 20, for a given wavelength. In other words, the cost of manufacturing and purchasing LEDs will decrease significantly, while efficiency will and increase dramatically. Following this trend LED light output will double every 3 years. The trend is driven by advances in semiconductor, material science and optic technology.

Extra energy savings can also be attained since less ventilation and/or air conditioning is required to keep the room at a stable temperature.

Low Heat

Fewer watts means less heat in the grow room. How do watts translate to heat? Well, one watt is equivalent 3.41 BTU/h (British Thermal Unit per Hour) or BTU for short. The more watts that a fixture draws, the more heat it gives off. For comparison, a 300 watt fixture emits 1023 BTU while a 1000 watt fixture emits 3412 BTU’s. Although, this will differ across fixtures and efficiencies. A 1000 watt LED fixture may not exude the same amount of heat as a 1000 watt HID fixture because the LED grow light converts more energy to light and less to heat. 

On average, LEDs provide a lower wattage per square foot than HID fixtures and therefore will push less heat into the surrounding environment. Temperature management is a gorilla that growers must manage. If you don’t tame the gorilla. It will wreak havok on your plants.

Ideal ambient temperatures are critical for plant development and metabolism. High temperatures can stress out your plants which can slow down growth, cause wilting, and even kill them if the temperatures are very high even in a short time span.

An advantage of LEDs is that you can run ambient temperatures higher than you would with traditional lighting since LEDs emit less forward heat and will raise your leaf surface temperature (LST) as much as HID lighting.

Leaf surface temperature is affected by ambient temperature, but is also affected by the invisible longwave radiation, or heat, from the light source. High intensity discharge lights emit excess infrared light at around 820nm that is not used for photosynthesis. The excess heat enters the ambient environment and strikes the leaves.

Unlike HID sources, LED grow lights rarely contain diodes with wavelengths past 730nm. There is only a small amount of heat directed toward the plants that are emitted from the diodes. The rest of the heat is the ambient heat from the panel. Place your hand underneath and LED panel and under a HID fixture to feel the difference in radiant heat. The LED panel’s heat will feel slightly warm, but the HID fixture will feel very warm.

Less efficient spectrums will heat up the leaves more, while more efficient spectrums will lead to a lower LST. Growers who use HID lights will, therefore, need to keep their ambient temperatures cooler to maintain a lower LST. In contrast, LED growers might consider keeping their ambeint temperatures higher, by up to 10° F (as high as 85° F ambeint temperature) to maintain a similar LST as HID growers.

Ideal ambient temperatures are critical for plant development and metabolism. High temperatures can stress out your plants which can slow down growth, cause wilting, and even kill them if the temperatures are very high even in a short time span.

Therefore, the ideal LST is difficult to pinpoint since LST parameters exist in an interdependent system and can depend on plant variety. Perhaps, we will know more about ideal LSTs as research increases.

Efficiency

Light emitting diodes are up to 40%-60% more efficient at converting energy to usable light compared to HID lights. The high-efficiency characteristic of LEDs allows lower energy draw and a low heat signature. LEDs convert about 40%-60%+ of their energy to light, while the other energy is given off as heat. HID bulbs only convert only about 20%-40% of their energy to usable light. What does this mean for the grower? Fewer watts are needed to produce the same amount of light as traditional grow lamps.

Another way to look at efficiency is through PAR efficacy which is typically reported in μmol/J (micromol per Joule). PAR efficacy is more important than using electrical watts to compare grow lights, because a fixture can draw a lot of watts, but that wattage will not directly translate to high useable light. Using wattage to determine the amount of useable light and growing area is a relic from the days of HID.

Why does efficiency matter more than wattage? Consider two fixtures that cost the same amount of money per watt. Fixture ‘A costs $1500, draws 500 watts and emits an average PPF of 700 μmol/s. Fixture B costs $2000, draws 666 watts, and emits an average PPF of 500 μmol/s. One can already start to see the problem—more money is being spent on Fixture B which draws more watts and does not emit as much usable light as Fixture A. The efficiency of Fixture A is 1.4 μmol/J (1 watt = 1 Joule), while the efficiency of Fixture B is only 0.75 μmol/J. Conclusion: Fixture A costs 25% less than Fixture B, emits 28% more light, and is 46% more efficient. Using an LED grow light with high a PAR efficacy will save money on electricity costs.

Lower HVAC costs

Since growers are able to use fewer watts to deliver the same amount of light to their plants, they will have lower capital and operating HVAC costs. Larger grow rooms will require less air conditioning to cool the room. Growers have reported a reduction of 50% in air conditioning costs when switching to LEDs. Not only does the A/C reduction stem from the efficient lighting technology of LEDs, but the fact that growers can run their grow room temperatures up to 10° F warmer when using LED grow lights.

Smaller grows may consider removing air conditioning from their grow setups entirely, since it may be possible to obtain ideal grow temperatures with only using the heat given off from the LEDs grow fixtures.

Furthermore, growers might consider reducing the power needed to run ventilation into and through their grow areas because ambient temperatures are lower when using LED grow lights. This is assuming ventilation is being used to cool the grow area in addition to providing adequate air exchange. A higher rate of air exchange can assist in keeping ambient temperatures cooler if the intake air is cooler than the air inside the grow environment.

Proximity to Plants

LED grow lights can be placed closer to plants than HID lights due to their low heat output—sometimes as close as a few inches! This is advantageous to growers growing in areas limited by height. This feature also allows growers to place the lights closer to plants to ensure optimal light penetration deep into the canopy. Depending on the PPF of the light, placing the fixtures too close can result in light burn so the manufacturer’s recommendations on distance should be followed.

Be aware that the shape and intensity of the fixture will determine how close you can place the unit to your plants. Smaller, “box-shaped” fixtures perform best when placed further above the plant canopy to allow the light to spread before it reaches the plants. Though this will depend on the beam angle of the LEDs in the fixture. A wider beam angle will allow the grower to place the fixture closer to the plants, while a smaller beam angle should be used if the fixture will be placed further from the plants.

Larger, low-profile fixtures such as the NextLight Mega, are designed to be placed close to the plant canopy since the light is spread out over a larger surface area on the panel. The unique design of these fixtures also allows for a evener lighting footprint.

Spectrum

Spectrum is key to maximizing your plant’s potential. While light intensity and duration may be the most important factor in driving photosynthesis, spectrum can affect a plant’s shape as well as flower density, quality, and potency. Certain light wavelengths and wavelength ratios also drive photomorphogenesis effects such as growth rate, stretching and photoperiodism.

Plant growth and response was long limited to the type of lighting whether metal halide, high pressure sodium, or fluorescents. Nowadays, LEDs allow the grower to solicit varying plant responses depending on the intensity and specific wavelengths and wavelength ratios included in the fixture. This is a huge leap in lighting technology.

In general, cooler, or more blue spectrums, are used for vegetative growth, while warmer, more red spectrums, are used for flowering. Full spectrum white-light fixtures have grown in popularity over the last few years as diode efficiency has increased. Some growers use a 3000K, 3500K, or 4000K for full cycle grows depending on the outcome they are looking to obtain or the strain they are growing. 

Whatever the spectrum of the LED grow light, they are a boon compared to the traditional spectrums of HID grow lights. LEDs offer a more full and complete spectrum that benefits plant growth from seed to harvest.

Controllable Spectrum, Dimming, Schedules

An increasing number of manufacturers are incorporating spectrum, dimming, and scheduling (SDS) control into their LED grow lights. A couple examples of this technology include Kind LED K5 series and California Lightworks SolarSystem series.

Spectrum control

Spectral manipulation is from the ability to independently control each the panels spectrum. This is a feature unique to LED grow lights. Traditional grow bulbs beam a single spectrum in which cannot be manipulated. Many LED grow lights contain an array of colors, typically reds, blues and whites, that can be turned on or off in any combination depending on plant’s growth stage or variety/strain.

Dimming control

Many LEDs are dimmable from 1%, up to 100% intensity. Dimming control allows a customizable proportion of wavelengths to be introduced to the plants and can also assist in saving additional energy when full intensity is not required. For example, the grower may choose to dim the blues by 50% while maintaining 100% red and white during flowering. One may also choose to dim all of the color channels to 75% during vegetative growth to reduce total power consumption.

Scheduling/timing

LED grow lights sometimes contain on-board scheduling (or timing), allowing the grower to program their spectrum and dimming schedules directly into the unit. This feature also reduces the need for an external timer since all timing is built into the fixture''s microprocessor. Scheduling allows the grower to manually choose the spectrum and intensity for each hour of the day in a 24 hour period.

With SDS control one can use a single fixture for seedlings, clones, vegetative growth and flowering, while saving energy.

Wifi and Remote Operation

WiFi technology and remote operation of the grow fixtures make the spectrum, dimming, and scheuling possible. Most of these lights connect to a WiFi network in which the grower can use a remote to setup the SDS options. Some lights use a smartphone app to control the fixture’s SDS, while other brands have their own remote or controller.

All-in-One Package

Traditional grow equipment require the grower to purchase a ballast, reflector, and bulbs. In contrast, LED grow fixtures are a single integrated unit.

LED fixtures remove the bulk of an HID grow setup and concentrates it into a slim panel. Unlike HID bulbs, frequent bulb changes are not needed with LED grow lights. Simply hang it, plug it in, and start growing.

HPS vs LED

Power: Ballast | Driver

Light source: HID bulb | LED diodes

Light director: Reflector | LED beam angle/optional secondary optics

Heat management: Ventilation | Heatsinks/cooling fans

Modularity

You might be thinking: “What happens if something breaks in the panel? Do I need an entirely new unit?” In most cases, you don’t. Many LED grow panels are modular and if it is a relatively small problem, parts within the LED fixture can be swapped out with new parts, these parts may include, but are not limited to the PCB boards, lenses, drivers, and fans.

LED panels are currently the most common type of fixture on the market. They usually have a removable back that gives growers access to the inside of the panel if anything needs to be fixed or replaced. Although rare, issues can occur and are fairly easy to fix. It''s usually as simple as disconnecting the faulty piece, whether it is a driver or failed LED board, putting in the new piece and closing the unit back up. The modular system makes the LED light repair a 15-30 minute task.

Problems with non-modular LED grow lights may require the grower to send the fixture back to the manufacturer for repair.

Easy to install

The “all-in-one-package” design of an LED grow light makes installation a whole lot easier for small or large grows.

At a minimum, small to medium-sized grows only require an LED fixture and ventilation/air circulation. Simply plug in the light, hang it up, and ensure adequate airflow and stable temperatures. Growers don’t have to set up a ballast, hang the reflector, and worry as much about the grow space overheating due to the hot temperatures exuded by an HID bulb.

Larger grows have a more complex setup than smaller grows since they must consider the entire lighting system, electrical, HVAC, etc. However, when large farms use LED grow lights, they could install a smaller HVAC system since less cooling equipment is needed due to the lower heatload of LEDs.

Daisy-Chainable

Some LED grow lights allow the grower to daisy-chain the units together to reduce the amount of power cords returning to the socket. In a daisy-chain setup, a grower may have a single light plugged in and then connect several more units to the first unit in series.

Setting up a timer for a single plug is easier than using several times for multiple plugs.

Be aware of overloading the electrical circuit when daisy-chaining lights together. The more watts a unit consumes, fewer fixtures can be daisy-chained together. Typically, the manufacturer will state the maximum number of fixtures that can be connected together in a 120V or 240V setup.

Different Shapes/Designs

LED grow lights come in many sizes and shapes. It is common to find LED lights on the market that cover the square foot equivalents of the following HID bulbs—400 watts, 600 watts, and 1000 watts. Therefore, these LED lights gravitate toward a more square-shaped structure and will cover a 4+ sq ft, 9+ sq ft, and 16+ sq ft area. Two examples of a series with a square footprint includes the Amare SolarEclipse series and Black Dog LED PhytoMAX-2 series.

While most growers will grow in a square space, some growers have a space where they would benefit from a more rectangular lighting footprint. Either, two grow lights with a square footprint can be placed side-by-side or a rectangular-shaped grow light can be used to cover the space. In general, more units is better since it will create a evener lighting footprint.

LEDs can also be used to replace fluorescent T5 tubes with a direct one-to-one replacement where the grower can swap out the tubes for a T5 LED. Instead of 54-watt fluorescent tubes, the fixture’s wattage consumption would be cut in half when retrofitting them with the 24 watt LED tubes.

Furthermore, LED grow light bars, such as the Arize series from GE lighting, are designed for vertical gardening, but make great supplemental lighting lights for hard to light places or may be mounted on shelf bottoms for seedlings and small plants.

Different configurations for different lighting applications

Most LEDs are setup to direct light down into the canopy from an overhead source. This is the most efficient for phtosyntheis since plants absorb light from the top of their leaves. Since LEDs do not get very hot, they can be placed close to plants. Their customizable configuration allows them to be designed for areas that are difficult to illuminate.

Some companies offer LED bar lights that can be hung in conjunction with the main lighting source to target the sides of the grow that may not be receiving adequate light. The bar lights can be placed vertically in the corners of the grow space to increase penetration and open up the canopy as the plant will grow slightly toward the lights. Opening up the canopy can increase light penetration from the light source above, boost photosynthesis during vegetative growth, and deliver more light to smaller flowers that are shaded by the top of the canopy during flowering. 

One of the newest additions to supplementary LED grow lighting includes interlighting modules. These modules are typically 8-ft long (some are 4-ft long) and contain LEDs on both sides of the bar. They are hung horizontally from wires above and placed in the canopy of taller, bushier plants such as cucumber and tomatoes.

We have also seen prototypes of LED light ‘sticks’ that hang vertically and can be placed in the canopy in or between plants. LEDs run along the length of the ‘stick’ and beam light in all directions into the canopy. To picture this, think of placing a fluorescent tube vertically into the canopy. The LED stick works in a similar way.

Long Lifetime

Most LED grow lights on the market contain LEDs that will last around 50,000 hours. Some manufacturers use LEDs that last up to 100,000 hours or more. This is equivalent to almost 10 years of use (at 50,000 hours) or almost 20 years of use (at 100,000 hours), repsectively. Compare this to MH bulbs which last an average of 10,000 hours or HPS bulbs which have a lifespan of 16,000 hours or so.

Due to most LED panel’s modular build, if a grower still had the LED light at the end if its lifespan, they may be able to swap out the old LEDs for new ones and keep on growing.

Solid State lighting

LEDs are considered solid state lighting (SSL). They are not powered by filiments, plasma or gas, but instead are powered by a two-lead semiconducter. The only moving “parts” are the electrons that pass from the n-type to the p-type to create the light that is emitted from the diode.

Because there are no moving parts in an LED, they are subject to external shock with little or no damage to the diodes themselves, unlike other types of lighting such as HID or fluorescent bulbs.

Waterproof and dustproof

Many LED grow lights are rated waterproof and dustproof—typically expressed as the Ingress-Protection code, or IP for short. A lot of fixtures on the market are dusttight and watertight with an IP code of IP65. The first number—6—indicates that the fixture is “dust tight”. The second number—5—states that the fixture can withstand a water projected from 6.3 mm nozel in any direction with no harmful effects. There are some fixtures that are not as watertight as others and may only have a rating of IPX4 or IP63, indicating that they can only be sprayed and splashed with water, respectively.

Most commercial growers prefer waterproof fixtures, where this might not be as large of a concern for the typical home grower.

Recyclable

High-pressure sodium and metal halide bulbs contain mercury and release toxic vapors upon breaking. These bulbs require safe disposal to ensure they do not leach carcinigens into the environment.

On the other hand, LEDs do not contain mercury and are considered safe. This is mostly true—they do not contain mercury, but they are not completely metal-free. A 2010 study by the University of California Irvine, found very-high levels of lead in low-intensity red LEDs and high levels of copper, nickel, and silver in other colors of LEDs, except for in low-intensity yellow. LEDs are solid state lighting and the diodes are typically very small so do not risk breaking. Yet, if the diodes end up in the environment and break down, the metals can leach.

Faster Finishing, Better Quality, More Resin, Increased Density

Many LED growers report faster flower growth and development with some strains finishing up to 5 days sooner when grown with LEDs compated to HPS. Other growers report a higher concentration of trichomes with an excellent terpene profile...one that rivals plants grown with HPS. The higher concentration of terpenes is likely due to the reduced temperatures from LED lights and increased amounts of blue in the spectrum. In addition, flower density is often reported as higher due to the increased blue wavelengths in the spectrum, reducing stretch and creating more compact flowers.

Fast Return on Investment

When do growers see a return on investment (ROI) for their LED grow light installation? There are many factors to consider for ROI that are not related to the direct monetary savings of electricity. For example, consider the cost savings of running less air conditioning due to the lower heatload when using LEDs. Furthermore, growers have reported that their plants are initiating flower development earlier—allowing a quicker turn around—and producing higher quality flowers when grown under LEDs. High-quality flower is worth more than average flower.

Return on investments will vary significantly for growers depending on if they are a small closet grow, a medium sized home grow, or a large commercial farm. 

Additional Benefits

Constant Cycling

Turning on and off traditional bulbs more than a typical number of times can shorten their lifetime significantly. However, LEDs can be cycled on and off without compromising the lifetime of the diode.

Controllable Beam Angle

Optics can be placed over the diodes to narrow the focus and increase light intensity. This is analogous to a HID reflector but better, since the beam angle and intensity can be controlled.

Low Maintenance Costs

LEDs grow lights can last 10 years or more without the need for any maintenance or replacements. Once the fixture is setup, the diodes don’t need to be replaced, unlike HID bulbs which need replacing every several thousand hours.