How to Choose a Quality Indoor LED Grow Light Complete Guide

After years of development, LED lighting is becoming the standard. Costs have come down in recent years, and now their performance equals or betters the traditional solutions.

Older LED technology had difficulty in producing the best light for plant growth. These issues have been largely been solved and it seems their time has come.

Even so, if you’re confused about this modern technology, you aren’t alone! To help out, we’ll go over LEDs and how we got here, and explain how to choose an LED grow light for your goals.

My Top 4 Best LED Grow Lights




MARS HYDRO 400W Full Spectrum Growing Lamp

MARS HYDRO 400W Full Spectrum Growing Lamp


  • All our lights have passed the ETL Certification led grow
  • Full spectrum with IR (730), Superior pure aluminum heat sinks provide great dissipation condition
  • Easily replace 250W HPS/HID/MH Perfect for 70 x 70 x 160cm grow tent 
OUMMET 1000W Plant Growing Lights for Indoor Plants

OUMMET 1000W Plant Growing Lights for Indoor Plants


  • Hi-Efficient Double Chips
  • Silent Cooling System
  • Daisy Chained design
Phlizon 600W LED Plant Grow Light

Phlizon 600W LED Plant Grow Light


  • Led reflector is not heat-resistant
  • LED grow light can replace traditional 400 watt HPS/MH while consuming only 108 watts
  • Perfect for a 2x2ft growing area at 24" height
MARS HYDRO Led Grow Light

MARS HYDRO Led Grow Light

  • 12-band full spectrum with IR to achieve maximum photosynthesis response
  • 600 watts HPS/MH while consuming only 265 watts
  • 3 years authentic warranty


MARS HYDRO 400W Full Spectrum Growing Lamp


MARS HYDRO 400W Full Spectrum Growing Lamp
  • All our lights have passed the ETL Certification led grow
  • Full spectrum with IR (730), Superior pure aluminum heat sinks provide great dissipation condition
  • Easily replace 250W HPS/HID/MH Perfect for 70 x 70 x 160cm grow tent 

OUMMET 1000W Plant Growing Lights for Indoor Plants


OUMMET 1000W Plant Growing Lights for Indoor Plants
  • Hi-Efficient Double Chips
  • Silent Cooling System
  • Daisy Chained design

Phlizon 600W LED Plant Grow Light


Phlizon 600W LED Plant Grow Light
  • Led reflector is not heat-resistant
  • LED grow light can replace traditional 400 watt HPS/MH while consuming only 108 watts
  • Perfect for a 2x2ft growing area at 24" height

MARS HYDRO Led Grow Light

MARS HYDRO Led Grow Light
  • 12-band full spectrum with IR to achieve maximum photosynthesis response
  • 600 watts HPS/MH while consuming only 265 watts
  • 3 years authentic warranty

Introducing the LED

LED stands for Light-Emitting Diode. It’s made of a material that emits light when electrical current passes through it. This is different than older models, which produced light from heating a filament or volume of gas.

A Century of Development

Many ideas were discarded on the way to the traditional light bulb, but one of them eventually became LED technology.

GE filed a patent in 1906 for a tungsten filament that held dominance for the next 75 years. Alternative methods tried, but they fell by the wayside.

The Light Dawns

Other experiments were made with electroluminescence. A study in the 1920’s replicated the phenomenon with different materials, but the light produced was too faint for practical purposes.

The first LED that produced useful light was invented in 1962 by Nick Holonyak. By the end of the ’70s, Monsanto had pioneered consumer LEDs on a large commercial scale and was leading the new market.

Developing Color

Early LEDs emitted light in the red and orange spectrum; green was added in the 1970s. The colors brightened, and in 1994 an ultra-bright blue LED was invented.

By coating these blue diodes with fluorescent phosphors, LEDs could emit bright white light. This advance finally made commercial use practical, and the blue diode’s inventors were awarded the 2014 Nobel Prize.

Soon the big switch to LEDs was underway … and it’s still ongoing.

How do LEDs Work?

Light-emitting Diodes are semiconductors that are charged under a one-way current. The photons are discharged when polarized atoms interact, so that a directed electrical current can produce light upon activation.

Early LEDs were limited to the lower energy wavelengths of reds and oranges, which led to many disappointed plant growers and their rejection of LEDs. New methods to emit the full-color spectrum have turned the picture around.

Modern LEDs can produce the exact lighting effects needed for growing plants, and they can direct their emissions for accurate targeting. Sometimes it does feel like we’re in the space age.

Modern LEDs

Now that blue light diodes exist, manufacturers have two ways to produce white light.

Phosphor Coating – White light can be obtained by shining the blue diode light through white phosphor coating. Though phosphor coating can be economical, it has the problem of not containing the orange spectrum.

RGB Combination – LED’s can be made to emit a cumulative white light by combining diodes that emit light in each of the red, green, and blue spectrums. RGB lighting is preferable for growing, as it can provide the full range of light that plants prefer.

Growing Plants using LEDs

LEDs were not popular among plant-lovers in the early days, because they lacked the blue spectrum and necessary intensity. Now that these hurdles are overcome, LEDs are increasingly favored for grow lights.

It’s important to remember that plants and people don’t perceive the same spectrum. Lighting that is suitable for human eyes is not necessarily good for plant growth, and vice versa.

Plant Light

Each color of light has a specific wavelength, but not every color is equally important for horticulture. Plants don’t typically favor green light, which is reflected instead. In other words, plants look green because they aren’t.

Plants love red and blue light, however, and readily absorb their wavelengths for photosynthesis. The highest energy and shortest wavelengths are colors in the blue and violet ranges. For more information, NASA offers an interesting tour of the light spectrum.

Are Red and Blue Light Enough for Plants?

Red and blue wavelengths are vital for plant growth, but you can achieve even better results by giving them other parts of the spectrum, too. Since natural sunlight contains the complete color spectrum, the closer we keep to Nature the better for our plants.

Some low-cost manufacturers cut costs by only providing red and blue colors in their grow lights. You may get by with this for your plants, but results are better with a fuller spectrum light.

How Effective are LED Grow Lights?

Now that LEDs can be made to emit a wide range of colors, they’ve become more popular for growing plants. The results you can get with newer LED grow lights are impressive, and now equals or surpasses the results you can expect with other light sources.

It’s exciting because the spectrum can be tailored and directed precisely. This opens up new horizons in horticulture technology.

Different Types of Grow Lights

Grow lights come in a variety of color combinations. You can get an LED that emits only the red and blue spectrum to boost these essential colors for a plant. There are even LEDs with only one color, to stimulate plants in specific ways.

Full-cycle LED lights include other colors of the spectrum to provide a more natural light profile. This kind of LED fixture can grow a plant from seed to harvest.

Commercial LED units must have an ETL or UL certification. At the other end of the market, hobbyists can buy DIY LED kits to construct their own optimal designs.

Each of these forms are available in an amazing variety of shapes, including bulbs, grids, bars, and even LEDs that substitute as T5 and T8 fluorescent tubes.

Modern advances have made LED lighting a great choice for common and commercial lighting. Here are some of its advantages:

LED Grow Lights – Pros

  • Low Power Usage – LEDs don’t need much electricity in comparison to older conventional light sources. They generally use about half the electricity of traditional lighting.
  • Miniaturization – LEDs can be very small. The conducting material and electricity needed to stimulate light emission are modest and can operate with little wiring and support. LEDs can be as tiny as 2 millimeters–less than a tenth of an inch.
  • Flexibility – Because of their small size, LEDs can be used creatively in ways never before possible. Another exciting development in semiconductors is the newer OLED technology, which uses organic materials that can be shaped and flexed.
  • Scalability – LEDs can be used to light up a stadium … or to outline your wristwatch’s second hand. Scale changes don’t change an LED’s efficiency or intensity.
  • Low Heat Transfer – LEDs produce much less heat than older lighting, which makes them safer and more effective as grow lights. You can put an LED light almost on top of the plant and not burn the leaves or dry the plant out.
  • Long Life – LEDs are long-lived. They don’t fail, but only gradually dim with age. Where an incandescent light burns for about 1000 hours, LEDs can be expected to last from 30,000 to 50,000 hours or more. Which is serious labor savings, by the way.
  • Durability – LEDs don’t require special filaments or vacuum states, which makes them much more durable than traditional lighting. They are often mounted securely on circuit boards. It pretty much requires a direct impact to affect an LED.
  • Safety – Besides the low heat generated by LEDs, they also don’t emit infrared heat or UV wavelengths that can burn people. They don’t break into shards of jagged glass and don’t have poisonous mercury inside them.
  • Instant Gratification – You can switch on an LED and get on with it, just like with an incandescent bulb. LEDs shine at full power instantly. You don’t have to wait for the ballast to warm the gas up for a few minutes first, as with vapor lighting.
  • Damage-free Switching – You can flip an LED on and off all you want without damaging it or shortening its lifespan. Most traditional lighting, especially fluorescents, will wear out more quickly if turned on and off too often.
  • Adjustability – You can dim an LED easily, and do it with constant, smooth gradation instead of stages. Also, LEDs can be dimmed to just 10% of their full potential; for comparison, fluorescent only dim to 30% of their output.

LED lighting advantages are too great to resist … but there are drawbacks.

LED Grow Lights – Cons

  • Cost – Quality LED grow lights have come down dramatically in price since their early days, but they still aren’t the cheapest lighting. Mass production has reduced the expense and promises to lower it further.

The biggest factor is the rare earth elements that are needed for phosphors, and the extra circuitry involved. Innovation with cheaper materials would change this instantly. The good news is that costs continue to drop, so the expense is becoming less of a problem anyway.

  • Confusion – LED development and commercialization have produced something of a melee in the market, with wildly varying prices, quality, performance, and packaging.

However, the picture is changing. Logical product standards have been created, and more are on their way. The learning curve is flattening.

  • Isolated Wavelengths – The nature of semiconductors is to glow with a uniform color each time it’s activated. Because only one specific wavelength is emitted, LEDs lack the messier but more complete spectrum of heat-generated traditional light.

It is possible to produce multiple colors to generate the wavelengths needed for plant growth. Unfortunately, there is still …

  • Incomplete Labeling – Unfortunately current LED labeling can make it hard to know what you’re getting. Manufacturers don’t generally reveal the exact wavelengths, and no common metric gives us a comparative number to go by.

So, yes, LEDs can produce the optimum light mixture for your plants—but labeling inadequacies mean you have to research more carefully.

  • The Paradox of Energy Savings – One strange effect of cheaper lighting is that it increases consumption. Studies indicate that the likely effect of lower costs will be a net increase in use, as people become accustomed to experiencing an overly-lit world.

No less a personage than the Institute for Environmental Science and Policy’s director Thomas Theis has spoken up: “I am doubtful that we will save any energy by going to LED lights. We’re addicted to light … “if we can consume more, we do.”

How to choose an Indoor LED Grow Light

It’s easy to get lost in the options when buying LEDs, especially when products don’t list the same measurements. Since LEDs work differently than our old bulbs, labeling standards are changing: but they haven’t quite caught up.

To sort it all out, it’s important to understand the different terms manufacturers use. Here are the current measurements:

Wavelengths – Most LED packaging will list the wavelengths it produces.

We reviewed the two main approaches to LED grow lights: to use specific colors for specific results, or else follow an all-natural approach by including multiple colors reproducing the entire spectrum of sunlight.

It can be complicated to find the best light recipe for plants. You have to adjust for phases of leaf growth and fruiting–but, if done correctly, LEDs can deliver results that exceed even that of sunlight.

Watts – The amount of energy a grow light requires is measured in watts.

This was a meaningful metric for traditional incandescent bulbs because turning up the watts made the light proportionately brighter—but that’s not the case with LEDs.

LED’s emissions decay rapidly as the temperature rises. This means LED efficiency usually goes down with higher wattage. Whoa…

The reason is that heat interferes with the semiconductor, to the point a 3-watt LED generally delivers less than a 1-watt fixture. Quality materials and design can help, but the limitation remains.

Lumens – This indicates the quantity of visible light being emitted at one time.

It is a measurement that tells you how much light a fixture puts out, but it doesn’t tell you whether the spectrum it emits is healthy for plants.

Lumens are a better way to measure an LED’s light output than watts, and newer packaging standards make information about lumens widely available. It’s easy to compare.

Here’s a chart showing the standard replacement values based on lumens.

Lux – Lux helps measure the intensity of the source, which has a direct relationship to brightness.

A lux is equal to one lumen of light within one square meter, and measures illuminance, which describes, in effect, how bright the light is to the human eye.

As a more traditional lighting metric, lux describes the quality of light in terms of human use—not plants. For example, lux measurements rate yellow light higher than other wavelengths, because yellow is literally easy on the human eyes. But a plant starves in yellow light.

So be aware that, although this measurement is commonly made available, lux only incidentally relates to horticultural needs.

Horticultural Lighting Metrics

To really compare and understand the LED’s performance as a grow light, you need more information than just watts, lumens and lux values. PAR, PPF, and PPFD can help.

Pro Tip: Manufacturers can focus LED rays to the center point, letting them claim a high rating at the cost of the rest of the grow area. Also, they can fudge the intensity readings by taking them at close distance. Check the labels critically.

PAR – The PAR value, which stands for Photosynthetic Active Radiation, is a metric intended for growing plants (finally!). PAR describes the spectrum of light that plants absorb and utilize for photosynthesis, specifically the wavelengths between 400 to 700 nanometers (nm).

PAR has major weaknesses that render it potentially useless, but at least it’s an attempt to provide information related to horticulture. A step at a time, folks.

The problem with PAR is that it lacks the weighting of light by desirability. Lux weights emissions according to the light that serves human vision, but a PAR doesn’t differentiate on behalf of plant preference.

Also, the PAR spectrum doesn’t include wavelengths outside human perception. Infrared and ultraviolet rays that plants use are excluded from the measurement. PAR isn’t enough.

Photosynthetic Photon Flux (PPF)Another important reading is an LED’s PPF. This measures the amount of PAR light emitted per second. As this indicates the power of a source, you can calculate your the light delivered to the available growing space.

Photosynthetic Photon Flux Density (PPFD)This measures how much PAR light actually gets to the plant. It’s a spot measurement, so it only informs you about a certain point of the illuminated field—but it can be useful to compare with readings taken at the same distance.

Materials & Construction

LED Chip Quality

A lot of engineering goes into an LED chip to make it emit precise wavelengths. The chip contains the semiconductor material and requires precision manufacturing and testing to ensure it is putting out what it says.

Cheaper LEDs skip the fine-tuned manufacturing and go for appearance. You won’t necessarily “see” the difference—but your plants will. That’s why you need to be careful when buying discount LEDs for a grow light.

The Difference between Chip Sets

The original 1962 LED by Nick Holonyak was a Dual In-Line Package (DIP) with a rounded head and two parallel pins on one side. Though still available, the DIP format has been eclipsed by more efficient chipsets.

Surface Mounted Device (SMD) – These LED Chips were the next generation after DIPs. They are smaller and have a flat design, and are usually mounted on a circuit board.

SMDs can emit up to 16 million color wavelengths for versatile and precise spectrums. These efficient chips come in several standard sizes and have a long life, but are subject to issues with heat.

Chip-on-Board (COB)

A newer chipset model is the Chip-on-Board (COB) design. It is a single substrate with nine or more diodes, which are bonded together as a single light panel. This condensed chipset provides wide-angle lighting that is much brighter than older LED chips.

Another big advantage to COB chips is that it generates less heat and has higher thermal resistance, eliminating an obstacle that heat-creating LEDs can have. The high-intensity light possible with COB chips makes them especially suitable as grow lights.

Flip Chip

One of the most recent LED design innovations is the Flip Chip, a patented production process which allows for a flatter profile and higher performance. These chip sets are cooler and brighter than previous LEDs and offer exciting possibilities for grow lights.

Keeping it Cool

Another important factor is how cool the LED stays, as its intensity and efficiency quickly go down as the temperature goes up. Cool operation is a big issue in horticulture because you can gain a lot of light intensity by putting the LED close to the plants.

Some units are designed to run cool using just passive cooling, while others use a built-in fan to keep things humming. This is actually kind of a controversy, if you can believe it. Passive cooling proponents claim a well-designed unit wouldn’t need a fan. They point out that fans can break.

And then fans of fans point to actual performance, which can be as good or better than passively cooled LEDs. Also, many brand warranties don’t cover heat damage, and instead save themselves money by not providing a needed fan. So there.

Getting Started with Indoor LED Grow Lights

First, plan out your goals. Figure out how much space and which plants you intend to grow. Some plants need more light than others, so do your research.

Next, determine the grow area’s dimensions, and calculate the approximate LED source you need. Here’s a convenient Grow Light Coverage Calculator. You can use other calculators, of course, just remember that watts are not the right measurement for LED grow lights. To give you a rough idea of how much space and height you need have a look at our article here.


Breakthroughs in blue light diode technology and intensity allowed LED lighting to suddenly burst upon the consumer scene–and it made possible the creation of new horticultural applications.

We’ve looked at their development and features, and what metrics are used to rate them, and how those measurements can be used to get an idea of the LED’s actual performance. Grow lights are a new way forward for horticulture, and it’s looking very good from here!

Of course, there are some things to remember when buying. Research the specifications and feedback, and look out for manufacturer’s claims that leave room for well-engineered exaggeration.

LED are an exciting innovation that offers amazing potential in grow light performance. We could be seeing a real explosion of light in our future.  If your in the market for an LED Grow light then take a look at this review article.

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