Understanding LED Grow Lights

These lights have taken indoor growing to new heights, being the most game-changing invention since the Carbon Filter.
If you’re an indoor grower, beginner, or master grower, this article is for you ! 

L.E.D. stands for Light Emitting Diodes, and like LED's this article will shed some light.. on the subject.

Enough with the jokes already, let me take you on a journey through a very brief history of LED’s, LED Grow Light Fixtures, the main types of LED Grow Lights, and how to effectively choose LED lighting for your situation. 

A Brief History of LED’s

LED’s first appeared in 1962 with scientist Nic Holonyak Jr. who created the LED while trying to make a laser. Generations of researchers worldwide have built and added to this tech. The technology continues to advance today, driven by ambitious companies squeezing every last lumen possible from each watt of power. 

Today, horticultural LED technology continues to progress with LED industry leaders such as OSRAM, Bridgelux and Samsung doing their best to improve efficiency and reliability. 

Samsung’s LM301B and LM301H (H for Horticulture) are the most sought after LED diodes, taking their places in the most powerful and efficient LED fixtures that we offer. OSRAM’s Red Light LED’s complement the White coloured LM301 chips, making a great light spectrum to grow with.
This technology doesn’t stop with just the PAR (Photosynthetic Active Radiation) range of light, the new generation of LED lights include specialty LED diodes emitting light such as Ultraviolet (UV) and Far and Deep Red 


LED Grow Light Fixtures

LED Grow Lights, in particular, started to enter the growing scene in the early 2010s. My first LED light came from a West Coast grow shop in 2012, and I have followed the progression of these fantastic lights ever since.

In the early days of LED grow lights, there was Red and Blue lights, together combined they’re affectionately called the “Blurple”. These lights outputted about 3 watts each at full bore and often burned out prematurely. These discrete diodes output a specific colour of light and when combined together, they provide a pretty good fit to a plant’s range of preferred light spectrum called the PAR range. 

Photosynthetically Active Radiation (PAR) is light between 400 and 700 nanometers, which is the range of light colours that plants use for photosynthesis. There are benefits to light outside this range, such as UV and Far Red (more on this later).


LED Grow Light Fixtures

Glossary of LED Terminology


  • Diodes - A semiconductor which creates light as electricity passes through it.
  • DLI - Daily Light Integral, the amount of PAR light reaching you plants in it’s daily cycle. 
  • µmol/s - Pronounced Micromole, this unit represents the photons of visible light emitted. 
  • PPF - Photosynthetic Photon Flux is the micromoles of light per second, or the brightness.
  • PPF Efficacy  - Amount of light photons created per joule of energy.
  • PAR - Photosynthetically Active Radiation, light that plants can use between 400nm and 700nm. 
  • PPFD - Photosynthetic Photon Flux Density amount of light reaching an area per second Spectrum - The range of colours comprising light, from UV to Deep Red


LED Lights

Types of LED Grow Lights :

Today you have the choice of the discrete “blurple” LED, Chip on Board (COB), or the newest Quantum Boards and Light Bars featuring OSRAM or Samsung diodes. Depending on your situation, we have a light for you. 


Discrete Diode Panels and “Blurple” LED Lights


A little over a decade ago, some LED lights started showing up on the market  were built specifically for growing. These lights typically use a collection of Bridgelux or Epistar diodes to create a spectrum of light to grow and flower plants indoors. Each small LED light on the panel has a specific colour.

The designers of these light panels could make a colourful cocktail of lights specifically tuned to the type of light that the plant needs to grow. The red, white, and blue LEDs are often used on some of the entry-level lights, resulting in the famous “blurple” colour.  

Blurple lights were first style on the market commercially, so this technology has had a long time to grow and mature. Today, the Black Dog LED company has mastered using this discrete LED technology, and continue to improve their offerings. They use 5w Cree and Osram diodes, brands that are known for quality and reliability. Black Dog LED creates extremely powerful lights that their engineers have crafted to get the perfect spectrum of light; their lights are world-class. They were the first to start using UV and Infrared light to speed up harvests and to improve plant quality.


 LED Lights

Chip on Board (COB) LED Lights

COB lights represented a big leap forward from discrete diodes which once ruled the LED grow light market, offering improved efficiency and reliability. Shaped like an egg yolk or perhaps a miniature Sun, this style of LED packs many tiny LED diodes into what looks like a single source of light. These lights offer a range of light colour or spectrum such as warm lights (2700k to 3000k) resembling HPS light, neutral light(3000k to 4000k) resembling daylight, or cool blue light (6500K+) similar to HID lighting.

With these COB LEDs, you can choose the cooler light colours (4000k to 6500k+) for the vegetative phase of growth, while the warmer lights are great for flowering (2700k to 4000k). I’m most fond of 3500k COB’s myself as a seed to harvest light. Having experimented with many COBs, a 3500k neutral White is pleasant to work under as you can see the plants in a natural light, which is helpful for monitoring plant health.

Quantum Boards and Light Bars


These incredible lights can replace a 1000w HPS light while using much less power !

Today’s LED Grow market has embraced Quantum and Light Bar style lights. These lights are shaped in a bar or board form and contain incredibly high quality and powerful LED lights. This style of light spreads the diodes over the surface of the light structure giving a more even spread of light and passive dissipation of heat for fanless and silent operation. These quiet lights get an even spread over your canopy, allowing for consistent growth and less hot spots.

Light Bar LEDs are very similar, but arrange the LED’s in a more linear fashion rather than the rectangular Quantum Boards, spreading the lights over the growing space. Today’s strip shaped Light Bar lights and Quantum Boards feature white, far Red, infrared, and UV light. Rayonled, and Spider Farmer great examples of brands using efficient LED lights using the Samsung LM301 diodes combined with OSRAM Deep Red LEDs to great effect. 





LED Grow Light
Light Bars

Rayonled’s newest light is the GLMF720W, a 720 watt grow light which would be perfect for a 5x5 area. Employing Samsung’s top-shelf LM301H diodes, this powerful light puts out a spectrum light that others try hard to emulate. This model is essentially the 640 watt light on steroids. The extra 80 watts it has for you are in the form of UV and Deep Red spectrum bars, powered independently of the super-efficient Samsung diodes. Rayonled’s light puts out over 2000 micromoles of light, so this Canadian light may soon be the standard to which all others are measured. 

It’s also got a RJ14 port which allows this light to be connected to a controller unit for performing tasks like timing, light ramp up and down (sunrise and sunset simulation), even dimming based on the temperature of the grow area. Using controllers means less time that you have to be taking care of the garden; a controller will do this work for you.

Here’s what Mike from Rayonled had to say about combining Deep Red and Far Red spectrums of light in plant growth:

Here’s what Mike from Rayonled had to say about combining Deep Red and Far Red spectrums of light in plant growth:


The addition of Far Red and Deep Red equals a greater rate of photosynthesis than the sum of the individual parts. When simultaneously exposed to both wavelengths (660nm and 730nm), the rate of photosynthesis increases by 30%.
graph logo
LED Grow Lights

Blue (450nm), Deep Red (660nm) and Far Red (730nm) are the most efficient LEDs for horticulture (which we peak in all 3 of these wavelengths) 

Deep Red light speeds up the rate of Photosynthesis allowing the plant to make better use of all the photons that are falling on the plant’s leaves. 

Lighting Requirements and How to Maximize Your Results

For best results in your grow, consider having anywhere from 25 to 40 watts of LED lights per square foot. If you’re going to the high end of that wattage range, consider adding a source of CO2 which will allow your plants to make full use of all that light. Raising your ambient CO2 level while your plants are quickly growing in late veg and in bloom will be of great benefit to plant growth and the resulting yields. Please take a look at our Passive CO2 sources, and our Active CO2 Sources.

LED lights are highly efficient, and there are some ways to get even more out of your LED lights, ensuring the most efficient use of your investment in a light fixture. Consider growing inside a Grow Tent. It’s reflective walls will ensure that the light that isn’t directly reaching your plants will be reflected onto them. Grow tents also help improve canopy penetration, making sure that the light is getting down deep into the plants, and not just lighting the growing tops.

Author’s Note :

“Pairing the cutting edge of efficient LED tech with today’s up and coming environmental controllers will allow growers to harness the power of these specific LED spectrums to maximise the genetic potential of their plants.

The field of Photomorphology is advancing because of growers like you out there sharing your experiences with LED technologies. Keep Growing and sharing your experiences. Consider this my public thank you to everyone who shares their reviews with us, people who post in forums, and in groups where growers risk their crops to try new things. I’d like to also say a special thank you to Shane from MIGRO, who tests these and many other LED lights on his Youtube Channel. 

We’re on the verge of being able to maximise yield and quality for whatever you’re growing. Imagine the possibility of emulating the sun. We’re not that far off in LED tech.”


1 comment

Bob Eckess

Bob Eckess

Good Article!
I’ve been using LED’s for a couple of years.
Crops are good but could be better.
Thinking of purchasing a LED rack instead of my single lights now that I have built a grow room.
I’ll look at your recommendations.
I’m in Canada.
Thanks again.
Bob Eckess

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