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.
- 1 My Top 4 Best LED Grow Lights
- 2 Introducing the LED
- 3 How do LEDs Work?
- 4 Growing Plants using LEDs
- 5 How to choose an Indoor LED Grow Light
- 5.1 Wavelengths – Most LED packaging will list the wavelengths it produces.
- 5.2 Watts – The amount of energy a grow light requires is measured in watts.
- 5.3 Lumens – This indicates the quantity of visible light being emitted at one time.
- 5.4 Lux – Lux helps measure the intensity of the source, which has a direct relationship to brightness.
- 6 Horticultural Lighting Metrics
- 7 Materials & Construction
- 8 Getting Started with Indoor LED Grow Lights
- 9 Summary
My Top 4 Best LED Grow Lights
OUR #1 CHOICE
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.
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.
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.
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
LED lighting advantages are too great to resist … but there are drawbacks.
LED Grow Lights – Cons
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.
However, the picture is changing. Logical product standards have been created, and more are on their way. The learning curve is flattening.
It is possible to produce multiple colors to generate the wavelengths needed for plant growth. Unfortunately, there is still …
So, yes, LEDs can produce the optimum light mixture for your plants—but labeling inadequacies mean you have to research more carefully.
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.
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.
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.
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.
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