When building your own grow room, one of the most important factors to consider is your light source. Options include HID, fluorescent, and LED lights. But which is the best choice and why? In this article, we’ll take a look at the development of grow lights so you can better understand the outdated ideas surrounding some lights, and what the future holds for indoor gardening.
Grow Lights: Both New and Old
Although the concept of indoor gardening is new enough that even our parents scoff at the idea of artificial lighting being any substitute for good old fashioned sunlight, scientists and innovators have been using artificial lights to grow plants for over 150 years!
Going all the way back to 1861, when a biologist and politician named Hervé Mangon published a paper in France on the production of green matter in plants under the influence of electric light, keen minds have seen the potential of electrically induced light in promoting plant growth. In 1868, russian professor Andrei Faminstyn proved that plants could produce CO2 and starch under electric lights.
In general, the early years of artificial light production centered around three types of lights:
- incandescent lights (as made famous- but definitely NOT invented by- one Thomas Edison)
- open-arc lights (two electrodes, usually carbon, having an arc of electricity pas between them)
- gas discharge lights (exciting noble gases in controlled containers)
Although the gas-discharge light was the first invented by a long time (Earliest nascent work with igniting noble gases in controlled environments dates to the 1670s!), the open-arc lamp was first invented in 1802, and the first incandescent light was invented in 1835, it wasn’t until 1880, when Thomas Edison received his patent for the incandescent light bulb and electric lighting became commercially and domestically available that interest in the various possibilities of artificial light sparked the general imagination.
Fluorescent Grow Lights
Fluorescent lights are sometimes called the first generation of grow lights, as they were the first lights produced with emissions capable of sustaining plant life.
Fluorescence is the emission of light by a substance when exposed to external radiation. In a fluorescent lamp, this is achieved by passing an electrical arc through inert gases like argon and mercury, which releases UV radiation after being electrified. The UV radiation hits the edge of the lamp, which is coated in phosphorus. Phosphorus reacts with the UV radiation by fluorescing- giving off visible light. Technically, both of these elements, the argon gas and the phosphorus paint, are fluorescing, but since the human eye can’t perceive UV light, only the phosphorus fluorescence is noticed.
Fluorescent lighting took its first significant steps in the mid 20th century. In 1856, Heinrich Geissler was able to create a partial vacuum in a glass tube and created light by running current through the residual mercurial gas inside. The Geissler tube quickly became a novelty item of the wealthy as scientists learned they could create different colors of light by introducing different chemicals. This was the precursor to both the neon light and the fluorescent light. In 1859, the first fluorescent effect was observed in a Geissler tube. In the early 1900s, several experiments were done with fluorescent tubes and growing plants. Fluorescent lamps continued to see increasing popularity among biologists as their luminescent capabilities increased throughout the 21st century.
Fluorescent lights are more energy efficient than incandescent lights, and the heat output is very low. However, because they rely on physical reactions of chemicals to produce light, fluorescent lights are limited in the spectrum of light they can produce. Most fluorescent lights produce light mostly in the blue spectrum. There do exist fluorescent grow lights that can produce light in a broader spectrum, but they are rarer, and fluorescent grow lights that produce lights throughout the spectrum from UV to IR are so rare as to be experimental. This is because to create a broad spectrum fluorescent light you need several reactive agents in the lamp, and controlling these elements to create anything like a broad spectrum of light is very difficult. It’s also concerning that fluorescent bulbs are prone to breaking – sometimes explosively, and when they do, the chemicals within spill out with the shattered glass.
HID: HPS and MH Grow Lights
HID stands for High Intensity Discharge. Where fluorescent lights are the evolution of gas discharge lights, HID lights are the evolution of open-arc lights. They still rely on an arc of electricity passing between two electrodes, but science has improved on the containment and illumination.
What we call HIDs were developed in the 1960s after a series of innovations first contained the arc-light in a bulb-within-a-bulb design, then with the application of different metals, halides and pressures, the two most common lights seen in growing were produced: the High Pressure Sodium (abbr. HPS) light, and the Metal Halide (abbr. MH) light.
In the HPS light, a mercury-sodium amalgam is applied to the arc tube. When electricity is applied and the arc generates heat through the tube, the amalgam melts, giving off gasses of mercury and sodium. As the arc continues and the heat increases, the liquid metals evaporate entirely into gas, which creates a great amount of pressure within the arc tube. This results in very bright, wide-spectrum light.
In the MH light, much the same thing occurs, only a mercury and metal halide gas is used instead of a solid-state sodium amalgam. A metal halide is a compound of a metal and a halogen. In MH lights, this is most often sodium iodide. Originally, the arc tube for MH lights was made of quartz, but at the 1981 World Light Fair, the first MH light using a ceramic tube was introduced, showing a much greater life span and resistance to heat than the quartz tube. However, because of the costly need for a ballast to run HID lights, the first commercially available Ceramic Metal Halide(abbr. CMH) light was not available until 1994.
Although these lights are able to produce light of a broad spectrum, their output is such that they were not seen as a great contender for the sun for many decades until 2010, when the double-ended HPS light was invented.
Using two points of contact in a thinner bulb, the frame wire holding the arc tube becomes unnecessary in a double-ended HPS light. The bulb around the arc tube is also filled with nitrogen gas in a double-ended HPS, where in a single-ended HPS light, the bulb is a vacuum. The double-ended bulb allows for a longer arc tube, which means more reactive gas, and the nitrogen within the bulb creates additional light as the bulb heats up. The double-ended HPS quickly became the light of choice in the grow light industry.
Although their output is significant, HID lights are not very efficient bulbs. They use a lot of electricity that has to be regulated by the ballasts. There are many different kinds of bulbs that produce different intensities of light, using different wattages, and the grower must be aware of what reflector they are using with their particular light. Because HID lights rely on ignition to produce light, they generate a tremendous amount of heat, and can potentially melt a reflector that is not designed for the higher wattage being used. The spectrum of light produced by HID lights are not very reflective of sunlight either, and often growers are inclined to use MH lights for one stage of growth and HPS for another. The specialty bulbs are not cheap, and the heat they produce is enough to damage any container. Most growers find they have to replace these spendy bulbs every 6-9 months. Ultimately, they are a bulky, boiling type of light that is not recommended for home growers.
A History of Problems
Every light sold as a “grow light” is an attempt to replace the sun in an effective, controllable manner: a manner that gives the plants the light nutrients they need to grow without creating environmental hazards.
Whether it’s poor illumination, a shallow color spectrum, or an exorbitant amount of heat, these antiquated grow lights are all wanting in efficacy as healthy light sources for growing plants indoors, especially for smaller operations or home grows. Frankly, however far they have evolved, they are still, at their core, the same inefficient lights concocted by Victorian scientists over a century ago.
These issues are easily avoided however. Thanks to innovative thinkers applying technology to higher standards.
LED Grow Lights
LED lights create light by passing electricity through semiconductive crystalline material like silicone in a process called electroluminescence. LED lights are often thought of as a new technology, but did you know that the first LED was actually invented in 1961? Though there had been several discoveries of light moving through diodes and different metals, James Baird and Gary Pittman discovered an electrical pulse through a tunnel diode of a gallium arsenide substrate produced infrared light. The very next year, the first red LED in the visible light spectrum was produced by two separate teams in the UK and the US.
These early LEDs were costly and impractical for use in anything but expensive lab equipment and computers, where they were used as indicator lights for different mechanical processes. However, as the years progressed and technology improved, the quality of light improved in LEDs significantly, and the cost decreased at a rate so remarkably observable that a scientist named Roland Haitz created what is called Hait’s law, which states that every decade, the cost per lumen goes down by a factor of 10, and the the amount of light generated goes up by a factor of 20. This observation was first made in 2000, and it still holds true today.
In 2016, our CEO Dan Drazba saw the potential of the ever-advancing LED, and set out to develop an LED fixture that would produce a broad-spectrum, high-intensity light that provided plants with everything they need to grow as robustly as under sunlight. He knew the tech was available, he just had to develop the light. Thus was born the Electric Sky, and with its proven success, many other companies have moved into LED grow lights as well.
LED lights are comparably very efficient lights, using a small fraction of the electricity to produce more light than other grow lights. Also, because of advancing tech, we are now able to produce LEDs that emit light in near perfect imitation of sunlight’s color spectrum. Because the light output of an LED can be controlled by how it is built, the possibilities are endless.
LEDs produce less heat than HID lights, and are capable of replicating sunlight better than any other option. They are somewhat fragile, however, and generally require a low voltage direct current to operate. This is why most LED light systems will include a driver, to regulate the electrical current.
Popular belief dictates that plants only make use of the red and blue wavelengths of light, when in reality, plants make use of the entire spectrum in order to grow. This misconception began when research in the 1970s extracted chlorophyll from plants to experiment and test what colors they absorbed. The flaw in this experiment was assuming that how chlorophyll reacted translated to how the entire plant used light. This would be equivalent to testing reactions of your red blood cells and determining that the only thing you need to survive is oxygen.
We now know that plants use light in a wide range of colours, and they use each color in different degrees. Only LED lights can be built to produce light that cater to the specific needs of your plants. Check out our blog on how plants use light for more information.
PPFD; Another Outdated Idea
Photosynthetic Photon Flux Density, or PPFD, is a measurement of how many particles of light hit a particular spot every second. It has traditionally been used to record light mostly within the visible spectrum. However, research has suggested that this range should be expanded. Biologically Active Photon Flux Density, or BPFD, which includes colors through the ultraviolet and infrared spectrum is a more accurate scale to use when measuring how much light is hitting a certain spot that your plants can use. Infrared has generally proven to be most beneficial for crop yield and growth speed, but both IR and UV light offer benefits that boost plant health.
When developing our own LEDs, this need for plants to receive a wide range of light was carefully and meticulously attended. LEDs are versatile enough to allow this kind of fine-tuned designation. If you’re looking for more information on this subject, here’s our blog on BPFD and PAR values.
Cooler Operating Temperatures
As any indoor gardener will tell you, controlling the environment of a grow is a constant concern. Lights that produce an exorbitant amount of heat can completely destroy a garden, so countering the heat with complex and expensive cooling systems becomes necessary. LEDs produce far less heat than HID lights so you spend far less time and money on keeping your garden cool. Without having to compensate for the heat generated by other lights, your grow room environment will be stable as it reduces temperature and humidity variations that could damage your crop’s growth.
The Final Choice
When navigating the flood of information and ads that rock the web, the task of finding the right light for your grow setup can be daunting. But taking everything that we’ve learned here, it’s easy to see that the criteria for choosing the best light can be plainly laid out as follows:
- luminescence- Is the light bright enough (and can it stay bright enough) to keep my plants healthy?
- color spectrum- Can the light produce a full spectrum of color so my plant can use it to maximum growing potential?
- heat- Will the heat runoff from this light be too much to control?
Artificial lighting, as you can see, has evolved quite a lot over the past 200 years, and with technology continuing to advance at exponential rates, you can bet that evolution is set to get even more impressive quickly. Because fluorescent lights and HID lights rely on outclassed methods of luminescence, their inefficiency is only going to become more and more evident as time goes on. Fluorescent lights, while masters of the heat control game, can never be up to snuff in the luminescence and color spectrum departments. HID lights may have a good handle on the luminescence and color spectrum, but the heat the produce is deadly unless somehow mitigated. Technology, in the form of LEDs, has answered all three criteria in stellar fashion, and LED lights will only continue to improve upon those standards.
Now that you know how LED lights increase plant growth more efficiently, you are ready to start making some informed decisions. Between being educated and finding equipment with the greatest ease of use, you’ll be able to efficiently cultivate healthier and stronger plants. Make the right choice and try our LED grow lights for adjustable levels of light for each phase of the growth cycle.