LED technology has advanced significantly in the last 10 years. Let’s compare LEDs to the various other light sources available for hydroponic systems.
Let’s examine each type of light, its advantages and disadvantages.
Incandescent Bulbs
Incandescent lights were the first electric lights available. They were plentiful, cheap and available in a host of outputs. They are easily disposed of when their useful life is over. Unfortunately, incandescent lights were not very energy efficient to operate. Incandescents generated a great deal of heat. They also required frequent replacement. At one time, they were the only real choice for the home hydroponic hobbyist.
Incandescent Lights and Hydroponic Growers
Incandescent lights have pretty much fallen out of favour with all types of growers. These lights have a very limited output spectrum, so they really do not provide the energy plants require to flourish.
Since we have been concerned with wasting resources, incandescent bulbs have pretty much disappeared from the market. The heat and operating expense made them unsuitable for most growing locations. Today, except for certain types of these bulbs, the availability of incandescent lights is very limited.
Fluorescent Lights for Hydroponics
With the advent of “grow lights,” fluorescent lights became viable for hydroponics. Fluorescent lights now provide a better spectrum of light for growing, generate less heat, and are much more energy efficient than incandescent lights. The initial cost for fluorescent lights was once a hindrance to widespread adoption. As the initial price for fluorescent lighting dropped, they became much more attractive to growers. Since they could easily be sized for large or small installations, fluorescents proved very practical for hydroponics.
CFL Lights Replace Incandescents
Compact fluorescent lights (CFLs) pretty much spelled the death of incandescents. Since CFLs can use the existing infrastructure for incandescent lights, the only cost is the price of CFLs themselves. With the advent of inexpensive, larger wattage wide spectrum CFLs, incandescents disappeared fairly quickly from the growing scene.
Fluorescent Equipment Cost
Many hobbyists, use fluorescent tubes or CFL bulbs for their grows. The low cost of equipment (you can light a 4 X 8 section of plants for under $100) is a huge factor. The ease of installation and the lifespan of the lights and fixtures is a bonus to the hydroponic grower. Finally, the low cost of operation make fluorescents a good choice for both commercial and hobby growers.
Disposal of Fluorescent Lights Problematic
If a fluorescent lamp is broken, a very small amount of mercury can contaminate the surrounding environment. Due to the mercury content, discarded fluorescent lamps must be treated as hazardous waste. A definite drawback to their use.
HIDs and HPS Bulbs for Hydroponics
HID and HPS bulbs have been the gold standard for professional growers for years. They can be powerful lights that sit fixed above your crop and need only to be changed once each grow cycle from HID to HPS.
You can save changing the whole package each time, if you buy a convertible package. You just need to swap the bulbs.
When do HID and HPS bulbs require ventilation?
HID and HPS bulbs require ventilation, even in a large areas. If you are using them in an enclosed grow room, like a spare room in your home, you will undoubtedly need to ventilate, and perhaps cool, the room as well as the lights. Should you not be careful to keep these lights well ventilated, they can generate enough heat to damage or destroy your plants and start a fire.
Although not as energy efficient as fluorescents or LEDs, HID and HPS bulbs produce excellent light for plants and are the main choice for growers of medicinal crops.
Advantages of LED Lights
LED technology has advanced significantly in the last 10 years.
LEDs are more efficient than ever, give off less heat, and the costs are way down. LEDs can now produce the complete light spectrum needed for your plants. A big advantage of LEDs over HID lighting is the heat factor. For most LED installations you will not need extra fans for the growing area.
Lower Energy Cost for LEDs
Because of the low heat factor, LEDs can be placed a great deal closer to the plants than can HIDs. This reduces dramatically (rule of inverse squares see below the article) the wattage required to deliver the necessary energy to the plants.
Operating cost for LEDs is negligible compared to HIDs because of the much lower wattage required per square foot of plantings. The initial cost for LEDs is lower than HIDs, and the lifespan is much greater. LED grow lights typically last for 50,000 hours or more, whereas HID bulbs generally last only 10,000 to 18,000 hours. This gives LEDs an even lower total cost per grow hour.
LEDs are Popular with Hobbyists
LEDs are very popular with hobbyist growers, especially those limited to only a few plants. Since LEDs are compact, quiet, light weight, and low power they do not usually require ventilation. Whereas HIDs are heavier, require external ballasts and require ventilation which can be quite noisy.
LED Configurations for Hydroponics
Depending on the specific configuration, LEDs come in three basic packages – arrays, bulbs, and tubes or strips.
Most of us are familiar with the incandescent replacement bulbs for the home. Growers use socketed multi-led, spotlight type bulbs of under 100 watts for single plants – I use them to grow dwarf tomato plants. The rectangular shaped fixtures hold many LEDs and produce into the hundreds of watts which can be used for large grow rooms. Larger LED fixtures usually include a small internal cooling fan for higher efficiency.
The Full Spectrum LEDs
Growers who use HIDs early in the grow cycle of flowering plants, must then switch to an HPS bulb as the plants mature. LED grow lights on the other hand provide a huge spectrum of energy. Because of this, when you use LEDs, you don’t need to be bothered switching out lights as your crops mature. With LEDs, you can actually install a system that’s tailored specifically to the type of crop that you are growing.
Smaller Space Requirements for LEDs
LEDs require much less space than HIDs, and comparable space to fluorescents. This allows you to use them in more confined grow areas. Smaller size and cooler temperature means that you can put your lights much closer to your plants without risk of burning them. Depending upon the crop and the wattage of your LEDs, you should ensure that there is between 4” and 18” between the light and the plants.
Disadvantages of LED Grow Lights
Nothing is perfect, and neither are LEDs. Keep in mind that LED technology is advancing in leaps and bounds. A disadvantage today could be overcome tomorrow. LEDs are sensitive to the heat generated by other equipment. Over time, LEDs will change colour and become less effective.
As with any new technology, LED manufacturers are not agreed upon common standards and measures, so you run the risk of not getting what you thought was advertised. Big growers and suppliers regularly review LEDs. You can find many video reviews of LEDs on youtube.
LEDs are Less Powerful
HID lights were more powerful than LEDs, but this is changing. Power is important as the more power a light delivers, the more intense the light. And the more intense the light, the greater chance of complete nourishment for the entire garden.
LEDs Require Constant Height Adjustment
Because LEDs have lower power, and are kept closer to the plants, they, like fluorescents, must be raised regularly to keep from burning the plants. The grower must take care that the plants do not touch the lights, as this will kill the affected part. Most small growers have no problem with this ritual. I have my LEDs suspended by their cords and just shorten them as required.
LEDs Can Emit Harmful Rays
LEDs provide your crops with a great deal of light from the blue end of the spectrum. This is great, particularly when your plants are in the vegetative stage. Unfortunately for the grower, long term exposure to blue light, can damage your retinal cells (similar to ultraviolet damage).
LEDs can Cause Light Burn
Because of the proximity to the plants, LED users risk light burn on their plants, as opposed to heat burn. Light burn can severely damage your crop. Light burn will turn leaves yellow and then white. Without colour, the plant leaves cannot carry on photosynthesis and eventually the plant will fail.
Conclusion
LED technology has advanced significantly in the last 10 years. This has meant that there are several choices for lighting your hydroponic system, including sunlight, the best and cheapest source. For many of the reasons above, I prefer LEDs. The ease of use, the low cost of installation and operation, and the results I get from my plants are all reasons for my choice. Reviewers and industry experts agree that LEDs will become the dominant lighting type for growers within the next five years or so. The ability to use LEDs for anything from a single plant in a DWC system, to a 4′ X 8′ lettuce raft, for me is their greatest asset.
The Inverse Square Law
The inverse-square law works as follows: If you double the distance between subject and light source, it illuminates a surface area four times greater than the one before. This means that you will require four times the lumens from your light source. Practically this means that every time you double the distance from the plant, you must use a light source that is at least four times as strong.