Here is an important concept and a tool that you need to learn about and use to properly measure the light output of your grow light setup, to help you achieve maximum plant growth while minimizing electricity costs. I’m talking about measuring LED lumens using a light meter. This tool tells you how much actual light is being produced, versus electrical power consumption.
Are you already using a light meter to help grow your business? If not, read on. I give you some useful explanations, and also below I review and recommend top 5 light meters, one of which I suggest you invest in for your growing business.
Another very important concept to know about is PAR, which deals with plant light spectrum. Read on to learn more below.
What is a Lumen?
When dealing with LED lighting one needs to think in terms of lumens not watts, whether replacing the old incandescent bulbs in your house with new LED bulbs or whether you are installing LED grow lights for a large-scale industrial grow farm. As we all know, traditional incandescent bulbs measure their light output based on Watts, a 100 Watt bulb for example. But as we’re also painfully aware, those things get HOT since much of that energy in old-style bulbs is actually getting dissipated as heat rather than light. And while wattage does help explain how much energy is being consumed, it’s not a good way of measuring light output. I’ll explain why.
This fancy term lumen is basically just a standard unit of measure of the “amount” of light produced by a given light source, in other words the luminous intensity of the light source. Historically, this goes back to the original way of measuring light using the standard output of 1 candle power.
In addition, there’s another important term you might hear about, called “lux” which is related to lumen but lux gives you a better measure of how focused or spread out the light source is. Think of the difference between a regular bulb and a laser; a laser focuses all the light in one point and therefore has a very high lux value, compared to a regular bulb that produces more diffuse spread light. So this is about as detailed as I think we need to get right now, but of course you can always get more info at Wikipedia here.
Long story short, more lumens = more light.
Remember, more watt does not necessarily give you more light (just a higher electric bill, ouch!) A more appropriate way to think is in terms of lumens per watt, which is also called “luminous performance” or “luminous efficacy” and essentially tells you how efficient your light source is in terms of lumens per watt.
So now you can understand how two sources, say a regular bulb and an LED light, could both potentially produce the same amount of light but they will each consume a very different amount of energy (watts). I think it is common knowledge that LED lights are WAY more energy efficient at producing light (lumens) for a given amount of energy.
What is PAR? Overview
As I’m sure you know, the reason plants are green is because they actually reflect most green light, while they absorb most of the rest of the light spectrum. This means that plants don’t really need green light, because for some reason green light doesn’t have the proper energy content to promote photosynthesis in plants. Yet the light at the other ends of the spectrum, namely orange, red, Infrared, as well as blue, violet, and even Ultra-violet, are just the kind of light that plants need.
Understanding Plant Light Spectrum
As shown in the spectrum diagram above, the white curves represent the typical plant response to light, in terms of the photosynthesis chemical reaction that occurs inside the plant as it absorbs light energy to create food for itself. You can see a big dip in the white curve around the green & blue-green regions, this is the light that is relatively useless for them.
However, in the same diagram above you see the white curves peak in the violet regions and deep orange and red. This is the kind of light that plants love and need to grow and bloom. The best grow lights are the ones that are tuned and designed to deliver these particular plant light spectrum bands that the plants need. There is absolutely no reason for your artificial lights to be producing green light, that is just a total waste of energy.
The beauty of LED lights is that manufacturers are able to finely tune the spectrum to deliver the appropriate light, therefore minimizing wasted energy. No other light in the market, except LEDs, gives you this benefit.
So, based on the above discussion you can see that LED grow lights give you two main benefits:
– More Lumens of light output per Watt
– More usable plant light spectrum
What is PAR Measurement?
In addition to understanding what is a Lumen, you should also understand what is PAR. PAR is an abbreviation for the scientific term Photosynthetically Active Radiation. This is just a fancy term for describing the type of light spectrum that plants use. Generally, this covers the wave band (spectral range) of solar radiation from 400 to 700 nanometers which is also in the range of visible light.
But unlike the human eye, plants prefer light at both ends of that spectrum. This is the light that photosynthetic organisms are able to use in the process of photosynthesis. So ultimately, you want to look for a plant grow light that mimics this range of light.
Most LED grow lights provide you with a PAR measurement, which is a measure of the photosynthetic photon flux (area) density, or PPFD. You may see reference to PPFD in the light