ePAR and UV Lighting: The Connection

For decades, growers have been using a specific system to determine how much photon exposure their plants are getting. But what if we tell you that this system is no longer as accurate as it once was? What happens if the whole idea requires a bit of updating?


That’s exactly what’s happening in the lighting cultivation world today. Recently, researchers discovered that the PAR system we’ve relied so heavily on for years might not actually illustrate the information we need. Thus, we introduce ePAR.


Don’t panic if you’ve never heard this term before. It’s just now making its way into the world of cultivation lighting, and we’re still learning more about it. Specifically, today, we’re taking a look at the connection between ePAR and UV lighting. What’s the connection, and how can it help our cultivations? We find out.

What is ePAR?

Before giving you a clear definition of ePAR, we have to first discuss what PAR is and how cultivators utilize it.


PAR stands for Photosynthetically Active Radiation, and it’s defined as a type of energy that helps to drive photosynthesis — hence why it’s so essential for plant cultivators. Back in the 70s, a doctor named Keith McCree believed that PAR levels must fall between 400 to 700 nanometers to be adequate for photosynthesis. Any more or any less than that is out of the realm of possibility for benefits, leaving cultivators to strive specifically for this range of numbers.


However, as time went on, cultivators started questioning this strict number range. How was it possible that these numbers worked out so evenly, ending in perfect 00s? Could 701 or 399nm really not be effective at all?


Doctor Bruce Bugbee wondered this, too. Through multiple studies and comparative research, Dr. Bugbee discovered that he was right in questioning the rigidity of these numbers: plants had the ability to hold an even more comprehensive range of radiation than McCree thought.


When tested, Bugbee found that photons within the outlying ranges (315-400 and 700-750) held the potential to help with photosynthesis. At first glance, these ranges didn’t produce strong results; however, when produced alongside other PAR photons, the effects were apparent. The doctor understood that numbers like these couldn’t just be ignored, and through published research and studies, he let other cultivators know his discovery.


Thus, we have the creation of “ePAR.” Once Bugbee realized these extended radiation ranges, quantum meter producers hopped on this idea quickly. Soon, Apogee Instruments coined the term ePAR (extended PAR), manufacturing PAR sensors with this new range of numbers.


Why Use ePAR?

If we’ve utilized PAR measurements for so long, why switch to ePAR? What are the benefits?


As we’ve established, relying on the traditional PAR ranges excludes potential radiation photons, subsequently producing inaccurate numbers in terms of radiation output. When we switch to ePAR, the numbers we get with our cultivations will be much more accurate, allowing you to have better, more successful plant growth at the end of your harvest.


Perfecting your cultivation will follow suit once we become a bit more familiar and comfortable with these new lighting ranges. Understanding these extended PAR ranges allows us more fulfilling insight into our plant’s potential. Who wouldn’t want to achieve this?


The Connection Between ePAR and UV Lighting

Now, let’s get into the good stuff: what’s the connection between ePAR and UV lighting?


Plain and simple, plants thrive off of proper amounts of UV lighting. UV can help protect plants during growth, helping them become more disease-resistant and healthy. Along with this, UV lighting is wonderful for strengthening plant growth overall, as it provides added nutrients and gives your crops a bit of a boost. If grown outdoors, your plants would have been exposed to the sun throughout the day. Sunshine contains UV rays that your plants would soak in and use to grow. Because of this, it’s essential to attempt to replicate this with your indoor cultivation.


Unfortunately, UV lighting isn’t visible to the human eye, making it more challenging to utilize during cultivation than LED lights. Thankfully, we now have measurements like ePAR to help us out.


ePAR instruments will let growers know the amount of radiation they have versus what they need to activate photosynthesis. Previously, while cultivators believed they were getting the right readings from PAR meters, the numbers weren’t accurately reflecting radiation levels. Now, we’re able to better understand how much energy our plants have and whether or not we need to adjust UV lighting levels.


Without these accurate measurements and mastering UV exposure, your plants shouldn’t have any problem starting the photosynthesis process. Using ePAR, finding perfect energy levels comes more effortlessly than ever before. All you