LED Grow Lights Beam Angles Explained
One of the things that really confused me when I was first researching LED grow lights was the beam angle.
The companies selling the LED grow lights were always saying things like, “120 degree beam angle for maximum coverage.” Or “90 degree beam angle for great intensity.” Or “60 degree beam angle for maximum penetration.”
As I read this advertising I sat there dumbfounded. This is what I was envisioning in my head:
Well, it turns out that my first assumptions were incorrect. The LED grow light experts are not talking about the angle from the light fixture when they talk about beam angles. They are talking about the angle of the light that is coming out of each individual light emitting diode. Remember that each LED grow light you purchase is made up of many individual LEDs. These individual LEDs look something like this:
Each diode’s beam angle can be controlled.
One of the great things about LEDs is that you can control the exact angle that light comes out. With traditional HID lights there is no control over these beam angles.
This means that traditional HID lights are always shooting out at 360 degrees in all directions (this is a waste of energy). Even if you have a reflector, you are still losing some light from an already inefficient light source.
As you can see in the diagram below, a 120-degree beam angle really spreads the light beams out. A 90-degree beam angle is more concentrated and a 60-degree beam angle is even more focused.
That is a great question, and unfortunately, the answer is, “it depends.” You see, an LED grow light with 120 degrees casts a wider net. This means that a 120 degree light has a larger coverage area because the light is spreading out everywhere.
You can fit more plants under a 120 degree light than you can with a 90 or 60 degree light. However, the 120 degrees light is not as concentrated and does not penetrate to the lower levels of the plant very well – a wider beam angle means lower intensity.
Most experts agree that this beam angle should only be used on plants that are very short, non-flowering plants like lettuce and herbs, however, even those plants can grow better with more intensity.
On the other hand, the 60 degrees light does not cover as much area as the 120 degrees light does, but it emits plant-growing light farther and at a higher intensity.
That is why you are seeing most of the newer LED grow lights with 60 and 90-degree beam angles, a combination of both, or secondary lenses. This has been a step in the right direction for those growing light-intensive plants like medical marijuana, tomatoes, peppers, etc.
In fact, some of the early grows with LED grow lights didn’t turn out as well because the wide beam angles didn’t allow for proper penetration which resulted in poor flowering. With more narrow beam angles, this early problem appears to be a thing of the past.
In summary, beam angles refer to the angle of each of the individual LED chips. It does not refer to the angle of the light fixture itself. You might be okay using a 120 degree LED grow light for shorter, less light-intensive plants, but for most growers, a more narrow beam angle is what you need.