Understanding Full Spectrum LEDs
and PAR Readings
When it comes to measuring the amount of effective light an LED, High-Pressure Sodium (HPS), High-Intensity Discharge (HID), or fluorescent light fixture emits for a plant to use, there are two primary measurements that should be identified and analyzed together; PAR and the light spectrum measure.
First, PAR or Photosynthetic Active Radiation is essentially a measurement of light emission within the photosynthetic range of 400-700nm. This represents the area of light that plants actually use for photosynthesis, or to grow. PAR is measured by the number of micromoles of light per square meter per second.
Although PAR is a key measurement, it only tells one part of the story. There are many areas within the PAR scale which plants absorb only in small quantities, such as in the green range (560 nm). Thus, a reading of a light’s spectrum must be used in conjunction with the PAR reading to determine from what bandwidths those micromoles are being generated, and in what amounts.
A spectrum reading is obtained by using a piece of equipment called a spectrometer. These two readings, PAR and spectrometer reading, together, will give a complete picture of a light’s effectiveness; PAR showing strength and spectrum showing that this strength is in the proper wavelength proportion for what the plant can actually utilize, and not just wasted energy. This is referred to as "absorption value".
These two measurement tools produce a reading that shows not only what wavelength or color is being emitted, but also the absorption value of that particular wavelength. By looking at this graph, one can determine if the light is emitting the proper wavelengths used by the plant for photosynthesis and at the correct absorption peaks required for robust and quality plant growth. HID lights are a classic example as to why your consideration of both of these readings is so important. These traditional lights have decent PAR readings, but when their spectrum is revealed, it becomes evident that they emit most of their energy in the wrong areas, making them an inefficient lighting option. Kind LED Grow Lights on the other hand, compared to HID lighting, as well as to other LED lighting options, show extremely high PAR readings with an efficient and accurate distribution of strength across your plants’ desired spectrum.
PAR Reading Comparison at Various Footprint Intervals
KIND LED Light Spectrum at 24 Inches with Plant Absorption Percentage by Nanometer Overlay
LED’s Allow Us to Target Specific Spectrums, But What Are White LED’s?
Kind LED’s have been designed to have a full yet targeted spectrum for growth and/or flowering, and don’t waste any energy emitting large amounts of spectral ranges that plants don’t use high amounts of. We specifically target the areas with the highest absorption rates in order to deliver exactly what the plant needs for photosynthesis, and not a bunch of light the plant otherwise sees as useless.
Lately, there has been a wave of companies that are using all white LEDs in their design. These lights follow the more familiar color temperature range that we commonly find in HID and T-5 bulbs, 2700K-6500K. Although this makes a light that is closer to what we are all used to seeing as far as color, it negates one of the most important benefits of LED lights, not wasting energy on light that the plant can’t readily absorb and use!
Some companies which are selling white LEDs have been touting that these lights replicate the spectrum of the sun. That’s a marketing claim which does not get to the core fact that the big difference between the sun and your grow light is that the sun has an endless supply of nuclear energy, whereas the real need by Cannabis plants is only a fraction of this energy within certain spectral ranges. Your plants and pocketbook, on the other hand, need only a specific portion of this output and the rest is wasted energy.
This full spectrum marketing falsity is similar in nature to how HPS lights perform. HPS bulbs use various gases to produce spectrum ranges in 3 areas which are spectrum-limited. Sodium, Mercury, and Xenon are the main gases within these bulbs. Sodium by itself produces a mostly yellow spectrum range, which is why HPS are subject to wasted light in areas that Cannabis can not benefit from. It is then mixed with impurities to produce other colors of the PAR range such as Mercury, which is responsible for the limited Blue range in HPS bulbs.
The bottom line is that Kind LED lights provide the best useful array of light energy which optimizes our investment dollars and the on-going Total Cost of Ownership for Cannabis and Hemp crops over an unmatched length-of-life.