Why do we include ultraviolet (UV) in our LED grow light spectrum?

With a wavelength of less than 400 nm, ultraviolet (UV) light has a higher energy content per photon than light in the 400–700 nm Photosynthetic Active Radiation (PAR) portion of the spectrum.

There are several justifications for not including UV radiation in an LED grow lamp. The cost of UV LEDs is ten times higher than that of LEDs in the PAR band. UV light is not taken into account when measuring PAR or PPFD. We obtain less photons per watt from our UV LEDs than from any other colour LED we use, as a result of the fact that UV photons require more power to produce than PAR photons.


Put another way, our lights could be made more affordable and our PAR measurement figures would appear even more impressive on paper if we swapped out our UV LEDs with other LEDs in the PAR spectrum. Therefore, why do we even bother adding UV to our LED grow lights?

Black Dog LED prioritises producing lights that deliver optimal growth outcomes above those that only look nice on paper. We include ultraviolet light in our spectrum because it promotes canopy penetration and produces higher-quality plants.

Plants undergo a variety of photomorphogenic reactions when exposed to UV radiation. UV-exposed plants produce more of these naturally occurring sunscreen ingredients: flavonoids, terpenes, antioxidants, THC, CBD, and vitamins. When exposed to UV radiation, plants develop additional trichomes containing these natural sunscreen chemicals as a further defence mechanism provided by trichomes. We develop higher-quality plants with richer attributes of the thing you're cultivating the plants for by incorporating UV in our spectrum.

Additionally contributing to canopy penetration and enabling more productive plants are UV grow lights for plants. UV light aids in the delivery of additional PAR-spectrum photons down into the plant canopy even if it does not directly contribute to PAR. When it comes to absorbing and transforming PAR light into energy that they can utilise, plants are remarkably inefficient. Only 3–4% of the photons that strike each leaf are used by most plants. While many photons "bounce" off leaf molecules and are not properly collected and used for photosynthesis, other photons travel through leaves entirely. Each time these "bouncing" photons bounce, they usually lose a tiny amount of energy, which causes their colour to shift more towards the longer wavelength and towards the red end of the spectrum. A 660 nm red photon, for instance, would lose some energy and maybe transform into a 750 nm infrared photon when it passes through a leaf. when a result, it would no longer be directly useful for photosynthesis, albeit it would still be beneficial because of the Emerson Effect. A photon that originates at the top of the canopy as a 440 nm blue photon may, on its first bounce, degrade to a 520 nm green photon, then to a 600 nm orange, and finally to a 660 nm red photon. This process increases the photon's chances of being successfully absorbed and used for photosynthesis as it passes through several leaves in the plant canopy. UV photons penetrate through more leaves in the canopy before deteriorating to an energy level the plant can no longer use since they begin with even more energy (and a shorter wavelength).

Even in dense plant canopies, ultraviolet light improves plant health and aids in increasing PAR delivery to lower leaves. We include a significant quantity of UV radiation in our spectrum for this reason. Although it reduces our photon flux efficiency values, it really promotes improved plant growth. Certain rivals assert that they create UV light, but they do not provide an amount because it is negligible.

Although growing under UV light requires a bit more money, we think you'll agree that the improved growth outcomes make it worthwhile!