Do you incorporate UVB into your lighting array?

Please allow me to preface this topic with a little disclaimer: this topic warrants more research into the effects of UVB light on cannabis plant response…but there are many growers out there who swear by the use of UVB light (including yours truly), especially during the final stages of flowering. There are some growers who are just fine without UVB. Research has shown that UVB light can be dangerous to humans by changing otherwise healthy cells into cancerous cells, but, in my experience, plants love it and respond by producing more resinous, sticky, and terpene-rich buds.

@growopowners, @mastergrowers, @GrowOpEmployees, @EquipManufacturers, @Lighting and really anybody else who wants to get in on this discussion: do you incorporate UVB into your lighting array? What are your thoughts on UVB?

Illuminate us with your reason!


Black Dog LED has always incorporated UV into our fixtures utilizing LEDs. However, we incorporate UVA into our fixtures, not UVB. There are a number of reasons that we use UVA, some of which include safety, efficiency of the current technology, and longevity of the current LEDs on the market.

We have done multiple controlled experiments showing that the UV does indeed increase active compound production. We have shown increases of over 10% in active compound production when compared to HPS or other LED lights that lack meaningful amounts of UV.

Anyone interested in this may find these FAQ’s on our site interesting:

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

How much UV light do PhytoMAX-2 LED grow lights provide?

Happy gardening,
Black Dog LED


I use the california lightworks for my winter grows which have the UVBs built in and provide plenty of heat! Not sure if they help or not but I do turn them on for the last 4 weeks or so of the grow.


The FAQ on your website is very useful. I refer to it a lot. Thank you!


Heard your interview Nick - very inspiring! I am very biased toward allowing UVB to shine through all new greenhouse glazing. If one goes to the Google Scholar search engine, one finds a ton of credible academic studies that verify the direct relationship between UVB and powdery mildew suppression. I have recommended Phillips double ended HPS grow lamps that have a fair share of the UVB spectrum. None of my clients have ever had a powdery mildew issue. Of course there are a myriad variables that contribute to the suppression/proliferation of powdery mildew. I have yet to deploy LEDS.

Happy growing


Thanks so much for taking the time, @raymond. I appreciate your kind words. I am also a huge proponent of using UVB – especially the UVB naturally emanating from the sun! You made an interesting point about the PM that I had forgotten: the UVB and UVC light have fungicidal properties. Interesting to note that I also have rarely seen outbreaks of PM in facilities that use UVC sterilization and UVB light as supplement to existing lighting arrays. I love a combo of LED and UVB lights: nice and cool.



I really though about UV exposure since college. Now after a second skin cancer removed or three?

I have an opinion.

  • If higher anamals are not exposed to any additional UV than a traditional farm worker fine.
  • But, you should not run any UV lighting when higher anamals are working or present. Period. :point_up_2:

You maybe seeing a difference in production and productivity. It is definitely a good thing for fungus control in an IPM SOP. This is where we need our university studying and documenting in medical cannabis. That’s good.

But, do not add to the life time risk to employees or owners.

From the voices in my head


I agree the risk of cancer caused by exposure to UVB is without dispute. I believe that through proper risk mitigation through PPES as part of SOP is absolutely necessary. This is where folks like @RayWearCC stand to provide the industry with a much needed service.


I don’t think you need as much uv as you think. Plants get saturated with UV quickly. My guess is 20 min in an hour will give you equal to 60/60. I would think 5 minute every fifteen, the question is total daily saturation. I bet only the 16 hours people not present gives lots of room to use uv with no extra protection.

Think about the opportunity cost of the light.

From the voices in my head


Great info, thanks all! What are thoughts on UVA and UVC in the grow?


Heya Ethan. Many of the workers in the licensed growops up here are gowned from top-to-bottom for biosecurity protocols. It wouldn’t be a stretch for said workers to wear the appropriate eye and face protection. Our local mandated work standards only allow for a very nominal amount of ozone to be present in the air. ‘Supplemental’ UVA and UVB lighting, enough to make a difference for the plants, would be a non-issue…methinks.

I really appreciate your insights. It is always a pleasure.




I love you! You make me think :slight_smile:

You may be right but, I want some facts before I walk into a UV environment higher than the noon day sun. I don’t want to walk into a tanning booth, and look like 45. :rofl:

But all fun aside, we have good documentary proof for bio control of fungus and some insects (thrip and some mites do not like UV light. Two Spotted mites glow under UV makes quite the photo. Old Viola oderatera trick from a 1920’s era Grower, with a black light.

If growers are reporting improvements we should discount them we should quantify them.

If I remember from plant physiology the saturation index for UV is low in most non funny plants. Some Cactus do a strange thing in there C3 cycle to maximize total radiation storage and use it at night like a c4 plant. lets call them C3.5 plants.

But cannabis is not one of them. Maybe we see an injury response with high UV and the resin is an expression of that functions.

from the voices in my head


Hello @ethan and @raymond

To both your points, yes, there are real issues with regards to light radiation with all grows…outdoor, greenhouse and indoor. With outdoor and greenhouses, it is more of a UV issue. With regards to indoor, depending on your light set-up, there are significant risks from UV, Visible and Infrared. We actually created our fabrics specifically for this environment.

To your point Ethan, the “cover-alls” some modern grows have their team wear are simply for sanitation and do next to nothing for light radiation. They are specifically designed to protect the plants from the workers, not the worker from the light radiation in the room. It is a very common misconception that just because your skin is covered, then it is protected. This is simply not true.

The good news is the industry is slowly starting to realize the health risks associated with cultivation and we at RayWear have created very effective solutions to ALL light radiation environments that growers face. With RayWear gear, you can work in any grow, regardless of which lights are on, and still be completely safe. Our gear is over 50+ UPF, significant reduction in IR and we block up to 99% of visible light. We are the only product on the market offering this level of protection. So being safe in a grow is now as easy as changing your shirt. And not to brag, but our gear is ridiculously comfortable as well.

But it is awesome that this is a topic now, 2 years ago this topic couldn’t get any traction, but I am glad growers are getting informed and making better workplace decisions for themselves and their future. Please feel free to message me directly if you have any questions about light radiation risks. Be safe and happy growing!

from the other voices in Ethan’s head,



I want to talk about it. PM me please.

From those pesky voices in my head

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It is not bragging. It is a fact, very nice martial, and unbelievably comfortable. It is not comparable to common scrubs, which mostly are not fun to wear and are not comfortable for long hours.


Thank you so much @fdousty
I am very happy you like the gear!!!


True story. I wear my RayWear for hiking and fishing all the time…and in my grow under the lab coat


When I look up UVB lights, the returns I get are mostly for reptiles, or are already incorporated with COBs or LEDs. Can you suggest a stand-alone UVB light that I can add as supplemental lighting? I already have a COB set up. Thank you.


Hortilux carries cost effective T5 UVB bulbs that can be easily added to any lighting array


UVB is becoming the most accepted for potency application. Use your PPE! UV LED chips are naturally self destructive. Mixing them into an array guarantees that they’ll be the first to fail and can cause the christmas light effect unless you have SCRs at each LED to buffer the failure. This drives up the cost of the total fixture and not worth it imo. Stand alone UV fixtures either T5 (repto or horti) or LED based, and specific timing/ the ability to toggle when grower isn’t in the garden is the way to go for now.