Use of UVA and UVB light!

[DeepCreekFarms]

Ok I want to get thoughts on the use of uva and uvb lights. It’s my understanding that finishing off under uvb is quite beneficial but I’ve also read that using light doses throughout flower can also be beneficial. I’m making the switch from gavita double ended to the 1700e leds and gavita makes a uva led that can just fit in the 1700 fixture. My scheme is to put one or two of the uva strips into each fixture and then have separate uvb lights in between each fixture so I can just kick on uvb lights for 2 to 3 hours each day towards then end knowing that uvb is actually not good if used too much. This being the case will it be ok to be running the uva lights in sequence of the regular light cycle because they’ll be installed into the fixtures? Is uva nanometer (nm) output ok to use throughout all of flower knowing that uvb (nm) may not be beneficial if used too much? I hope I worded this ok… hit me with your thoughts and knowledge, thanks!

 

[Moe.Red]

OK, where to start.

Deep breath.................

There is a significant amount of contention about UV. Even the name UVA or UVB is misleading. They are not a thing, they are a spectrum.

This is an incredibly long thread, but worth it if you are serious about learning the tricks

Should I add UVB Light?

Hello, I have been growing on a very small scale for about 4 years. I am always trying to learn more about growing and I know that I have so much more to learn. I also know that it's probably a life long process! I started with auto-flowers in a 2 x 2 tent with a horrible LED light. I also...

www.thcfarmer.com

I did a whole bunch of testing with UVA LED bars and UVB florescent tubes. Specs and details in that thread.

TLDR: UVA seems to benefit the plant in terms of color; potency and growth benefits need to be studied more. UVB is quite a range of spectrum and there are currently no LEDs that produce it well or for long - they burn out quick. UVB can damage plants or can improve cannabinoid profile depending on use. The addition of trichomes via UVB is a common statement made by people that use it, I found no evidence to support this.

 

[DeepCreekFarms]

Ok I appreciate that a bunch! Lol and I certainly know that these are spectrums and not things;) my wording may be shit. I will definitely check out that long thread thank you for that. Do you happen to have a quick answer for if uva strips would be fine to install in my fixtures and run all throughout flower? Is it safe? Already knowing that I can not do that with uvb spectrum.

 

[Moe.Red]

UVA is not nearly as potentially damaging as UVB. I have run my UVA for 10 hours during 12/12 and it steered the plants purple but did not seem to hurt anything.

 

[freezeland2]

I’m running UVA this grow in flower. I started it at 2 hrs per day and will increase by another 2 hrs each week. By week 6 UVA will be at 12 hrs. I will run that to the finish. Hopefully it’s beneficial. If not this UVA bar will be in the classified section. We shall see. It’s a HLG UVA bar if anyone is curious. It mounts right up to my HLG Scorpion.

 

[Kevuk]

I was going to add UVB but seen a video on YouTube saying it was pointless.

 

[DeepCreekFarms]

I’m running UVA this grow in flower. I started it at 2 hrs per day and will increase by another 2 hrs each week. By week 6 UVA will be at 12 hrs. I will run that to the finish. Hopefully it’s beneficial. If not this UVA bar will be in the classified section. We shall see. It’s a HLG UVA bar if anyone is curious. It mounts right up to my HLG Scorpion.

Ha right… my only concern would be with the gavita uva strip I can add it to my 1700 fixture, concern being it’ll be running 12 on right away in fixture. I’m thinking it’ll be fine because it’s so much less intense than uvb spectrum.

 

[DeepCreekFarms]

UVA is not nearly as potentially damaging as UVB. I have run my UVA for 10 hours during 12/12 and it steered the plants purple but did not seem to hurt anything.

So installing it into the gavita 1700 and just running it 12 on from the get go should be fine I’m thinking?

 

[freezeland2]

Ha right… my only concern would be with the gavita uva strip I can add it to my 1700 fixture, concern being it’ll be running 12 on right away in fixture. I’m thinking it’ll be fine because it’s so much less intense than uvb spectrum.

Probably but I didn’t want to chance it so it’s on its own timer.

 

[DeepCreekFarms]

Probably but I didn’t want to chance it so it’s on its own timer.

Makes perfect sense to me.

 

[mysticepipedon]

UVB seems to improve potency for me, but I've never tested it.

I agree with @Moe.Red on the trichome density — it has zero effect on that, in spite of a large number of growers who swear that is the case.

There is some real legit doubt that UVA or UVB do anything for potency. As I've said, it seems to me that it improves potency, because in one grow full of clones, I stopped using UVB and the plants seemed to be less potent than in previous grows.

 

[PipeCarver]

UVB seems to improve potency for me, but I've never tested it.

I agree with @Moe.Red on the trichome density — it has zero effect on that, in spite of a large number of growers who swear that is the case.

There is some real legit doubt that UVA or UVB do anything for potency. As I've said, it seems to me that it improves potency, because in one grow full of clones, I stopped using UVB and the plants seemed to be less potent than in previous grows.

I was considering adding one to my grow about a month ago and someone here posted a link to a Dr, Bruce Bugbee video, after listening to him I'm no longer interested in getting one and wasting money. It seems hes been all over it and there's no proof it adds potency.

 

[DeepCreekFarms]

I was considering adding one to my grow about a month ago and someone here posted a link to a Dr, Bruce Bugbee video, after listening to him I'm no longer interested in getting one and wasting money. It seems hes been all over it and there's no proof it adds potency.

Funny it’s the opposite for me. Actually love listening to Dr. Bugbee very insightful, but what I took from his videos has reinstated that I do wanna add some UV. Just for what I’m going for. Maximize quality, obviously everything else needs to be there, correct VPD, Co2 boost etc… but yeah from all the research I’ve done UV can and will benefit when used properly. Not just snake oil. Appreciate the input and response. I’ll get it figured out one way or another.

 

[mysticepipedon]

I was considering adding one to my grow about a month ago and someone here posted a link to a Dr, Bruce Bugbee video, after listening to him I'm no longer interested in getting one and wasting money. It seems hes been all over it and there's no proof it adds potency.

I posted that.

And he's right about how the original experiment was done — it was done on vegging plants and the THC content was of the leaves. He did not bring the plants to flower.

I will be trying far red light. He said it definitely increases yield. I had already gotten one with the idea of speeding up flowering, but I got it too late for my last grow.

 

[DeepCreekFarms]

I posted that.

And he's right about how the original experiment was done — it was done on vegging plants and the THC content was of the leaves. He did not bring the plants to flower.

I will be trying far red light. He said it definitely increases yield. I had already gotten one with the idea of speeding up flowering, but I got it too late for my last grow.

Perfect… I’ll be posting my results as well. So we can bounce off each other and see our findings. Ha a few months out from that.

 

[DeepCreekFarms]

Perfect… I’ll be posting my results as well. So we can bounce off each other and see our findings. Ha a few months out from that.

Also apologize if I’m not responding properly to the right person, lol new to this stuff. Forums and what not. Only joined to pass on knowledge as well as soak up anything I can.

 

[Interaxie420]

As far is know LED fixtures are not capable of emitting UVA/UVB with enough power to actually influence the plant.....

 

[Moe.Red]

I'll have some better answers in about 3 months. Right now I am doing a proper test with documentation.

In this vid (Day 1 of test) from a few days ago I had just transplanted clones into the net pots and got the environment perfect.

On the left is 60W Far Red. On the right, 60W UVA. All other setpoints identical. I will be measuring and reporting many things as they flower out.



I also have another tent where I am testing UVB vs control. Lots to learn here I think.

I will be describing the process, hypothesis, and results including cannabinoid testing in another thread once this is a bit further along.

 

[N1ghtL1ght]

As far is know LED fixtures are not capable of emitting UVA/UVB with enough power to actually influence the plant.....

Not true. I've seen a growreport where a single 310nm diode bleached a full canopy (small tent) all top leaves got stripes
Problem with UVB via LED is it's not diffuse enough

 

[N1ghtL1ght]

I also have another tent where I am testing UVB vs control

try a chemotype I (pure sativa) plant, as not all cannabis genotypes respond positively actually to UVB (see Lydon on that)
anyway, very nice to see some side-by-sides on 730nm - that'll be very interesting to watch. Very well, nice you're dedicated. Just don't go overboard (or your plants will look like mine hehe)
How would you estimate the R:FR (660:730nm) ratio?