Lighting TOPled The Manual.

[1guy1plant]

I emailed Mars-hydro a few weeks ago and asked about adding supplemental uvb lighting and they recommended it. I thought it was good customer service but it sent me into hours of research ( again) . There are a lot of differing opinions. I added 1 26 watt reptile bulb hanging in between my led's. My concern is that I have plants at different stages of growth and I have read that UVB is not good for them during veg stage only the last few weeks of flower. Then again others say it does not matter how long you run them. It is unreal how much info is out there. I am probably going to add another uvb bulb soon just based on manufacturers recommendation.

I think it would be easier to just move next door to muddy, or tang, or pop, or chester, or a multitude of other people on this site and just start hanging out at their house every evening.

 

[Feenix]

I emailed Mars-hydro a few weeks ago and asked about adding supplemental uvb lighting and they recommended it. I thought it was good customer service but it sent me into hours of research ( again) . There are a lot of differing opinions. I added 1 26 watt reptile bulb hanging in between my led's. My concern is that I have plants at different stages of growth and I have read that UVB is not good for them during veg stage only the last few weeks of flower. Then again others say it does not matter how long you run them. It is unreal how much info is out there. I am probably going to add another uvb bulb soon just based on manufacturers recommendation.

I think it would be easier to just move next door to muddy, or tang, or pop, or chester, or a multitude of other people on this site and just start hanging out at their house every evening.

Hey guy, Forget this if you already saw it . If not it answers a lot on UVB and explains the chemistry.

https://www.youtube.com/watch?v=lfiI78uN3Ks

 

[1guy1plant]

I have seen it. It is very informative.

 

[Torched]

Plenty of folks run UVB over the entire life cycle, just don't over do it if you are doing it full time.

 

[Feenix]

Plenty of folks run UVB over the entire life cycle, just don't over do it if you are doing it full time.

I guess the question is how much is over doing it?
With no benchmark, its hard to tell what is effective and what is wishful thinking. I run 15w at 8 hours and have no complaints on the quality of the end result.

 

[TaNg]

Ed Rosental suggests you use 10% of the total lights power so if 400w you want 40w of UVB.

 

[Bilbo]

This article is the only scientific report detailing the effects of UVB I can find, in fact it's the only scientific report of any kind I can find to do with UVB effects on cannabis plants of any type let alone just Sativas.

Lydon, J., Teramura, A. H. and Coffman, C. B. (1987), UV-B RADIATION EECTS ON PHOTOSYNTHESIS, GROWTH and CANNABINOID PRODUCTION OF TWO Cannabis sativa CHEMOTYPES. Photochemistry and Photobiology, 46: 201–206. doi: 10.1111/j.1751-1097.1987.tb04757.x

It is cited in other interesting sounding studies such as The Effect of Electrical Lighting Power and Irradiance on Indoor-Grown Cannabis Potency and Yield.

I'm a bit cynical so I'm not going to pay to read two studies that have been available for 6 and 3 years respectively but have not appeared as groundbreaking news anywhere I can find inside or outside the world of cannabis growing.

As always when you're online looking for something to do with cannabis growing, there are endless forum threads citing the abstract of the 1st study as proof of the theory. I have the feeling they have mistaken the meaning of the word "equivocal" for the meaning of the word "unequivocal"!

Here is the abstract;

Abstract

The effects of UV-B radiation on photosynthesis, growth and cannabinoid production of two greenhouse-grown C. sativa chemotypes (drug and fiber) were assessed. Terminal meristems of vegetative and reproductive tissues were irradiated for 40 days at a daily dose of 0, 6.7 or 13.4 kJ m[SUP]-2[/SUP] biologically effective UV-B radiation. Infrared gas analysis was used to measure the physiological response of mature leaves, whereas gas-liquid chromatography was used to determine the concentration of cannabinoids in leaf and floral tissue.

There were no significant physiological or morphological differences among UV-B treatments in either drug- or fiber-type plants. The concentration of Δ[SUP]9[/SUP]-tetrahydrocannabinol (Δ[SUP]9[/SUP]-THC), but not of other cannabinoids, in both leaf and floral tissues increased with UV-B dose in drug-type plants. None of the cannabinoids in fiber-type plants were affected by UV-B radiation.

The increased levels of Δ[SUP]9[/SUP]-THC in leaves after irradiation may account for the physiological and morphological tolerance to UV-B radiation in the drug-type plants. However, fiber plants showed no comparable change in the level of cannabidiol (a cannabinoid with UV-B absorptive characteristics similar to Δ[SUP]9[/SUP] THC). Thus the contribution of cannabinoids as selective UV-B filters in C. sativa is equivocal.

I notice nobody appears to have paid to read the full results of the study. $6 for 48 hours access here btw.

The basic gist I got from the above was that the drug type Sativas might produce more THC as protection against UVB but it's ambiguous at best.

Before I could even dream of adding UVB my scientific side would love to know the answers to a few questions raised by the abstract.

The effects of UV-B radiation on photosynthesis, growth and cannabinoid production of two greenhouse-grown C. sativa chemotypes (drug and fiber) were assessed.

How many plants each of drug and fiber type were grown?

What were the growing conditions, growing medium and vitally what type/spec of lighting was used as the main grow lighting?

Terminal meristems of vegetative and reproductive tissues were irradiated for 40 days at a daily dose of 0, 6.7 or 13.4 kJ m[SUP]-2[/SUP] biologically effective UV-B radiation.

How were they irradiated so accurately at that specific dose?
The first above ground terminal meristem can be the only one or one of many depending where you look, the definition seems quite loose as some botanist/biologists use it to describe the top of sideshoots as well but some don't so were all colas zapped or just the main stem?

What type of UVB lighting was used?

The concentration of Δ[SUP]9[/SUP]-tetrahydrocannabinol (Δ[SUP]9[/SUP]-THC), but not of other cannabinoids, in both leaf and floral tissues increased with UV-B dose in drug-type plants.

What was the increase? For me a minimum of 2% in all the floral tissues would be needed to make it worth a dedicated UVB lamp but if that was the case we'd have heard about it by now.

I'd rather add a cfl as I'd still end up with more THC than the UVB treated plant if I managed to add 5% extra yield to the floral tissues at the expense of not getting the THC rich leaves of the UVB one.

Thus the contribution of cannabinoids as selective UV-B filters in C. sativa is equivocal.

Ok so the scientist's results are equivocal as I said earlier and for me that's enough to see the UVB dedicated light as an unnecessary and inefficient use of energy/space that could be better used adding more proven bandwidths such as red, blue or white depending on what stage you want to boost growth.

I know that last sentence came across like something a robot would say, I'd really love to see a barrage of links to published and accredited scientific testing proving me wrong, especially as Indica's might benefit more from UVB if it really does encourage THC rich trichome production as a sort of biological sunscreen, it being a plant that prefers more temperate climes than Sativas.

Until science does it's magic and proves it works I'll be filing UVB in the "At Best Not Disproved" folder in my brain along with magnetized water.

 

[pop22]

This article is the only scientific report detailing the effects of UVB I can find, in fact it's the only scientific report of any kind I can find to do with UVB effects on cannabis plants of any type let alone just Sativas.

Lydon, J., Teramura, A. H. and Coffman, C. B. (1987), UV-B RADIATION EECTS ON PHOTOSYNTHESIS, GROWTH and CANNABINOID PRODUCTION OF TWO Cannabis sativa CHEMOTYPES. Photochemistry and Photobiology, 46: 201–206. doi: 10.1111/j.1751-1097.1987.tb04757.x

It is cited in other interesting sounding studies such as The Effect of Electrical Lighting Power and Irradiance on Indoor-Grown Cannabis Potency and Yield.

I'm a bit cynical so I'm not going to pay to read two studies that have been available for 6 and 3 years respectively but have not appeared as groundbreaking news anywhere I can find inside or outside the world of cannabis growing.

As always when you're online looking for something to do with cannabis growing, there are endless forum threads citing the abstract of the 1st study as proof of the theory. I have the feeling they have mistaken the meaning of the word "equivocal" for the meaning of the word "unequivocal"!

Here is the abstract;



I notice nobody appears to have paid to read the full results of the study. $6 for 48 hours access here btw.

The basic gist I got from the above was that the drug type Sativas might produce more THC as protection against UVB but it's ambiguous at best.

Before I could even dream of adding UVB my scientific side would love to know the answers to a few questions raised by the abstract.



How many plants each of drug and fiber type were grown?

What were the growing conditions, growing medium and vitally what type/spec of lighting was used as the main grow lighting?



How were they irradiated so accurately at that specific dose?
The first above ground terminal meristem can be the only one or one of many depending where you look, the definition seems quite loose as some botanist/biologists use it to describe the top of sideshoots as well but some don't so were all colas zapped or just the main stem?

What type of UVB lighting was used?



What was the increase? For me a minimum of 2% in all the floral tissues would be needed to make it worth a dedicated UVB lamp but if that was the case we'd have heard about it by now.

I'd rather add a cfl as I'd still end up with more THC than the UVB treated plant if I managed to add 5% extra yield to the floral tissues at the expense of not getting the THC rich leaves of the UVB one.



Ok so the scientist's results are equivocal as I said earlier and for me that's enough to see the UVB dedicated light as an unnecessary and inefficient use of energy/space that could be better used adding more proven bandwidths such as red, blue or white depending on what stage you want to boost growth.

I know that last sentence came across like something a robot would say, I'd really love to see a barrage of links to published and accredited scientific testing proving me wrong, especially as Indica's might benefit more from UVB if it really does encourage THC rich trichome production as a sort of biological sunscreen, it being a plant that prefers more temperate climes than Sativas.

Until science does it's magic and proves it works I'll be filing UVB in the "At Best Not Disproved" folder in my brain along with magnetized water.

Nice to see a good rebuttal! I looked at the same material you've posted and it just confirmed its another, I'll call it a garden placebo...the spread of myths like this become entrenched and people refuse to give up there believes, even in the face of science. I stated earlier, UV supplementing is not only a waste of money, the risks of exposure especially to your eyes, even for a few seconds, is ever present and will have serious consequences. I've read of people blinded while working with UV water treatment equipnent, not to say these lights! Spend your money on bigger or better lights, because, bigger better buds will have more trichs!

 

[Anthropolis]

Agrree, excellent rebuttal! My stance is:
1. I tried it and swear it helps (as has many who did), but that could easily be chocked up to increased experience, luck, alignment of the planet Jupiter, ect lol.
2. We all agree that the strongest plants ORIGINATED in the Hindu Kush range right? Ok, this region has a few key points: close to the equator (relatively speaking), and altitude. Sunlight increases closer to the equator and with increased altitude, but UVB increases exponentially with altitude. I believe with all my heart and brain, that the "best" (highly subjective) plants can grown indoors when the environment most closely mimics their "perfect" outdoor environment. This must theoretically include UVB. You want strong stems so you add wind (fans) right?
3. $50 for two UVB lights didn't bankrupt me lol, and it was worth a shot trying to more closely mimic the outside.
4. Agreed, there is significant lack of "scientific" evidence that it helps, despite plenty of anecdotes to that effect.
Just my stupid thoughts and opinions

 

[Bilbo]

Agrree, excellent rebuttal! My stance is:
1. I tried it and swear it helps (as has many who did), but that could easily be chocked up to increased experience, luck, alignment of the planet Jupiter, ect lol.
2. We all agree that the strongest plants ORIGINATED in the Hindu Kush range right? Ok, this region has a few key points: close to the equator (relatively speaking), and altitude. Sunlight increases closer to the equator and with increased altitude, but UVB increases exponentially with altitude. I believe with all my heart and brain, that the "best" (highly subjective) plants can grown indoors when the environment most closely mimics their "perfect" outdoor environment. This must theoretically include UVB. You want strong stems so you add wind (fans) right?
3. $50 for two UVB lights didn't bankrupt me lol, and it was worth a shot trying to more closely mimic the outside.
4. Agreed, there is significant lack of "scientific" evidence that it helps, despite plenty of anecdotes to that effect.
Just my stupid thoughts and opinions

Totally with you there bro, go with what feels right 'cos if nobody ever tried anything we'd all still be sat in a bloody cold cave somewhere!

I'm just waiting until somebody completes a controlled grow off with 2 Indica clones in identical environment with and without UVB and shows a bigger THC yield than the same watts spent on red/blue/white light. Sounds pretty demanding of me I know.

I'm just completely non green fingered, biology has always been magic to me until I can understand it through chemistry and physics so with that in mind I had to start growing in a completely clinical, scientific manner.

I've always understood the big picture that we're trying to recreate a years growing in roughly three months in a controlled indoor environment.

I think it's kind of sadly ironic that so many of us on here achieve this "miracle" of 4 harvests in a year with relative ease to get a few ounces of harmless smokes that we could grow outside if it was legalized while others still starve because they are lucky to manage one subsistence crop a year.

(Sorry for going off on a moral tangent but I've got an old tent sitting round and I've been trying to figure out a way of taking the roof off and using the (African?) sun as a light and the reflective material to let people grow the smaller highly nutritious food crops faster. Can you imagine CannaTentAid?)

Anyway, that "perfect" outdoor environment we create seems counterproductive to what the plants have evolved to deal with. It raises a couple of points I've never quite had satisfactory responses to;

1. Why do none of our grows simulate the (equatorial?) daily sun cycle we are trying to recreate, i.e. the sun rises to one side of the plant and passes overhead to the other side before setting. I can understand using full strength lights all of our simulated daytime but why on earth(pun) do we not have systems available to provide the progressive directive coverage of sunlight?

Our lights are static and the sun isn't so that's the opposite of how the plants have evolved to absorb the maximum light in the most efficient manner daily.

2. This leads me to a very controversial subject, defoliation. I don't want to re-open the debate between the two camps. We can take it that all plants evolve mechanisms to deal with real world problems, animal grazing of leaves causing smellier/bigger buds isn't that much of a stretch but I feel that combined with our static lighting it adds weight in favour of some form of defoliation if only to allow the sunrise/sunset light to get through to the lower areas as the plants metabolism expects.

Both of these points are unproven, the first is speculation on my part and the second is well debated. I have to admit I want to defoliate but don't because it's unproven and I haven't figured out a way to make my lights move on an automatic pulley system, yet!