# UVB lighting late in flower



## bob harris (Feb 9, 2011)

I've heard the stories of increased trich production from uvb lighting, and decided to run a "test".

The strain was flo..4 cuttings from the same mother, 600 watt hps flower..co2 up until final 2 weeks. When I turned off the co2, I set up 2, hanging 23watt 10.0 uvb bulbs, with round reflectors over 2 plants (one side of the grow chamber) The reflectors were directly over the "test" plants and did not reach the "control" plants. 

Started the uvb on a separate timer. 15 min per hour to see how the girls reacted. It became apparent within 2 days (moving the 15 min to 15 on 15 off...then 45 on 15 off) that they weren't bothered at all by the uvb. 

As a matter of fact, they seemed to "like" it. But whatever you want to call it, they responded by producing noticeably more trichs than the other side of the room. The yield form the "uvb" plants and the non uvb side was equal. So, no weight increase..just light, fluffy, snow...

Fairly inexpensive to set up, just wondering if anyone has played with uvb, and if you saw result...


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## NoCeilings (Feb 9, 2011)

did you notice any difference in smoke or the high?


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## bob harris (Feb 9, 2011)

NoCeilings said:


> did you notice any difference in smoke or the high?


Yes..the flavor and smell became "hashier" and the potency was...enhanced noticably over the plants without the uvb.

Under 100x magnification..the effect was amazing. The buds without were very nice, don't get me wrong. But the buds that had UVB, under a scope, you could just see more...layers..of trichlomes. They were simply everywhere. 

After a one month cure, the buds though "crispy" to the touch, still contains the "essential oils" of the plant. Best to grind, then let sit a minute before burning. I just like the strain I guess.


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## legallyflying (Feb 10, 2011)

Kudos for doing a side by side test. I have read many threads about it but nobody performed many side by sides. I am curious as to which light you were using. From what I have read, many of the florescent UVB bulbs gave off little to no UVB (in relation to how much the sun puts out). I was looking at the mega ray lizard bulbs as they put out a shit ton of UVB... Like don't go in the room when it's on levels. 

Do you have any pictures of the different buds?


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## RawBudzski (Feb 10, 2011)

which is why im keeping my 600w MH over my flowers


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## bob harris (Feb 10, 2011)

RawBudzski said:


> which is why im keeping my 600w MH over my flowers


MH will give you some uvb...and 600 watts is some MH. I, unfortunatly don't have an mh bulb I veg under t5's, then go to hps for flower

Iv'e heard that using MH and HPS in flower also helps the overall "health" of the plant..did you notice more "vigor" under both types of lighting?.


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## bob harris (Feb 10, 2011)

legallyflying said:


> Kudos for doing a side by side test. I have read many threads about it but nobody performed many side by sides. I am curious as to which light you were using. From what I have read, many of the florescent UVB bulbs gave off little to no UVB (in relation to how much the sun puts out). I was looking at the mega ray lizard bulbs as they put out a shit ton of UVB... Like don't go in the room when it's on levels.
> 
> Do you have any pictures of the different buds?


I used 10.0 uvb rated, 23 watt cfl lizard lights. Bought them at Petmart. My understanding is the "10.0" are the strongest uvb lizard lights...though they certainly get bigger than 23 watts. According to the box, the uvb penetration is 20 inches. Very little to no heat produced by the bulbs..

Yea. they made my eyes feel funny if I looked at them. I unplugged them from the timer when I tended the garden, but it's hard not to "check and see if they are on" when you first fire them up. 

My camera won't focus in close enough for a trich picture. You can definatly see the difference under a scope however. Considering how much equipment and lighting cost to begin with..adding uvb was fairly inexpensive. About $40 per fixture, and the bulbs will go alot of hours. 

I have a legal medical grow..and am limited to 12 total plants. I only flower 4 at a time. (4 in flower, 4 in veg and 4 "rooting") that more or less gives me a "perpetual" grow...Different strains may react differently as well...but with Flo, the results were worth the effort. Increased trich production became apparent after the second "night" cycle. Seems they produce the trichs as "sunscreen' to protect themselves from the uvb. Interestingly, even the fan leaves and stems showed much more trich development than the plants without uvb. (handy for any "hash makers" out there.) 

I'd say it's worth a try for anyone, assuming that your grow room is "tweaked". IE: plenty of light, co2, temp control etc etc are well managed. I'd recommend getting all you other "environmental" conditions optimal before playing with the uvb..Like anything else, I'd also recommend starting the uvb slowly, until you see how your strain reacts. Build up exposure time slowly, start with the uvb farther from the plants, until you see what your ladies like.


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## gargantuanganja (Feb 21, 2013)

I'm about to try this myself.


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## Malevolence (Feb 21, 2013)

Do you run uvb 12/12?


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## cannawizard (Feb 22, 2013)

You can run UVb on 12/12 if you wanted


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## yesum (Feb 23, 2013)

I use a similar bulb or the same one, Reptisun cfl 10.0. You will want to keep the plants 3 to 5 inches away from the bulb as the measured uw is over 500 at 3 inches. At around 10 or 12 inches from the bulb the uw falls to about 150, which is the low end of effective uw. This is without a reflector, bulb hanging vertical in center of grow.

My plants were all very frosty but I think the uvb does more to the profile of the resin glands than it does to make more of them. Creeper high, stronger high, trippier, more complete and longer lasting buzz are some of the effects you might notice.

I ran the uvb bulb for the last 45 days of flower for several hours each day.

The mh or cmh lights produce a tiny amount of uvb which is not helpful imo. Looking at the uvb bulbs without uvb blocking sunglasses is like looking at the sun. I turn the uvb light off when working in the grow.


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## 3 Pounds of Weeden (Mar 20, 2013)

No bulb will ever outdo the sun. Put as much UV/B in as you want.


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## Mookjong (Mar 20, 2013)

3 Pounds of Weeden said:


> No bulb will ever outdo the sun. Put as much UV/B in as you want.


The problem is getting that big ass thing in the house.


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## RL420 (Mar 22, 2013)

Mookjong said:


> The problem is getting that big ass thing in the house.



lmfao, that ended up being really funny for some reason.


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## 8deez8 (Mar 23, 2013)

I use UVB as well and am convinced of its effectiveness... however,... for science sake... it is quite possible that because he was using only HPS that the increased vitality of the bud may have been from the added blue spectrums coming from the other 90% of the pet lamps output.. activating different PS pathways... for example...
grow room with only HPS...add to one side a few 6500k CFLs... no UVB... the side with the 6500K cfls will have higher quality bud. especially sativa dom varieties. 

WE could throw hypothesis at it all day. My guess is that the UVB did add some benefit along with the benefit provided by complimentary blues, etc...
UVB tests done with CMH/CMH+UVB would give better data as to effects of UVB, IMO.


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## PurpleBuz (Mar 23, 2013)

All of the UVB reptile bulbs that I know of have significant amounts of light in the UVA and the actinic blues range (400 - 450 nm).
so yes I agree its hard to know how much of the effect is stricty because of the UVB, versus other Blues.


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## polyarcturus (Mar 24, 2013)

PurpleBuz said:


> All of the UVB reptile bulbs that I know of have significant amounts of light in the UVA and the actinic blues range (400 - 450 nm).
> so yes I agree its hard to know how much of the effect is stricty because of the UVB, versus other Blues.


i use MV bulbs i can tell you that UVB is very effective.


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## cannawizard (Mar 24, 2013)

PurpleBuz said:


> All of the UVB reptile bulbs that I know of have significant amounts of light in the UVA and the actinic blues range (400 - 450 nm).
> so yes I agree its hard to know how much of the effect is stricty because of the UVB, versus other Blues.


From what I have read, blue spectrum does have positive effects on floral growth of cannabis, I'm not sure if UVA has any studies on it yet pertaining to its effect on cannabis' overall growth (unless someone has something, by all means please link the sources)~


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## polyarcturus (Mar 24, 2013)

cannawizard said:


> From what I have read, blue spectrum does have positive effects on floral growth of cannabis, I'm not sure if UVA has any studies on it yet pertaining to its effect on cannabis' overall growth (unless someone has something, by all means please link the sources)~


i forget where i read it but there is an article somewhere(im looking) that states the reactivity in the production of essential oils, on terms of both the energy of light and the percentage of oil production. UVa was something like 20% less effective. and 420nm-460nm was like 15% down to 5% as effective as UVb in terms of oil production for the amount of light it took and the energy needed to create the light.

sorry dont mean to not have much more that, other than ive flowered under all these said conditions and UVb visibly had the most effect. i am actually more thoroughly testing the blue light conditions now, as i have paired a t5 with 10000k bulbs and an HPS the frost has been pretty good, comparable to the UVB but not quite the same.


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## cannawizard (Mar 24, 2013)

polyarcturus said:


> i forget where i read it but there is an article somewhere(im looking) that states the reactivity in the production of essential oils, on terms of both the energy of light and the percentage of oil prosecution. UVa was something like 20% less effective. and 420nm-460nm was like 15% down to 5% as effective as UVb in terms of oil production for the amount of light it took and the energy needed to create the light.
> 
> sorry dont mean to not have much more that, other than ive flowered under all these said conditions and UVb visibly had the most effect. i am actually more thoroughly testing the blue light conditions now, as i have paired a t5 with 10000k bulbs and an HPS the frost has been pretty good, comparable to the UVB but not quite the same.


Good info~ I'm with you on the UVb, it's pretty much been the main focal point of my personal research & experiments~ btw, have you seen any studies or footnotes concerning UVb exposure leading to more CBD% (for CBD strains)-- the enzymatic processes that happen in that tiny sphere(trichomes) is mind bogglin' hehe


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## polyarcturus (Mar 24, 2013)

cannawizard said:


> Good info~ I'm with you on the UVb, it's pretty much been the main focal point of my personal research & experiments~ btw, have you seen any studies or footnotes concerning UVb exposure leading to more CBD% (for CBD strains)-- the enzymatic processes that happen in that tiny sphere(trichomes) is mind bogglin' hehe


no, actually i haven't in fact ive heard UVB increases thc-v the most. i have to agree, i have a few pet projects, but one mother strain i work with is extremely psychedelic.(love taking a nap after smoking it) with the UVB added the psychedelic effects have definitely increased.

s far as cbd production i believe this to be more of a pure genetics thing unaffected by outside factors other than the health and overall vigor of the plant. but what ive been wondering, besides testing, if there is a visible feature, that allows you to "measure" your CDB content. in other words does the content of CDB effect the shape and size of trichomes. from what ive seen from my pet project, that i believe to be high in CBD( reason i believe this, lets keep it simple, smoke is not that great, tastes or high, its very sleepy and tired buzz. obviously i have no way of testing) trichomes that form on high cbd plants tend to have a smaller stalk, and smaller size heads in general. i have experienced this effect with many shit bag seed plants but alas no way of proving. 

but anyways back to Uvb and CBD, no i dont think there is any correlation unfortunately.


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## PurpleBuz (Mar 24, 2013)

polyarcturus said:


> i forget where i read it but there is an article somewhere(im looking) that states the reactivity in the production of essential oils, on terms of both the energy of light and the percentage of oil production. UVa was something like 20% less effective. and 420nm-460nm was like 15% down to 5% as effective as UVb in terms of oil production for the amount of light it took and the energy needed to create the light.
> .


hope you can find that article. Makes sense that as you move away from UVB the effect would diminish.


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## 8deez8 (Mar 24, 2013)

polyarcturus said:


> .... if there is a visible feature, that allows you to "measure" your CDB content. in other words does the content of CDB effect the shape and size of trichomes.
> 
> but anyways back to Uvb and CBD, no i dont think there is any correlation unfortunately.


I will say that too much UVB late in flower will cause the trichomes to go amber prematurely. Just speculation here but I am pretty sure that amber trichomes have more degraded THC and therefore more CBD.
I always pack on the UVB early in flower and taper off as the plant matures. To demonstrate what I am referring to-- take a maturing bud ~1-2 weeks from harvest and put the UVB too close to it. It will go amber within several hours. powerful stuff.


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## polyarcturus (Mar 24, 2013)

yes it will cause some trich to amber early but this does not mean the bud is done.

THC degrades into CBN, not CBD. i just learned that myslef so dont feel too bad

i use UVB 12/12 entire time at full strength regulating the exposure and time is unnatural, UV rays re emitted all day by the sun and like i said just cause hairs are red and trich are amber, if that buds still fluff it aint done.


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