UV A And UV B In Late Flower

Skunk Baxter

Skunk Baxter

Well-Known Member
This is something I've wanted to try for years, and I think I may give it a go with this grow. Today begins Week 9 for a White Rhino SOG in coco, and I still have almost all clear trichomes and some buds are still sprouting fresh new white pistils. I figure I have a good two weeks left for most of the plants, although a few look like they're in their last week (I'm growing from seed, and have several different phenos).

At any rate, I'm thinking of hitting them with UV light the last couple of weeks. Never having done it before, what suggestions do y'all have? It's a 4.5 X 4.5 tent, with a 1K Superthortilux bulb. Would I just hang several fluorescent fixtures on the edges of the tent ceiling, and put UV tubes in them? How many, and what size would be best for a 4.5 X 4.5?

Thanks in advance, everyone.
 
DankaDank

DankaDank

Well-Known Member
DankaDank

DankaDank

Well-Known Member
RM3 said:
I run UV the whole grow, yeppers even seedlings, it is after all what they get outside.

Reptile bulbs are not the best option !!! check out the new Agromax UV bulbs
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Interesting haven't heard of them, there's not much info on them but it seems there lights are not uv specific. Do you know what percentage of the light is uva and uvb as well as the penetration ,i know the penetration of the repti sun is 18-24 inches from the light (excluding the reflector) which is pretty darn good IMO. Why don't you like the reptile lights ? have you used the one's i previously mentioned?
 
RM3

RM3

Well-Known Member
DankaDank said:
Interesting haven't heard of them, there's not much info on them but it seems there lights are not uv specific. Do you know what percentage of the light is uva and uvb as well as the penetration ,i know the penetration of the repti sun is 18-24 inches from the light (excluding the reflector) which is pretty darn good IMO. Why don't you like the reptile lights ? have you used the one's i previously mentioned?
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There is a bunch of info, and they are the only bulb (thus far) with proper %'s of UVB & UVA

https://www.htgsupply.com/Product-AgroMax-4ft-T5-Pure-UV-Bulbs

As to why I don't do reptile lights it is because I had a friend with a $6000 UV meter that tested bulbs, surprisingly there were very few that did what we need
 
S

shloppyjoe

Well-Known Member
RM3 said:
There is a bunch of info, and they are the only bulb (thus far) with proper %'s of UVB & UVA

https://www.htgsupply.com/Product-AgroMax-4ft-T5-Pure-UV-Bulbs



As to why I don't do reptile lights it is because I had a friend with a $6000 UV meter that tested bulbs, surprisingly there were very few that did what we need
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Very cool info! I've also been thinking about adding these bulbs. What kind of meter cost 6k! I would be interested in this meter. I'm also curious how many I would need for 17x17 grow.

Also wondering if I should run in both veg and flower and for how long?
 
BobCajun

BobCajun

Well-Known Member
Skunk Baxter said:
This is something I've wanted to try for years, and I think I may give it a go with this grow. Today begins Week 9 for a White Rhino SOG in coco, and I still have almost all clear trichomes and some buds are still sprouting fresh new white pistils. I figure I have a good two weeks left for most of the plants, although a few look like they're in their last week (I'm growing from seed, and have several different phenos).

At any rate, I'm thinking of hitting them with UV light the last couple of weeks. Never having done it before, what suggestions do y'all have? It's a 4.5 X 4.5 tent, with a 1K Superthortilux bulb. Would I just hang several fluorescent fixtures on the edges of the tent ceiling, and put UV tubes in them? How many, and what size would be best for a 4.5 X 4.5?

Thanks in advance, everyone.
Click to expand...
With UVB, you should bear in mind that it will reduce growth and yield significantly, but will increase secondary plant product production, meaning cannabinoids in this case. That's why I wouldn't use it in veg stage or early flowering. Until there are flowers in place, what would be the point? All you would get is reduced growth. I use CFL desert reptile bulbs, tropical are too weak.

I start them when significant buds are forming, like 4 weeks, and I start with low wattage 13w ones and go to 26w the last 2 weeks, 2 bulbs in 1.5'x3' cabs. I mistakenly bought the tropical ones first time, and only 13s because that's all I could find locally at the time, so now I'm trying it with desert ones and 26w the last 2 weeks. The 13w tropicals didn't do much, though it did seem somewhat more potent, just not substantially. Their UV output is way lower than the desert ones, practically none.

This is only the second batch I've used UVB on so I can't tell you yet how it will turn out with the upgrade. If it doesn't make a big difference this time, I'm out, because they're just too expensive and have a very short useful life, 6 months to a year.
 
whitebb2727

whitebb2727

Well-Known Member
BobCajun said:
With UVB, you should bear in mind that it will reduce growth and yield significantly, but will increase secondary plant product production, meaning cannabinoids in this case. That's why I wouldn't use it in veg stage or early flowering. Until there are flowers in place, what would be the point? All you would get is reduced growth. I use CFL desert reptile bulbs, tropical are too weak.

I start them when significant buds are forming, like 4 weeks, and I start with low wattage 13w ones and go to 26w the last 2 weeks, 2 bulbs in 1.5'x3' cabs. I mistakenly bought the tropical ones first time, and only 13s because that's all I could find locally at the time, so now I'm trying it with desert ones and 26w the last 2 weeks. The 13w tropicals didn't do much, though it did seem somewhat more potent, just not substantially. Their UV output is way lower than the desert ones, practically none.

This is only the second batch I've used UVB on so I can't tell you yet how it will turn out with the upgrade. If it doesn't make a big difference this time, I'm out, because they're just too expensive and have a very short useful life, 6 months to a year.
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Bull shit. Uva or uvb neither reduce yield or growth.

Have you seen outdoor plants? They get a lot of UV. More than we can replicate with bulbs. Plants get to be monsters outside.
 
testiclees

testiclees

Well-Known Member
after running the UVB on a few strains (arcadia t5) I think maybe UVB affects each strain a little differently. Also I dont think it's as simple as saying it makes the bud "more potent". I wonder if the UVB stimulates particular psycho active compounds but not evenly and not all of them.

This bud had quite a bit of UVB through flowering period.midnight mass spring.jpg
 
Skunk Baxter

Skunk Baxter

Well-Known Member
testiclees said:
after running the UVB on a few strains (arcadia t5) I think maybe UVB affects each strain a little differently. Also I dont think it's as simple as saying it makes the bud "more potent". I wonder if the UVB stimulates particular psycho active compounds but not evenly and not all of them.
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That's a very good guess, IMO. 30 years ago, everybody thought it was all just about the THC, and 10 or 15 years ago everyone thought it was just THC and CBD. It's only relatively recently that we've become more aware that there are a lot more alkaloids at work in cannabis, and that they all work together in a delicate, sophisticated, and incredibly elaborate and complex harmony. I often wonder how much more we'll know about the whole spectrum of the plant's chemistry 10 years down the road - how many more alkaloids will have been identified and isolated, and their roles relative to one another more clearly understood.
 
whitebb2727

whitebb2727

Well-Known Member
BobCajun said:
Have you actually read any scientific articles on the subject? Obviously not. You did what's known as "assuming". Try doing a little reading, and some more.
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You are also comparing apple and oranges.

Loss of yield comes from running a mh or other types of bulbs in an all blue configuration. That has more to do with color than UV.

Running UV bulbs mixed with other bulbs of mixed spectrum is the way to go in a t5 and mh/hps combo for his.

Loss of yield is not from the UV.
 
testiclees

testiclees

Well-Known Member
whitebb2727 said:
Bull shit. Uva or uvb neither reduce yield or growth.

Have you seen outdoor plants? They get a lot of UV. More than we can replicate with bulbs. Plants get to be monsters outside.
Click to expand...

I dont know for a fact that UVB can stunt growth but plenty of folks state that it is so. Also, there is a graph on RIU that shows the efficacy of the UVB bulbs and then there's a NASA graph that shows the UVB irradiance at different points on earth. I think just a few t5 12% UVB close to a plant would be more intense UVB than anywhere on Earth.

"This paper reviews growth chamber, greenhouse, and field studies on the effects of ultraviolet-B (UV-B. between 280 and 320 nm) radiation on agricultural crop plants. Our understanding of the physiological effects of UV-B radiation comes primarily from growth chamber studies, where UV-B is artificially supplied via filtered lamps. Both photosystems I and II, as well as carboxylating enzymes, are sensitive to UV-B radiation. Ultraviolet-B radiation also affects stomatal resistance, chlorophyll concentration, soluble leaf proteins, lipids, and carbohydrate pools. In general, the effects of UV-B radiation are accentuated by the low levels of visible radiation typically found inside growth chambers.

Ultraviolet-B radiation has also been shown to affect anatomical and morphological plant characteristics. Commonly observed UV-B induced changes include plant stunting, reductions in leaf area and total biomass, and alterations in the pattern of biomass partitioning into various plant organs. In sensitive plants, evidence of cell and tissue damage often appears on the upper leaf epidermis as bronzing, glazing, and chlorosis." *

Teramura, A. H. (1983), Effects of ultraviolet-B radiation on the growth and yield of crop plants. Physiologia Plantarum, 58: 415–427. doi: 10.1111/j.1399-3054.1983.tb04203.x
 
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