I tried this several years ago. I used a flouro T-5 tube that is 30 inches long UV reptile light, and I read that the UV rays travel 2-3 feet away, so I hung it along the ceiling over the plants, kinda along the side. I started by using it for a couple of hours a day, and increased the time until I saw the damage to the foliage. I settled on 4 times/day for 20 minutes.

The lamp burned out in 3 months, and since I didn't notice any difference in bud quality/potency, I didn't buy a new one.

HTH

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Hey pot'... then why do the most potent strains we know grow in places of high UV?

Very interesting, indeed.

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I tell you this ~ No Eternal Reward will forgive us for wasting the dawn.

Both parts of the spectrum are definitely needed...

I think a number of things.
1. There is an effective radiation pattern_ERP_for every bulb. How the plant orientates to the ERP is the question.
2. As the bulbs age, their effectiveness and probably ERP change.
3. Are there unique ballast and starters for uv bulbs?
4. I still have concerns about the propagation of the waves out into the secondary and beyond harmonics.
5. My opinion_and I'm probably wrong_is that the uv light should as closely as possible mimic the introduction of the uv into the mix. eg, when the sun comes up the level of uv is quite low, only when the suns rays are the most direct to the atmosphere is the uv levels high. It's a bell curve with the max being a 2±hour window for max. uv radiation. This thought goes to my work in progress of a gradual red spectrum moving to a bright daylight spectrum_with uv_ and then back to a red before lights out.
6. I believe that outdoor plants which have been domesticated, have adapted to produce a fruit with less uv. If this is true, then it will take a few cycles before a domesticated dna adapts to the uv. If you look at the areas of high uv, all of the indigenous people are dark skinned.

__________________
I tell you this ~ No Eternal Reward will forgive us for wasting the dawn.

I'm still thinking it's about building a tolerance too. The chemical processes in the plant will need to start getting used to UV very early in the plants life.

They say that the first year of your life is when you learn the most about the world. What would equal a year to cannabis? Once the sprog pokes it's little head out it will get an immediate guage of it's environment... and the chemical processes will start there.

I believe cannabis should adapt just fine.

Here's an interesting cut n paste, prompted by YGF's mention of the moon...

Scientists Clueless over Sun's Effect on Earth

By Robert Roy Britt, LiveScience Senior Writer
posted: 05 May 2005 02:01 pm ET


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While researchers argue whether Earth is getting warmer and if humans are contributing, a heated debate over the global effect of sunlight boiled to the surface today.
And in this debate there is little data to go on.
A confusing array of new and recent studies reveals that scientists know very little about how much sunlight is absorbed by Earth versus how much the planet reflects, how all this alters temperatures, and why any of it changes from one decade to the next.
Determining Earth's reflectance is crucial to understanding climate change, scientists agree.
Brighter outlook?
Reports in the late 1980s found the amount of sunlight reaching the planet's surface had declined by 4 to 6 percent since 1960. Suddenly, around 1990, that appears to have reversed.

"When we looked at the more recent data, lo and behold, the trend went the other way," said Charles Long, senior scientist at the Department of Energy's Pacific Northwest National Laboratory.
Long participated in one of two studies that uncovered this recent trend using satellite data and ground-based monitoring. Both studies are detailed in the May 6 issue of the journal Science.
Thing is, nobody knows what caused the apparent shift. Could be changes in cloud cover, they say, or maybe reduced effects of volcanic activity, or a reduction in pollutants.
This lack of understanding runs deeper.
A third study in the journal this week, tackling a related aspect of all this, finds that Earth has reflected more sunlight back into space from 2000 to 2004 than in years prior. However, a similar investigation last year found just the opposite. A lack of data suggests it's impossible to know which study is right.
The bottom line, according to a group of experts not involved in any of these studies: Scientists don't know much about how sunlight interacts with our planet, and until they understand it, they can't accurately predict any possible effects of human activity on climate change.
Reflecting on the problem
The percentage of sunlight reflected by back into space by Earth is called albedo. The planet's albedo, around 30 percent, is governed by cloud cover and the quantity of atmospheric particles called aerosols.
Amazingly, one of the best techniques for measuring Earth's albedo is to watch the Moon, which acts like a giant mirror. Sunlight that reflects of Earth in turn reflects off the Moon and can be measured from here. The phenomenon, called earthshine, was first noted by Leonardo da Vinci.
Albedo is a crucial factor in any climate change equation. But it is one of Earth's least-understood properties, says Robert Charlson, a University of Washington atmospheric scientist. "If we don't understand the albedo-related effects," Charlson said today, "then we can't understand the effects of greenhouse gases."
Charlson's co-authors in the analysis paper are Francisco Valero at the Scripps Institution of Oceanography and John Seinfeld at the California Institute of Technology.
Plans and missions designed to study the effects of clouds and aerosols have been delayed or cancelled, Charlson and his colleagues write.
To properly study albedo, scientists want to put a craft about 1 million miles out in space at a point were it would orbit the Sun while constantly monitoring Earth.
The satellite, called Deep Space Climate Observatory, was once scheduled for launch from a space shuttle in 2000 but has never gotten off the ground. Two other Earth-orbiting satellites that would study the albedo have been built but don't have launch dates. And recent budget shifts at NASA and other agencies have meant some data that's available is not being analyzed, Charlson and his colleagues contend.
'Spurious argument'
While some scientists contend the global climate may not be warming or that there is no clear human contribution, most leading experts agree change is underway.
Grasping the situation is crucial, because if the climate warms as many expect, seas could rise enough to swamp many coastal communities by the end of this century.
Charlson says scientists understand to within 10 percent the impact of human activity on the production of greenhouse gases, things like carbon dioxide and methane that act like blanket to trap heat and, in theory, contribute to global warming. Yet their grasp of the human impact on albedo could be off by as much as 100 percent, he fears.
One theory is that if humans pump out more aerosols, the small particles will work to reflect sunlight and offset global warming. Charlson calls that "a spurious argument, a red herring."
Greenhouse gases are at work trapping heat 24 hours a day, he notes, while sunlight reflection is only at work on the day side of the planet. Further, he said, greenhouse gases can stay in the atmosphere for centuries, while aerosols last only a week or so.
"There is no simplistic balance between these two effects," Charlson said. "It isn't heating versus cooling. It's scientific understanding versus not understanding."

Here's another...

From the top: The ultraviolet rays that reach the earth's surface come in two basic varieties, the more prevalent UV-A and the more potent UV-B. While each seemingly plays a role in skin cancer and eye damage, it's UV-B that both helps the body produce vitamin D and causes sunburn; its intensity varies widely with time of day, time of year, and latitude. (Being closer to noon, summer, or the equator all = more.) Clouds usually block UV rays, particularly UV-B; on a really overcast day they can keep out 70 to 90 percent of the UV-B coming in.
Maddeningly enough, though, that's not where it ends. Under partly cloudy conditions a phenomenon sometimes called the "broken-cloud effect" can come into play, resulting in higher UV levels than a clear sky would produce, and so a greater risk of sunburn — or worse. A survey conducted at six U.S. sites in 1994 found that cumulus clouds could raise surface UV-B measurements by 25 percent, and in 2004 Australian researchers reported that the specific UV-B frequencies associated with DNA damage were up to 40 percent stronger under somewhat cloudy skies.
Why does this happen? Scientists aren't positive, but there seem to be two key mechanisms here: (1) UV rays bouncing off the sides of dense clouds, and (2) rays getting redirected as they pass through wispier clouds. Conceivably (as an American Scientist article suggested last year), a combination of thin refracting clouds up high and puffy reflecting clouds down low could result in a major UV boost at ground level. Throw in an aggravating factor or two — say, a blanket of snow to knock the rays around some more — and you're on the bullet train to sunburn city.
Also at work is another insidious effect involving haze. Both natural haze and the kind resulting from pollution have a redistributing effect on solar radiation: while they can block UV-B from reaching the earth directly (sometimes reducing overall levels 50 percent or more), they also scatter it all over the place, in effect turning the entire sky into a radiation source. Standing in the open on a hazy day, you may get less UV-B than if the sky were clear (on the other hand, you may not), but over in the shade haze means you'll get lots more — an ominous thought for those dwelling in the smoggier parts of the world. And compounding it all is the problem your friend mentioned, namely that generally people are less likely to take precautions against sun when it's cloudy, leaving themselves wide open to any UV-amplifying consequences.
Crying over spilt milk is lousy public health policy, of course, but it's hard not to feel a little nostalgic for the days when we had a first-rate ozone layer. Ozone's crucial in blocking solar UV-B, hence the widespread dismay on discovering we'd put a big dent in our atmospheric supply. Most authorities agree that ozone depletion has leveled off following decades of fluorocarbon bans, but it'll still take 50 years for the layer to mend — so expect more parasol weather ahead.
And while we're all here: Some will occasionally claim that since the moon reflects UV radiation, staying out too long when it's full can get you a case of "moonburn." In medical parlance, these people are known as half-wits. The moon's only 0.0002 percent as bright as the sun and reflects UV light only about half as well as it does visible light; thus, eight hours of top-strength moonlight delivers less UV-B than a second of sun.

g'mornin' skunk! how are ya? this continues to be wholly instructive. and as with most research....more questions than answers, but to me that is a good thing.

PR - interesting experience. certainly important to bring that into the mix of the discussion. yes Skunk, and the article of chemical ecology of cannabis - although much more theoretical, still suggests that there is a significant role that UVB plays. more to ponder?
this bell curve I believe plays an important role in something like UVB light. thanks YGF. I am totally with you on this. as with an biological organism...its "learning" and "adaptation" begin from day one. I am goning to try and find more to do with seasonal variations in UV radition, and see what relationships have been explored with plant processes....thanks everyone for your incredible contributions to this investigation and thought process.....more and more exciting as the days go by!

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Ride hard, Ride long....git put away Wet each and every time....no holdin' Back.....enjoy the journey ...... cuz that's ALL there is! Walk on and walk tall folks!

this is an "example chart" for the daily max. UV for western Canada..... you know what I find weird OR maybe not so weird....the peak is in June/July....but then again the peak comes from the longest days (June and July)....this means that for AU its prolly similar - except Dec/Jan....which means that in CA....the highest UV is NOT at flowering and budding but during the intial vege growth?

maybe more telling is the UV annual max in Alert, Nunavut - the most northerly community in North America...

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Ride hard, Ride long....git put away Wet each and every time....no holdin' Back.....enjoy the journey ...... cuz that's ALL there is! Walk on and walk tall folks!