I was doing a Google search on something and stumbled upon an old thread here that had some discussion about UV light. Some people were very fast in there belief that UV has no effect on plants, well others, one even said Ed Rosenthol claimed that UV light would increase potency.

For some reason this debate seemed to stop inconclusively. I am new to this forum and apologize if the topic has already been brought back up and I am just unaware of it.

However this is a very interesting topic. So, what are your ideas? Do you have any information regarding the effects of UV light on cannabis growth or potency? Lets get that debate rolling again.

I have found this information (extracted from http://www.cannabisculture.com/articles/2696.html):

A researcher conducted a controlled experiment in a greenhouse. He lit a group of high potency plants similarly except with the addition of UVB light to some groups. He found that the percentage of THC increased in a direct ratio with the increase in UVB light. This research confirms the adage that high altitude plants are more potent than those grown at low altitudes.
If you look at old-world land races of cannabis, plants that have become adapted to the climate and latitude, the ratio of THC to CBD starts at 100 : 1 at the equator. At the 30th parallel (The Hindu-Kush Valley) the plants have a ratio of 50 : 50. At the 45th parallel the ratio is near 1 : 100. This corresponds roughly with the amount of UVB light received at these latitudes. There is much more UVB at the equator than the 45th parallel.
How can you get more UVB light to your plants? Certainly it's true that MH lamps emit more UVB light than HPS lamps. Still the amount that MH lamps emit is small. In fact, many manufacturers use UVB shielding glass to filter out most of the UVB that's produced. The UVB light the plant receives from an MH lamp does increase the plant's potency slightly at the cost of yield, but there are better ways to introduce UVB light into the grow room. They include reptile lights, which emit about 10% UVB, and tanning lamps.
The problem with using these lamps is that they are associated with increased number of cancers and many other problems. They should not be on when you are in the grow room. Not much research has been conducted on using them to produce higher THC values. I will do a full report in a future issue.

yo mon - check it -> 10.0 uvb light

i use them, and i'm gonna double up for the next flowering cycle...

This is an important piece of info!

It is assumed that THC is produced to protect the cannabis from herbivores. It also has been discovered that the crystals block UVB 275nm - 325nm range - the most harmful part of the electromagnetic spectrum.

Im no science wiz but it seems logical that any plant with these features might just produce more trichomes if threatened by UVB

Low presure mercury vapour lights (flourecent) have a coating on the inside of the tube to convert UVB into less harmful wavelenghts.

Im going to elevate the UVB on a few on my flowering girls. YIK!

Stay tuned!

Why did this thread die? This is a very interesting idea.
Are there any new discoveries about UV lights and canabis?

nice thread, i read some were that grew at i higher elevation were more potent but yeilded less then the plants that grew at a lower elevation...

There are some very lengthy threads and info on this if you do some searching around

The whole LED area is new to all of us and it's important cause it would cut our electricity by $$$ not cents. We just need more data to be proved that if works.

I saw a study that showed that plants grown with maximum UV were only about 25% more potent than ones with no UV at all. This proves that UV is not required for decent potency (as LED growers would know) but does make a little bit of difference. Since the UV is also dangerous to the grower, I would stick with normal lights myself but an extra 25% potency might be worth it to some people.

looks like the UV topic has been taken on at another thread heres the link. Great info!
Thanks.

http://www.rollitup.org/advanced-marijuana-cultivation/96571-10-0-uvb-light-new-post.html

ONLY 25%!?!?!?!?!?!?! Make a little bit of a difference?

Who doesn't want an extra 25% potency?

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