Ultra Violet Lighting(Black Light)

hey guys n` gals, I have a question which i would like answered, as it`s been annoying me all day,so here goes, "does ultra violet light benefit MJ whilst indoor growing?
The reason i ask is that i have one of these lights.As it is "far left" in the spectrum, i wondered if anyone has tried using this type of lighting, in conjunction with other cfl`s or my 400w HPS.
Any thoughts on the matter are very :welcome: :fly: :fly: :stoned: cheers for all feedback, Shuggy.

Uv rays can produce more resin. I don't know about a blacklight but I think the ones used for lizards will give you the desired results. Btw, don't go to high on the wattage...they get HOT!

thanks alot dude:48: :stoned: :aok:

You know, I've really been wondering about this myself. I can recall a really random memory from years ago when I saw this house and up in the window they had a black light that caught my attention. The blinds where open and from the street outside I could see they had plants growing under it. So I guess you must be able to grow under it because that persons plants were definitely growing from the looks of it. Don't take this for certain though.

I recommend that you still use CFLs or your HID and add the UV light to that.

Here is some extra info on UV lights you should be aware of.

Ultravoilet lighting: lamps and light bulbs


We have all heard of ultraviolet light bulbs, but very few people understand what ultraviolet means. Ultraviolet is not visible to the human eye and many people don’t know this, but UV is radiation. Light is measured in nanometers and UV light (ultraviolet light) has 3 different nanometer measuring. UV-A is measured from 320 nm to 400 nm. UV-B is measured from 280 nm to 320 nm and UV-C is from 100 nm to 280 nm.

Of the three types of ultraviolet lighting UV-C is a proven form of sanitation. Also known as Germicidal Irradiation, UV-C is used to purify air, water, and surfaces. These types of ultraviolet lamps kill germs, and such bacteria as fungi, mold and spores. It also kills allergy causing elements and germs that trigger asthma. These UV bulbs are able to do this because of their short wavelength. The UV-C penetrates the outer membrane layer of bacteria, viruses, etc. After the UV-C penetrates the membrane it attacks the target DNA and breaks the chain between the two helixes, ultimately leaving the germ or bacteria dead.

UV-B is similar to the ultraviolet light that the sun emits. Class B ultraviolet bulbs can be found in tanning salons. However UV-B can cause some health issues if exposed to it for a long time. Be careful not to be exposed to class-B ultraviolet lamps.

Class-A ultraviolet lights are commonly known as black or blue lights. Its nanometer rating lays between 315 nm to 400nm. This ultraviolet lighting is generally none harmful. It’s a reasonable source for tanning though it’ll take a much longer time to achieve wanted results.




Obviously UV-B would probably be the best if you're trying to replicate what the sun provides. If you use a UV-B you will need to be careful about being exposed to it. It can harm your skin and your eyes. You could always just turn it off when you go to take care of your plants though. But if what was said is true about boosting resin production, then I might consider using one.

yeah i think i will give it a shot and i`ll keep all informed through my grow journal. i think i`ll go with alternating 24hr periods of my high intensity cfl`s,then swap 1 of the cfl`s for the "UV" light.That`s the plan.....
unless someone else jumps in and says it`s pointless,or not trully "benneficial". thanx for the feedback folks, greatly appreciated man,
cheers.:48: :stoned: :48: :fly: :fly:

iv read in one of those MJ cultivation books that turning on black light in dark periond will make yeild little bigger never tryied but that what it say

just not too much of blak light one 40 watt fluor per plants

i`m just going to use 15w light per plant on the "UV", that should be enough to see through the grow,and any "benefits" that may come with it.
cheers:fly: :stoned: :fly:
it`ll be a nice experiment to do man,i`ll keep you all updated

Heres a lil info...it seems uvb converts cbd to thc!!!!-(5) "Pate (1983) indicated that in areas of high ultraviolet radiation exposure, the UVB (280-320 nm) absorption properties of THC may have conferred an evolutionary advantage to Cannabis capable of greater production of this compound from biogenetic precursor CBD. The extent to which this production is also influenced by environmental UVB has also been experimentally determined by Lydon et al. (1987)."

The author's own experience allow for a more specific conclusion: If the UVB photon is missing from the light stream(a), or the intensity as expressed in µW/cm2 falls below a certain level(b), the phytochemical process will not be completely energized with only UVA photons which are more penetrating but less energetic, and the harvested resin spheres will have mostly precursor compounds and not fully realized THC(c).

(a)Examples of an environment where the UVB photon would be missing from the light stream include all indoor cultivation illuminated by mercury or sodium lamps and in glass, polyethylene or fiberglass covered greenhouses.

(b)"The maximum UVB irradiance near the equator (solar elevation angle less than 25 deg.) under clear, sunny skies is about 250 µW/cm2. It was observed that the daily solar UVB in Riyadh, Saudi Arabia (N24.4Lat.) decreased from September to December by about 40% (Hannan et al. 1984)." The further a person is from the tropics, the less UVB radiation there is: the average annual exposure of a person living in Hawaii is approximately four times that of someone living in northern Europe. "Some reptiles, mainly lizards, turtles, tortoises and crocodilians, require UVB to make vitamin D3. Green Iguanas will start to show signs of metabolic bone disease at 6 months of age if not exposed to UVB wavelengths. A rubber jaw, shaking and non-use of hind legs are all signs of metabolic bone disease. Metabolic bone disease is perhaps the most common nutritional deficiency affecting captive reptiles. UVA and UVB wavelengths help to prevent or reverse this disease which is commonly seen in young captive lizards; these wavelengths also help to increase appetite and activity in lizards and turtles who require more UVA and UVB than pythons and snakes to induce reproductive behavior. Even though snakes get their vitamin D3 from the livers of the animals they eat (mice, rats, etc.), snakes and amphibians benefit from the UVA wavelength." Below are some UVB readings taken in Hoyleton, Illinois, on a clear sunny day in June by David Krughoff as reported in Reptile Lighting 2000.

7am: 12 microwatts/cm2
8am: 74 microwatts/cm2
9am: 142 microwatts/cm2
10am: 192 microwatts/cm2
11am: 233 microwatts/cm2
12pm: 256 microwatts/cm2
1pm: 269 microwatts/cm2
2pm: 262 microwatts/cm2
3pm: 239 microwatts/cm2
4pm: 187 microwatts/cm2
5pm: 131 microwatts/cm2
6pm: 61 microwatts/cm2

And more-Many plant species are able to acclimate to changes in ultraviolet-B radiation (UVB) (290-320 nm) exposure. Due to the wide range of targets of UVB, plants have evolved diverse repair and protection mechanisms. These include increased biosynthesis of UVB screening compounds, elevated antioxidant activity and increased rates of DNA repair."-uvb screening compound of marijuana=resin.

I wonder if one UVB tube would do the trick. Any idea as to how much they should be exposed to for best resin production?

Nope...i'd say this is experimenting.

Ive used black lights on sick plants. they seem to perk up really fast.