I think it's finally officially common knowledge that marijuana plants don't like UV-B light. Fortunately, their natural defense against UV-B light is to produce resin glands. My question is, when do you use the UV-B lighting, (flowering, veg)? How long do you leave it on at a time? How much UV-B light is too much? Anyone that has any experience using UV-B, your opinion is much appreciated.
Ok well I had never heard of it being used before (I am on my first grow) and I thought it was truly a genius idea. What color temp/wavelength are you using? Because time of exposure should be determined by wavelength. The shorter the wavelength is the more damaging affects the light will have on your plants--you follow? I am going to get a bulb with around 310nm because it is right in the middle of the UV-B scale (i dont want to severely damage my plants nor do I want to waste to much electricity) and just play around with it until I find a good time exposure. I feel like UV-B radiation will have a pretty quick affect on resin production (anywhere between immediately and a day after exposure). If I were you I would give it a 1/2 hour of radiation at first and then carefully examine your plant for any changes. Slowly increase length of exposure until you get the results your looking for. Good Luck and thank you for introducing me to this practice.
I think this is abit of a fallacy actually. Cannabis plants developed Resin glands, over millions of years through evolution, to be a defence against UV radiation. It's not like they're regulated on a daily basis in response to outside conditions, and the reson glands arent all going to fall off, or fail to apear at all, if you grow indoors or in a cupboard where there no UV light availible at all to "stimulate" the plant. Finally, UV has absolutly no relevance to PAR, or "Photosynthetically active radiation", which is really all your plant cares about when its going its power to grow. If anything i think suplimenting your grow lights with UV (or infrared) is probably less benificial to your plant than good.
I think that you are right about certain things but for the most part flat out wrong.* "It's not like they're regulated on a daily basis in response to outside conditions" But of course resin is regulated on a daily basis, it wouldn't make sense not too. It would be an enormous waste of energy to continually produce resin even if the plant didn't need it. On the flip side, if there was a set level of resin production like you indirectly suggest, then what would happen if one summer UV-B spiked? Most plants would die unless they could produce extra resin (mmm wouldn't that be a nice field to stumble across). Evolutionarily, natural selection would favor individuals who could regulate resin production, thereby balancing utility with economics. I am going to make a parallel here between cannabis and people. People have developed the ability to produce melanin, which darkens skin (skin tan) to protect from UV rays. However this only happens when we are exposed to UV radiation. Will a swede ever have dark skin if he is never exposed to UV radiation? But will he darken if stranded on a pacific island? Of course in some populations where radiation is always a threat, high melanin levels have been pre-programed from birth but that does not mean that melanin production is still not a dynamic process. And this is probably true for cannabis as well (Malawi Gold for instance). And one other thing, although you are correct about UV not being within PAR, this radiation has always been present during cannabis' evolution and so in order to mimic outdoor conditions accurately, one must use these rays--unless you know of every function that occurs within the plant can you be safe not using UV-B...(humans obviously dont photosynthesis but UV-A radiation does produce vitamin D which is vital so you never know what your plant might need). *I do realize my argument has an achilles heel. Cannabis is a seasonal plant--it is possible, although (I think) unlikely, that because these plants are not meant to survive more than half a year they might not need a regulation system if there was enough diversity within their population with regards to set resin production levels. In this scenario there would be some plants that put out a little resin (these plants would be favored during times of less light and nutrients) some plants that put out a medium amount of resin (these plants would be most common) and some plants with enormous resin output (these plants would be favored during a very intense summer). In this way there would be resin regulation within the entire population instead of the individual and it would ensure the survival of the pop. regardless of UV fluctuations. You might find the first part of my thread interesting: http://forum.grasscity.com/advanced-growing-techniques/508951-hunt-best-bulb-bring-sun-inside.html
I know you want an answer now but just thought id let you know I am going to buy a UV-B reptile lamp and do some experimenting. Expect some pix in about a month... has anyone ever tried this with some good uv-b lighting?
do it closetgrower!! When i start flowering my plants in about a month, i'm gonna get 3 or 4 reptile lights and use them about 4 or 5 hours a day. Unless someone on here say otherwise by then. think of it like a ginger kid getting a sun tan. If i had to bet, i'd say it's not only gonna make bigger resin glands and more of them, but it's gonna make your overall bud size bigger (or more dense). We'll see.
it's under the sick plants category right now. http://forum.grasscity.com/sick-pla...-dwc-grow-whats-wrong-my-plants-pictures.html This is my first grow, and i finally got it close enough to "ideal conditions".
Im also very interested in lightning times / strength of the lamps Im thinking about getting a CFL Lamp around 15-20W to test it myself, but im very unsure in the times to light it. In some places nothing is mentioned that they used it other then the normal light, in others i have read something about 5-10mins per day to not harm the plant. btw so no one can say Universities arent doing anything useful: Energy Citations Database (ECD) - - Document #6696642 over 30 years old but still good
Didnt found a way to. Ive also looked if i can find contact Information on the Person that publicised it with no luck :/ Would be very interesting how exactly they lightened it with UVB and how much higher the THC Concentration has been. As its written there it could also be that its only like 1-2% increase which wouldnt be worth the effort
that was a really good find. I suppose im going to stop by the library after my exam and see if they can locate it for me.
logically it would make sense to use the UV-B to grow the same strain over and over, cloning from the strongest female. That way you genetically train that plant specifically to be accustom to heavy UV-B, producing more and more resin every time you re-grow it.
that is very true but that also implies that if i havent already i have to find an extremely resinous set of genetics. Im actually looking into this to boost the genetics that i find so near and dear to me now! so i will hope that i can improve resin production from the mother. Although im very happy now im just trying to improve this strain.
I dont think that does work, if you clone it over and over, it wont change the genetics of the plant. What you would need to do is get it fertilized, seed some hundred new plants that you grow under UVB and the redo the same over and over again with the strongest plants.
wait. so if I have a mother plant that has been UV-B'd during flowering; it buds; i harvest; clip some clones; grow those clones; UV-B them during flowering; they bud; i harvest.....etc...etc...etc. you don't think that, that plant will train to have very heavy resin concentration?