Can Blacklights Be Used For Growing?


New Member
Haaaaa sully that blacklights are kewl while smoking a fatty!!!!!!!!! That was good shit!!!! Peace bro.......


New Member
:bong:there good for halloween too, while smokin a fatty of some heavy indica GDP.
then munchin on some candy. hey canna
lets see if strobe lights work on a plant.:popcorn:
.1 sec on/ .1sec off time.


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(if it screws into a regular lamp, it won't produce worthwhile buds). Exception, compact flouro mentioned above)

Check out these led lights thst screw in and flower like a champ:cheer:


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I have a really nice black light and an extra closet... Ill give it a go in a few months when I get this one done and finished. I may do it with a smaller light and to one plant to see, I don't want to try on main crop (can you blame me). But I am always down try new ways and this actually sound legit.


New Member
They can not.
Blacklights do not produce the correct spectrum of light to grow plants.

The only lights that currently produce the required color spectrum of light to grow plants are the following;

Suitable for Growing:

Flourescent (Tube shaped)

Compact Fluorescent
(a flourescent tube with ballast included that screws into regular light fixture)

Metal Halide (MH) Best for Vegetative growth, but it doesn't contain all of the spectrum needed later during flowering for truly outstanding buds. the light shines a blueish/white color

High Pressure Sodium (HPS) Best for Flowering. Ok for Vegetative. shines a yellow/orange color. All can be purchased at your local home/lumber store.

Not suitable for growing:

Blacklight type flourescent lights.

ANY incandescent lamp
(if it screws into a regular lamp, it won't produce worthwhile buds). Exception, compact flouro mentioned above)


Mercury Vapor

Author: Smokey D Dope

Thanks Smokey...!

I've been reading so many different articles and blogs and getting such fine fine detail, but today realized my 3 babies (1st time grower) desperately needed light - whatever i could find/afford ASAP and your above article was the simplest, easiest key guide to the basic facts i needed in a hurry.

Legend - dairy :)


New Member
Ultraviolet (UV) light is an electromagnetic radiation with a wavelength from 10 nm to 380 nm, devided into 3 ranges: UVA from 320 to 380nm, UVB from 290 to 320nm, and UVC from 100 to 290nm.
Black light lamps aint a single kind of lamp. Different brands produce different lamps producing different spectrums with a peak at around 350nm, which is in UVA range except the lamps using MgSrAl(10)O(17)Ce which emit with a peak at 310nm which is in UVB range.
Ultra Violet even in its lighter energy form, UVA, can harm living creatures, so any exposure to UV is not without harm. TO BE TAKEN SERIOUSLY!
That said, the range of UV showing best results on our beloved plant is UVB range. Many commercial producers use peak of UVB for about 30 minutes at the noon time of selected light cycle. Some less expensive setups use low wattage UVB during whole flower light on time with less outcome. Vest outcome can be observed in combining both méthodes at the same time.
The effect is the same as on other creatures, the exposed surface is damaged due to UV and reacts to protect itself from further damage by making more thc containing resin(thc crystals can block UVB effectively). If the exposure is more than required time to trigger the response, damage to the plant can exceed the repair capabilities of a flowering cannabis and will harm your yield.
It is suggested to increase the exposure time gradually untill you reach 30 minutes per day.
Now some about IR, which is included in the light range emitted by some Black Light lamps.(in small densities)Moonlight is high in IR range.
Studies have shown that plants sleep (the photosynthèses slows down and eventually stops, no more co2 uptake from leaf sites and more Oxygen intake in root zones.). Thats why everybody seriouse enough to google abit before setting the timer for first time never uses 24/7 after seedling even for autoflowers. When you switch off the light it takes the plants 2 hrs to stop their rythme and go to sleep. IR exposure reduces this time dramaticaly to few minutes. So for any photo IR sweeping at the beginning of dark cycle is recommended.

WARNING:Any prolonged or too intensive UVB exposure can damage you, your family, your pets and your plant, experience at your own risk.
WARNING: Any sane mind considers testing any new technique on a smaller population before applying it to whole your crop.


Member of the Month: May 2009, Oct 2010, Sept 2017
I'd never bother with black lights for UV-B supplementation - I'd just go to the local pet store (et cetera) and buy one of the various UV bulbs used to keep (many) reptiles happy and healthy. However, some of these lights also produce a certain range of UV-A wavelength (as, unlike humans they can see light in the 320-400 nm range, and the presence of such light promotes proper foraging, feeding, digestion, activity levels, social behavior, reproduction, and basking).

I do agree that "a little dab will do you"(r plants), lol. And it is not a bad idea to place a note on the door to remind you to turn off the ultraviolet bulb before entering.


Well-Known Member
Does anyone know if a black light spectrum causes any reaction (photosynthesis)? I’ll do more research tomorrow.

Old thread, but the wife and I were pondering. I’m curious to know what would happen if you replaced “dark” with black lights on.

Would it just look cool, or trigger something crazy?



New Member
Simulate moonlight? The only reason that the moon doesn't screw up the flowering cycle is that it doesn't reflect enough of the sun's light to be noticed.

The plants would do perfectly fine without any moonlight whatsoever.

I'll leave the tide-affects discussion to a plant biologist lol, but you know what I mean.

The only reason I can think of to have any light at all during the dark cycle would be if you are forced to work in your garden at that time. And in that event, you would want something in the green spectrum that the plants wouldn't notice (but don't ask me to recommend any particular type, I do not know exactly what range of "green" the plants don't use and it would be a real bummer to be off by just enough to cause problems).
one more thing for moon light, (I dabbled in Photography), The Light from the moon is Reflected Light, not direct light like the sun.


New Member
No, plants do not need UV light. It actually causes them harm. But in causing harm, it forces plants to protect themselves, which can result in a positive for our needs. Cannabis is the best example. UV light forces it to create more resin to protect itself, which means higher THC and CBD levels. For that reason, many marijuana growers look to add UV light to the final few weeks of the grow, when it has the most effect on the final product. But what is the best way to give your plants ultraviolet light?
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