Grow Tip: Boost THC With UV Light
2 min

Grow Tip: Boost THC With UV Light

2 min
Growing Seedshop
Want to boost the THC content of your bud? A UV lamp may be the answer.

For many, growing cannabis is about perusing a high THC content. As a cultivator becomes more experienced, they tend to pick up certain tips and tricks that help really push their green beauties to the limit. Well, here is a new one: add a UVB bulb to your grow.

That’s right, new findings from a group of cannabis researchers in Maryland suggests that by exposing cannabis to UVB radiation, cannabis plants produce up to 28% more THC! It is a theory that has floated around the cannabis community for a while, but is now scientifically proven!


UV radiation, also known as ultra violet radiation, is a natural part of sunlight, and is required in the production of vitamin D by most animals. UV light contains various spectrums. UVB, which is mentioned above, is just one of them. UV light also contains the UVC spectrum, which is known to be very damaging to life - so it is important to make sure you get the right kind if you are planning to try and boost your cannabis. Even overexposure to the less harmful UV spectrums can result in sun burn and damage.



To get the desired effect, a special light bulb is required that mimics the rays of the sun – often known as a sun lamp. In the research, a 40w fluorescent sunlamp was placed 25 cm above the canopy, along with some cellulose acetate to filter out the UVC. It is also possible to use the UVB emitting lamps available from most pet shops, but the smaller ones are probably going to be too weak, even for small grows.

If you are growing outdoors, then there is very little you can do to manipulate UV light. You will just have to be content knowing this little extra bit of knowledge. However, if you are flexible in location, or happen to live near a very big mountain, then there are some steps you can take. The intensity of UV light increases by 4-5% for every 300m ascended. So the higher up you grow, the stronger the UV is going to be. It is now theorised that this is why Moroccan hash, which is often grown high up in the Rif Mountains, is so potent. And don’t worry about UVC light in an outdoor situation, the O-zone is pretty good at filtering most of it out!

The findings of this research sheds a lot of light on a potentially whole new aspect of growing cannabis. We are very keen to see this theory put into practical use. So if you do try it out, let us know how it goes! Who knows, these findings could lead to a whole new generation of grow lights!

Note: The research found that only the THC content of the cannabis appeared to rise. Unfortunately other cannabinoids, like CBD, were not affected.

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