Black Light for Growing Weed

A lot of people recently have been asking me a really interesting question. They ask “can I use a black light for growing weed”? Well, I did a bit of research, and the information I found has actually been very interesting and eye opening. Hang in there, and maybe we can try out some cool new grow techniques to really kick your operation into the highest gear possible.

So why a black light for growing weed, what makes it so special? It produces special kinds of light, it’s called ultraviolet, or UV. You would have heard of this term before, as the sun creates a lot of UV, and plants use it to assist them in photosynthesis – the creation of plant food. Sounds pretty good right, well is it myth or reality then, using black light for growing weed? Read on to find out.

What is UV Light?

So, we all know that the sun creates massive amounts of ultraviolet radiation. As such, all plants – and organisms in general – are well equipped to deal with this kind of radiation. They all have certain responses to this. For example, humans sometimes blister over, get skin burns, and then the top layer peels off due to the damage.

How Does it Effect Weed?

Weed responds a little bit differently. Using a black light for growing weed engages the plant’s defensive mechanism, to protect itself. What is the plant’s protective mechanism you might ask, it’s not like it’s going to shed the outer layer of its skin. No, it uses natural resin production to coat it in a layer of THC which protects it from the UV.

Does it Actually Help Growth?

OK so now that I got you all excited, it’s time to rain on your parade. First of all, you can’t use a black light for growing weed explicitly. Remember when I made the post about lights? Well, weed needs a nice broad array of wavelengths to grow. It needs real visible light to actually create glucose and grow – it needs a LOT of real light to grow nice and dense.

So, putting your weed underneath solely UV lights will do basically nothing except for ravage its genetic makeup and starve it of actual visible light radiation. UV doesn’t tickle the weed’s photo-receptors like visible light does – it’s not the right frequency to engage the process of photosynthesis.

Is There any Use For Black Lights in a Grow?

For this reason, you must combine UV radiation with actual visible light to really make the plant respond in the best way possible. You might know that most LED panels nowadays do indeed include diodes which radiate UV light. This is a great way to diversify your light creation, and so it might be a good starting place to buy an LED panel which includes UV diodes.

Most of these diodes produce UV-A light, there is also UV-B. Unfortunately, sources of UV-B cost hundreds of dollars, and will definitely NOT give you a good return for your money. Fortunately, using black lights of growing weed is all the same – whether it’s the A or B version, the plant responds exactly the same. Therefore, you can use a simple black light with other sources of visible light to create additional stimulation for the plant.

Even if your panel already has UV diodes, it doesn’t hurt to try also throwing in a black light for growing weed. This will add a little bit of aggressive damage to your plant. Remember, we live in a world where organisms must adapt, and since they are not a stranger to UV, it will kick them into a defensive adaptation of covering themselves in thick, sticky, intoxicating resin! Isn’t that so dope?

Maximising the Results

So, the question remains, when is one supposed to use a black light for growing weed? Don’t use it during veg state, as this will do absolutely no good. All it will do is add heat, and excessive stress during the poor little plant’s youthful phase. This will definitely not do anything good for your harvest.

To get the most out of using a black light for growing weed, engage it in the last 2-3 weeks of flowering. This will kick the plant in the behind when it is already fully matured, and ready to make tons of resin. In the veg state, no resin is being produced at all, and so it won’t do anything beneficial.

Don’t waste your money on those super expensive UV-B bulbs – in fact, don’t even look then up unless you want to have a good giggle. A nice reptile light, or some kind of black light would be perfect for the last few weeks of growing weed.

Also, this is a rather advanced growing technique. It’s not something you would really just want to start off with. First, get down a few really nice rotations of dank kolas, and then once you do that, maybe add a few black lights for growing weed. This will most likely boost your yield – maybe not in weight, but perhaps in THC content.

Nice Black Light Options
Exo-Terra Reptile Light (UV-A & B)

This is a nice cost-effective solution to get started with using black light for growing weed. It’s supposedly got both A and B type radiation coming off the bulb, and doesn’t cost very much at all. 

OPPSK Black Light Bar (UV-A)

Pretty neat solution if you are interested in something like this. It’s 16 ft, so it can fit in any grow tent, and be turned on during the end of flower state to shower plants in UV.

Onforu LED Black Light Strip (UV-A)

This is a cool option for those who want to line the tent in UV radiating lights. This can be applied to the roof, or the sides of the tent to create an ambient UV radiation blanket.

Remember, the plant can NOT create glucose from UV radiation, and so it does not actually enhance the structure or weight of the plant. All it does is cause minor damage to the organic matter, and so to defend itself, the plant makes more resin, but not more structural material though, quite different.

If you want to increase the actual weight and density, you will either have to change the lighting or feeding regimen. These are the two most important factors to making fat kolas – and of course, keeping a nice stable environment within the operating boundaries.

For information on how to create a killer light setup, check out my Complete Lighting Guide for Grow Tents. In addition to the lights, you also need a perfect nutrient regimen, so consider looking at my Step By Step How to Feed Plants post to learn more about that.

Well, thanks a lot for sticking though this one guys. I think that this is a really cool advanced technique, and I was really surprised at what I found when considering if you can use a black light to grow weed. Short answer, no, but it does help with resin in the last few weeks of flowering. That’s the take away from this information I suppose, if anything. Have a good one, and happy growing.

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