Plant stressing – A brief overview

Plant stressing is a fairly new concept, and someone could probably write an entire book on the subject. I expect someone eventually will, but for now, let me share a little basic theory, as well as some of the practice.

I’ve been familiar with the idea of plant stressing with ultraviolet for about 5 or 6 years.  The first person to approach me with it was a cannabis grower from California, I honestly forget his name.  He grew legally, for medicinal use, and had heard about using UVB as a way to increase THC, or tetrahydrocannabinol, the psychoactive compound in cannabis that is responsible for getting you “high”, treating pain and inflammation, reducing nausea and increasing appetite in chemotherapy patience,  and has a number of other medical uses.

At first, it sounded like left field science until I did a little research on trichomes, then it started making sense.  Within a couple of years, many people were asking for UV lamps for a variety of plants, in particular, tomatoes and cannabis.  After some trial and error, we were able to dial in on the specific frequencies that get the best results, and of course, that formed the basis for our current lamps.

Most of the testing has been with plants that have trichomes, including of course tomatoes and marijuana but also peppers of different types, and even some non-trichome plants such as flowers, although at lower levels of ultraviolet and for different reasons.  The theory is pretty simple, that plants act similar to humans, and they protect themselves when exposed to the damaging rays of UVB.  The role of UVA is still not fully understood.

When a human is exposed to UVB, our skin reacts by producing melanin, which is a natural sunscreen.  UVA causes melanin to oxidize, which means to turn brown.  That is how people get a tan, and a tan protects you from damage from UV.

In some ways, plants (particularly those with trichomes) are similar: If you expose them to UVB, they will create a resin that acts as a sun block.  In the case of tomatoes, that sunblock is called flavonoids.  In the case of cannabis/marijuana, it is specifically THC which is a somewhat clear resin that is exuded from the trichomes on the flower and sugar leafs of the plant.  The art lies in causing just enough damage to the plant to get a reaction, but not enough that you damage its ability to produce flowers.  Typically, UV isn’t used until the plant begins flowering.

The same is true with tomatoes, you don’t really benefit from UV until the plant has already been pollinated and fruits begin to appear.  In all plants, it is during the fruiting or flowering phase that it benefits.  Before you ask, I am talking about tomatoes grown in a greenhouse, which my sources say are the majority of tomatoes grown in the US now.  The glass from the greenhouses filters out most of the UVA and all of the UVB.  The greenhouse is otherwise a perfect environment, since they never see a storm, supplemental lighting can change the length of the day or insure they never see a cloudy day.  Adding UV lights simply replaces what they would normally get if there were grown outdoors, and in the end, makes the tomatoes taste much more like outdoor grown tomatoes.

Anyway, that is the raw, basic theory behind plant stressing.  In the coming weeks and months, I will share more info and specifics.  If you are a university that wants to test some of these theories with UV lamps, you need to just call meat 800-600-8118 x126.  We have a few universities that are already using our lamps (including some big names I can’t mention) but in exchange for test results, we can subsidize the lamps, making it cheap or free to test.

Dennis Brown