how to use U.V. lighting

UVA in itself won't do much but increase terpene/flavinoid profile if at all. Uva is in the range of 320-400, UVB 280-320nm UV studies have shown that there is a synergistic response between 285nm and 365nm. Uva is in the range of 320-400, UVB 280-320nm First one must understand UV RESISTANCE LOCUS 8 (UVR8) it is an ultraviolet-B (UVB) radiation photoreceptor that mediates light responses in plants. 95% of this response is activated at a peak of 280nm and nothing else. The dosage amount of UVB@280nm in order to activate the UVR8 photoreceptor is reduced if a 285nm peak is dosed with an equal 385nm peak. UV is measured and used by the plant to determine how thick a coating of trichomes will be deployed, given UVB is a measure of how much ultraviolet light from the sun penetrates the earth's atmosphere, which in turn determines how thick the sunscreen should be. But of course there is UV damage. Applying extra blue light to the plant can repair the damage done by most of the DNA damage, This is done using a process called photoreactivation, the plant harvests blue light to create photolyase enzymes that vastly multiply the plant's ability to repair DNA damage from UV light, hence allowing exposures exceeding all recommended dosing. UVB is only to be applied after half halfway point of day"light" schedule. UV + Blue brings out the anthocyanin in plants that hold a range of health benefits. UV has been shown to control over half of all the plant's hub networks for photomorphogenesis.

Adding UV-A lights to your autoflowering cannabis plants in a 2x2 space can potentially enhance certain aspects of plant growth. UV-A light is a part of the ultraviolet spectrum that falls between 320 and 400 nanometers. While UV-B and UV-C can be harmful to plants, UV-A is generally considered beneficial in controlled amounts. Here are some general guidelines on how to use UV-A lights: When to Start: You can introduce UV-A lights during the entire lifecycle of your autoflowering plants, from seed to harvest. However, it's often more common to use UV-A during the flowering stage, as this is when the potential benefits are most significant. Duration: Start with a short duration, around 30 minutes to 1 hour per day during the first week. Gradually increase the exposure to a maximum of 4-6 hours per day during the flowering stage. Distance: Place the UV-A lights at an appropriate distance from the plants to avoid causing stress or damage. A distance of 12-18 inches is a good starting point, but this may need adjustment based on the specific intensity of your UV-A lights. Frequency: You can use UV-A lights every day during the flowering stage. Monitor your plants for any signs of stress, and adjust the frequency accordingly. Observation: Pay close attention to how your plants respond to the UV-A light. Some plants may show increased resin production, enhanced potency, or improved terpene profiles. If you notice any negative effects, such as leaf burn or stunted growth, reduce the exposure. Harvest Timing: Some growers believe that using UV-A during the later stages of flowering can enhance the development of secondary metabolites, potentially leading to a more potent harvest. However, the impact can vary based on the specific strain. UV-A Light Source: Choose a UV-A light source designed for horticultural use. LED fixtures with a specific UV-A spectrum are common. Avoid using household UV lamps, as they may emit harmful UV-B or UV-C radiation. Always monitor your plants closely when introducing any new light source, including UV-A. Cannabis plants can be sensitive to changes in their environment, so it's essential to observe their response and adjust the conditions accordingly. If you're uncertain about specific recommendations for your particular setup or strain, consulting with experienced growers or the manufacturer of your UV-A lights can provide valuable insights.

Some LED fixtures haves UVA LEDs, but this kind of diodes are not very powerfull and can't harm your plants running all day (your plants should shield against it a bit anyway). UVB is another kind of stuff: because it's degrades DNA, it can give skin cancer to humans, and force the plants to make essential oil (Flavonoids and Terpenes) to protect against it (like we tan). But it's only available as fluorescent tubs (like the one from Migro) and you should use it around 2H in the middle of the "day", only during late flowering, with a sign outside your box for you to known when it's running and don't harm yourself. Dutch Passion talk about how UVB increase terpenes in this article: https://dutch-passion.com/en/blog/how-to-increase-terpene-levels-in-cannabis-plants-n1037

don't use uv in vege. it stimulates trichomes, which don't develope in vege to any degree that matters. uv does not improve growth. it is a stress the plant reacts to by supposedly producing more trichomes. Also, plants build up resistance to UV. This is why earlier studies using field crops did not show a statistically significant correlation with UV and increasing potency. never used it, but those are the cause/effect of what is going on. my fc4800 has some uv diodes, maybe? small potatoes.. you can never polish a turd (bad genetics). any improvment is likely small.

I use the entire cycle usually half power during veg full power in flower. UVA will not damage your plants when used correctly, I would assume if u move them close at max power there will be a point they will. Mine are mounted on my main light so no worries for me. UVB is a different story, that you have to be careful with and are used differently. I don't have experience with those yet.