Adding UV To A Grow

[bluter]

I'm not sure wether we're looking for clinical differences here? I wouldn't expect much difference in trichome production like more or less or larger or smaller but maybe more what's going with the terpenes & ratios.

uv is a stressor like any other. the plant will react to it to some degree in trichome production, the same result as other stressors.

overexposure actually degrades trichomes, and the plant may exhibit light avoidance and other light damage issues. it's a fine line balance.

As I find the same strain accents very different flavours if it's grown under the Sun, HPS or LED.

the quality and type of light will always have an effect. climate and soil conditions will change things greatly. in winemaking it's part of the terroir, and it's quite important.

the terpene wheel, is a direct development from the wine flavour wheel.

 

[stinker]

overexposure actually degrades trichomes, and the plant may exhibit light avoidance and other light damage issues. it's a fine line balance.

Thanks bluter. I've chatted with someone else online that's using these same UV fixtures. He says he runs them full time in flower on a large scale. Says they are mild but really do increase the terps. I'm not sure they are worth the effort yet. I did put 3 un-sprouted germed beans in soil inside the tent. They all popped fast & had 2 hours of UV included with their 1st night above ground. 1 reached up big time. Took them out today , they wont go back in. I don't want to take the chance of damaging and these need to acclimate. Will bring in at night until it warms up some more. Its 21c today.

As I find the same strain accents very different flavours if it's grown under the Sun, HPS or LED.

I've never used HPS and am fairly new to LED. I do love the sun. This summer I will grow two outside that were grown inside. Will also be taking a summer break inside. Well grown outdoor bud is the best!
---------------

There are mixed opinions on what to expect when using UVA and UVB. Is it worth it? There might also be other benefits like deterring mold and pests. Its hard to say before the grow has even completed.

When I start indoor again in the fall I'll be in a larger taller tent. I'll also be trying another light fixture with a high number of Hyper Red diodes included in the spectrum. Its a usable red (660 nm) that will run whenever the bars are on.

 

[Fenderbender]

What is reaching plants that are fed by the Sun? This will probably be very different depending region, weather & time of day & year as many factors determine how much reaches the ground.
But let's say in the good and well known cannabis regions during flowering.
Anybody know?

And what reaches plants with these added fixtures?

 

[TorturedSoul]

Well grown outdoor bud is the best!

That's debatable. I've never heard of caterpillars sh!tting in bud that was grown indoors.

There might also be other benefits like deterring mold and pests. Its hard to say before the grow has even completed.

My guess is that the amount of UV radiation that is produced by the average supplementary indoor garden product won't have much of an antifungal or antimicrobial effect. Again, that's merely a guess. But the "anti" UV devices I've seen concentrate their output into a very small volume - a handheld sanitizer meant to be practically in contact with the surface the person uses it on, an addon to a ventilation duct run, or the type that works on water that passes through the device. The gardener can run UV lighting for longer periods of time, but it's still going to be in a relatively large volume of space.

I would love to learn that I am completely wrong, and that it will help with the things you mentioned.

 

[TorturedSoul]

What is reaching plants that are fed by the Sun? This will probably be very different depending region, weather & time of day & year as many factors determine how much reaches the ground.
But let's say in the good and well known cannabis regions during flowering.
Anybody know?

It can vary wildly depending on altitude, latitude, etc. This (archived) web page has some "average" numbers and general information, if I grabbed the right link:

Introduction to Solar Radiation

And here is a scientific paper. It's titled "UV measurements in the 3000–5000 m altitude region in Tibet," but also mentions Mauna Loa, Hawaii and San Diego, California:

https://agupubs.onlinelibrary.wiley.com/doi/full/10.1029/2006JD007700

For cannabis I'm thinking we want at least 4% of the total output to be UV, with an upper limit in the 6% to 7% range. But I don't remember the calculations I did to come up with the "upper limit" numbers,, and could have botched the job, lol. I was trying to estimate the... whatchamacallit. the maximum sustained amount that cannabis growing at the highest altitudes might receive, not how much a plant could tolerate in small doses.

 

[stinker]

Eventually I ended up increasing the UV light hours to 4 hours per 12 hr, lights on cycle. I'm not able to say if using the UV bars were a benefit. I don't see any real difference. They might have contributed to some fan leaf crisping. If I use again it will be for the full 12 hours/lights on in the future.

 

[Fenderbender]

Nice buds!!! yeah I don't think that's going to be a very wild visual difference adding a bit UV.
But the terpene content and ratios might be different than grown without.
I also don't think you want it on full 12 hours as during the day there's a curve to UV outside.

 

[Madddogg]

I like the idea/think there is some science to this, but admit to little relevant field testing. I did run two LUCKY HERP UVA UVB Reptile Light 10.0, Desert UVB 150 Compact Fluorescent Lamp 23W UVB on my prior grow (Grandaddy Purple) the last 3 weeks of flower. I worked up to 2 hours per day, in midday like you were doing and she was marvelous, but I'm not sure there is a correlation. I was unable to run them on my last grow but can't say I noticed a difference. I'd like to run a side by side compare with the same strain, one with and one w/o UVB, but I just dont have the room.. What UV puck do you use?

I understand that reptile lights are for reptiles and are not powerful enough to affect cannabis. After reading various sources I opted for California Lights UVB fluorescent fixture, more expensive but designed to be used for cannabis during the last couple of weeks of flowering.
Will let you know the results soon

 

[gr865]

I understand that reptile lights are for reptiles and are not powerful enough to affect cannabis. After reading various sources I opted for California Lights UVB fluorescent fixture, more expensive but designed to be used for cannabis during the last couple of weeks of flowering.
Will let you know the results soon

I jabber there same unit.

 

[gr865]

I jabber there same unit.

No proof reading on this end.
That should be I have the same unit! LOL

 

[Delps8]

I'm not sure wether we're looking for clinical differences here?

Anecdotes ≠ data.

If someone is doing a controlled grow (biggest issue is to use clones), provides the data, and documents their method in significant detail, such that the results can be reproduced, and then the expirement is reproduced getting the same outcome, that's convincing.

Lacking any of those items, it's a grow journal.

Harsh? Not really.

To my way of thinking, it's better to have something that's proven to work than it is to have growers spending $$ hoping to get a tiny improvement in quality but they end up having pissed away their time and money.

My push - spend $32 on a lux meter (Unit-T Bluetooth) and feed your plants well by getting your PPFD to 800-1000k µmols. The biggest downside to that approach is figuring out what to do with all the weed.