Understanding Light Intensity to Drive Cannabis Production

Understanding Light Intensity to Drive Cannabis Production
Professor DeBacco
Giving the Plant More Light…
When you give a plant more light this can theoretically increase photosynthesis and result in more biomass.
However, no other factors can be limiting for this to occur
(Ex. Water, nutrients, air,…)
Increasing PPFD past 850-900 µmol/(m2sec) will require carbon dioxide enrichment to take advantage of this level of light.
Light Intensity by Strain…
All Cannabis can be treated as high light intensity tolerant since all have been bred outside for an extended period of time during the history of the plants domestication process.
Growers Typically Increase PPFD as Plant Ages
While some growers increase light intensity with age, if the plant requirements are kept optimum plants can be grown at a high consistent PPFD.
This can be a challenge with water especially when plants (and root systems) are small.
Net Photosynthesis and Transpiration While Increasing PPFD
Photosynthetic response of cannabis
Variations in net photosynthesis in C. sativa with varying photosynthetic photon flux densities (PPFD) and temperature conditions expressed in Celcius.
Light Intensity Maximum
With no Carbon dioxide enrichment the maximum PPFD that the plants can utilize is 900 µmol/(m2sec)
For plants to use light levels over this CO2 needs to be added to the growing environment.
PPFD Level Determined by [CO2]
Since CO2 concentration will be the limiting factor the level of CO2 in a grow space determines the maximum PPFD the plants can use.
*Assuming all other factors are not limiting.
(Ex. Water, nutrients,…)
Light Intensity At Both Extremes
While growers focus on the maximum light intensity to get the greatest yield for photoperiod dependent strains it is also important to consider the other end of the spectrum.
While it can be difficult to measure very low light levels (without special sensitive equipment) it is also important to consider how dark the dark period needs to be.
How Dark Should the Dark Period Be?
Many growers will ensure there is not a pin hole size of potential light entering the plants during their dark phase, this may be unnecessary.
Full moon light will not impact cannabis (light sensitive at night, just like poinsettias)
However, it may not take much more light exposure than a full moon to have the plants consider it to be “day”.
So just realize dark does not have to be 100% no light
Link to Lecture Slides: drive.google.com/file/d/1e9hr...
420 Magazine Source Content by Slide Title:
Growers Typically Increase PPFD as Plant Ages
www.420magazine.com/mobile-ga...
*Due to the description character limit the full work cited for "Understanding Light Intensity to Drive Cannabis Production" can be viewed at... drive.google.com/file/d/1bLpP...

[@devinrowley732]

Awesome I am so impressed with the amount of information. I’m just a longtime craft grower and I love that I am learning new things keep the videos coming you rock

[@DeBaccoUniversity]

Thanks for sharing and always glad to hear that people are learning new things based on the content here at DeBacco University!

[@ScreaminBaby]

I've always thought that strictly maintaining 0.00% light during dark phase was a little extreme... and not seen in nature. Nice to hear someone a lot smarter than me agree!

[@DeBaccoUniversity]

This is what the data supports and indoor growers often forget about outdoor plants exposure to moon light at night.

[@chefmatte84]

You are the "Bill Nye the Sciense Guy" of the Lord's Lettuce! Thank you for all you do!

[@DeBaccoUniversity]

Thanks for the high praise!

[@bigtrader7924]

Bill Nye is not a scientist at all. He is an actor

[@samwest2675]

This guy has made thing so mush easier. No rubbish just good info.

[@DeBaccoUniversity]

Glad to hear you feel that way, hopefully others do as well.

[@stevehillbilly5797]

Great video. A lot of concern by home growers about “pinholes” in their grow tents. I tell them that the pinhole is noticeable from the outside of the tent when the tent lights are on. However when the lights are off in the grow room or tent that you’d basically need a spot light so to speak or at a minimum a light directly shining at the pinhole in order for any light to come through and possible trigger the plant. Pretty much direct light, ambient light from a nondirect point should never cause anyone issues. Thanks for sharing and stay safe and healthy. Peace ✌🏻

[@DeBaccoUniversity]

Many indoor growers neglect the idea that cannabis grown outside is exposed the moon light and this does not impact the overall photoperiod of the plant.

[@donjohnson9063]

All you have to do when tent is empty zip yourself inside when the other lights are on to see just how n what light is penertrating the pin holes or vent holes.

[@nihilityjoey]

@@DeBaccoUniversity I'd also like to hear your views about growers claiming that light leakage caused their plant to turn herme. I've had some light leakages in my grows that would make some of these growers have a stress heart attack, and I've never had a plant turn herme because of light leakage. Is that even a thing?

[@stevehillbilly5797]

@RANDOM USER exactly. The “Bro science” from the 70’s to the 90’s is just opinion and not based on facts. If the genetics 🧬 of the cultivar being cultivated are strong and properly bred the plant will almost never hermie. Otherwise plants hermie due to shitty ass genetics 🧬 or shitty ass grower talent. Peace ✌🏻

[@brianmorris364]

Also, this would be easily remedied with a piece of duct tape lol

[@SouthAfricanCannabisExtraction]

I am always just so impressed with the rate at which you publish content!

[@DeBaccoUniversity]

The rate may not be continuing forever, so enjoy it while its here and absorb as much as you can;-)

[@markeaton2003]

Good video. The moonlight aspect for indoor growers is very helpful. Thank you.

[@DeBaccoUniversity]

This is why this channel focuses on both indoor and outdoor production, there are aspects of each that the other may not realize/make a connection to.

[@skepticalgenious]

Thank you for this information. It has helped me to understand how to increase the lights ppfd with a co2 add and many other things. I used the knowledge you taught and took a vegetative cannabis plant down to 40 days. The same breed a (photoperiod) last crop took 68 days. Basically a whole month faster.

[@DeBaccoUniversity]

Thanks for sharing and great to hear of the increased in plant efficiency that will improve your overall harvest for years to come!

[@joshcrocker4596]

Top tier info! Thanks for the work you put in

[@DeBaccoUniversity]

You are welcome there is a lot of research ahead of time to make the video content direct and hopefully useful for people.

[@jdjones4825]

@@DeBaccoUniversity thank you 👍

[@jimmiller2767]

This channel is great! Thanks

[@DeBaccoUniversity]

Your comment is great! Thanks for your support of the channel.

[@MrOrangeQueen]

Amazing content as always!

[@DeBaccoUniversity]

You are welcome happy to produce quality content.

[@Kurtie7]

Thank you very much. You are good......very good. I am subscribed. Please keep up the great vids....Thank you again..DeBacco University.

[@DeBaccoUniversity]

You are welcome, be sure to tell others of the channel and information. Encourage them to subscribe;-)

[@thompsongl]

Excellent information and presentation !

[@DeBaccoUniversity]

Excellent comment!

[@kwartelhendrickson6960]

So happy you touched on the moonlight some people SWEAR that it has to be 1000% dark but also forget about the stars and moon also I’ve seen first hand in my own grows years ago that a small amount can come through (obviously not a lot) back then it was said they’d turn herm if they saw any light at night. Thanks for this.

[@DeBaccoUniversity]

Always happy to share the actual plant perceptions on light.

[@ironindica7342]

Awesome vid love the content 👌

[@DeBaccoUniversity]

Thanks for the comment always great to know the time put into the videos is appreciated.

[@mustangunique3214]

Good video!

[@DeBaccoUniversity]

Good comment!

[@chadwickalexanderjr1758]

I love science driven data based cannabis growing!

[@DeBaccoUniversity]

That is all you will find on this channel;-)

[@louistebo]

thank you

[@DeBaccoUniversity]

You are welcome thanks for the subscription!

[@jeffngarden]

Every Time you post a video, I yell 🗣Debacco‼️. Everybody around look at me 🥴😂 Thanks Sir great info per usual

[@DeBaccoUniversity]

At the rate the videos are being posted that sounds like a lot of "looks";-)

[@jeffngarden]

@@DeBaccoUniversity This channel is higher education like a University or something 📚😎

[@brianmorris364]

I'm curious about uva and uvb lights effects on cannabis. Please do a video on this subject

[@DeBaccoUniversity]

This may help provide some helpful information... kzbin.info/www/bejne/q56QZHuQjauhmZY

[@manolimanioudakis8456]

Hey professor! Quick question here. Is all light equal, specifically how plants interact with light intensity? Might seem funny but I'll give an example to showcase my point if there is one even. Our light fixture is an HLG LED with an infinitely overclockable driver/extrusion (I think it's called that) that doesn't fluctuate temperature or humidity. We hang it from 5 different points with different power levels to achieve the same 1000 ppfd across all 5 points. 1billion%power hung at 9.41 million miles 150%power hung at 200 inches 100%power hung at 40 inches 60%power hung at 30 inches 10%power hung 1 inch.

[@DeBaccoUniversity]

These DeBacco University videos may also be helpful for you... kzbin.info/www/bejne/l6aaeGCli6mYgck and kzbin.info/www/bejne/qGjchZyLhNmGftE

[@manolimanioudakis8456]

@@DeBaccoUniversity appreciate the response professor.

[@bryanbest7525]

What is the minimum amount of supplemental light needed to prolong days for greenhouse grows? If I only get 12-13 hours of sun light what is the lowest ppfd range that would work to prolong the days without causing flowering?

[@DeBaccoUniversity]

Not much is needed, basically above a full moon clear night level.

[@bigtrader7924]

The sun has one small focal point. Par from LED has thousands of focal points. Measuring ppfd with a meter is inaccurate in turns of angles. For instance if you take an outside reading ppfd it will be lower then center. But if you angle that meter from the outside towards the center the ppfd goes up. This changes the idea of how much light you are actually getting. Your plant is getting light from many more angles at different levels of PPFD compared tot he one focal point of the sun.

[@DeBaccoUniversity]

But the sun moves changing the angles and adds heat to help drive photosynthesis.

[@bigtrader7924]

@@DeBaccoUniversity Yes exactly the sun moves so the plant is not getting a constant at all angles versus led lighting that has 1000+ constant focal points. Saying the sun adds heat is like saying the sulfuric acid added heat making the water boil. No the Hyrdogen creates friction with the oxygen. The sun doesnt add heat the sun excites electrons on the earths surface. I hope you are not a professor

[@polandsgarden]

Should you lower light intensity in late flower to boost resin and trichome production?

[@DeBaccoUniversity]

Some argue increasing certain wavelengths (ex. UV) late in flower can increase production, others do a lights off period. Data is still pending to determine the "best" method, but remember either of these is to maximize production so it it more important what you do for the majority of the flowering cycle than just what is done in the last few days to get the majority of the quality you seek.

[@paulg3012]

Considering how fast light intensity decreases when the distance is increased (inverse square law) I always marvel at how far above the canopy some big grows seem to position lights, looks like 8 feet in some (GW Pharma for instance).

[@DeBaccoUniversity]

Also, consider just how far the sun is away from the Earth.................

[@Trippopolis23]

my question about the light at night is that the sun is not giving the plants direct waves of lights from the sun they are reflected off the moon and then enters our atmosphere. Do you think that because of this reflection there are enough photons lost to not affect the plants outside and when we grow in doors if light is to get through that would be direct light with im guessing more photons to disrupt the cycle of the plant?

[@DeBaccoUniversity]

Reflected sun light in the form of moon light is not intense enough to be perceived by the plants.

[@andrewbee82]

Thx for the infos!! Can I ask a couple of q? First you say that we need co2 supplement over 1000ppfd than the graph says that normal ambient co2 4-500ppm limits the max light usage to 500 ppfd...so with normal co2 is there any benefits to give let’s say 800ppfd? Second question is about the average ppfd. How should the measurements have to be taken? Let’s take one plant covered by one single grow light. The plant has i.e. 5 colas at different heights (apex 1000ppfd, 2 at 800ppfd and 2 at 500ppfd). Should we consider an average ppfd (720ppfd in this example) or just the ppfd on the main cola? Same doubt about ppfd measurements taken horizontally if you have an even canopy. Hope you will explain. Thank you

[@DeBaccoUniversity]

Normal CO2 target light levels should be in the 800-1000PPFD range (keep in mind that seedlings/clones may need to be started lower and then worked up to this level. Take a set plane/distance from the light and measure the PPFD in the coverage area via a grid points. This is what is commonly seen with light data reports.

[@andrewbee82]

@@DeBaccoUniversity thanks so much. And what about different heights (not trained plant)? Any case the point is that ppfd coverage must be an average not just the hot spot, right? 800-1000ppfd for auto flowers too? Also with 18/20 daily light hours?

[@Trrenik0kb]

@@andrewbee82 keep it simple bro. You don't need to go in to science that much. Follow the light instructions for height and intensity and you will get to harvest without problems. 😉 If you put more than 1000 ppfd introduce co2 and that is it.

[@thresh0014]

It won't even pay for your Co2 so it's not really needed to stay at such high levels and if temperatures are below 90 then co2 won't matter anyways. When one area increases all areas (water,soil,wind etc) have to be increased as well so if you run at those levels it's going to be a chore to even keep them watered in anything less than a 10 gallon pot and they're going to take ferts like a you've never seen. Hard to maintain a all round very high PPFD without have a very dialed in room and grower that's on his toes. I don't think all the extra cost and trouble have been shown to be worth the effort but things change all the time

[@ClearWater7.62]

Hi, I have plants in my green house and will be bringing them in soon to flower under led lights. I'm confused and not sure what to set the light intensity at.. i have a controller that can set it 0% 10% - 100%.

[@DeBaccoUniversity]

Test the PAR rating and then use this video... kzbin.info/www/bejne/l6aaeGCli6mYgck

[@phantom-boogie]

What could be proper EC for a 300w, 700~ppfd setting? Indoor soil.

[@DeBaccoUniversity]

General suggestion is 1.8 in Veg and 2.4 in flower.

[@phantom-boogie]

@@DeBaccoUniversity really? I've been experiencing burnout in the leaves, week for onwards. Dinafem Moby Dick (former dane bank), with Green House Feeding salts (the dutch ones, grow+long+pk boost), averaging 1.5 across, and 1.8 in the final weeks. I felt that my ppfd was low, and i was overfeeding thus the burning. Maybe flushes were lacking? I just recently started flushing at the beginning of flowering, midterm, and preharvest.

[@brianmorris364]

Viewing plants under a weak green light will not trigger any responses in them. Green light works well for viewing during lights out periods.

[@DeBaccoUniversity]

Have you seen this DeBacco University video... kzbin.info/www/bejne/gGTRgqmFhbCEkNk

[@akilletaylor6628]

Hey goodday Can you do a video comparing colloidal sliver and sliver thiosulfate?

[@DeBaccoUniversity]

At this time this is not being planned for.

[@akilletaylor6628]

@@DeBaccoUniversity but are there any significant differences between these two and where can I get material on this topic

[@DeBaccoUniversity]

Maybe this video can help you... kzbin.info/www/bejne/nKqtZ6unnpymppY

[@SlamFM36]

I've wondered what the plants perceive as "darkness" compared to humans. My outdoor photos start flowering well before it gets down to 12 hours of darkness.

[@DeBaccoUniversity]

"light" as seen by plants is very dim when it comes to determining photo-period. Some have suggested levels slightly above a full moon.

[@BangBangBang.]

Thank you about the moon. I had a debate with a guy who couldn't really answer my question "what about a really intense full moon" about his concerns with lights because he was under the assumption you had to keep it completely dark sealed during the dark period. I told him I had to get back there to do some quick maintenance with a really low power flashlight. The easiest way if you need some stealth or foolproofing, take the light bulb out of the ceiling socket if you're a home grower. Use headlamps.

[@DeBaccoUniversity]

You can also use a green light (headlamp or bulb) which can help maintain the photoperiod of the plant as well.

[@dr.trichome6419]

Autoflower is a bit more sensitive. Definitely be careful. Great video

[@DeBaccoUniversity]

As with any variety, make changes slowly and in moderation and then determine results and make modifications based on this information.

[@dr.trichome6419]

@@DeBaccoUniversity indeed i change percentages on the dimmers mark it down and examine the results than adjust as needed i found my sweet spot or their's they're growing rapidly. Thx for the videos.

[@muthrfuqrjonz3530]

Autos? Why would anyone want an Auto?? Photo period only IMO. The list of reasons is a long list.

[@johndonlevyjr8776]

Great video! I just went into LED 180w. With dimmer. Woke this morning most leaves curled. I moved up the light 2.5 ft. above the plant. Should I dim? My plants are in 4th week. Using ebb and flow. PPM 680. PH 5.9 6.12

[@dr.trichome6419]

@@muthrfuqrjonz3530 because im not going to be married to a photo for 8 months and i actually know what im doing ill have 4 harvests this year i get to see results of mixing strains i can think of a 1000 reasons why i won't grow photos autoflower nation baby 🔬👨‍🔬🤙👌

[@dianah6937]

Thanks for the effort that goes into these videos. Could you talk a little slower. The material isn't easy and a lot of the terms are new to me. Maybe it's just me, and if so, ignore with my blessings.😀

[@DeBaccoUniversity]

You can always slow the delivery down (or speed it up) via the playback speed;-)

[@hunggar4659]

Just a question about moonlight, if it's not 12hours + of moonlight isn't the argument moot?

[@DeBaccoUniversity]

Not necessarily, since the plants need 12 hours (or more) of continuous darkness. Moonlight was thought by some to break or interrupt this continuous hours of darkness leading to the issue of preventing flowering even though there is not enough light intensity from moonlight for the plants to perceive it as light.

[@hunggar4659]

@@DeBaccoUniversity right, but there has never been 12 hours of moonlight, it doesn't wane like the sun during seasonal changes. All cannabis have grown in fields and mountain sides throughout time, you'd figure the argument would be dead and done. Also the moon is reflected light so it's composition would be different and maybe any light wave the plant would recognize as a hormone 'trigger' might not even be there at all... Just saying commenting on 'myths' without a proper 110% explanation just continues the cycle of misinformation. 'Belief' statements should never be used in science. Great videos but I would spellcheck your power points, makes you look bad...really bad.

[@anthonyromano8565]

The graf that shows plants not being able to utilize more than 500 PPFD can not be talking about cannabis. While most growers will be at 600 to 700.

[@DeBaccoUniversity]

Assuming this is the graph that first appears at 4:34 this shows that CO2 can be limiting and at lower leaves adding more light is generally not fully utilized by the plant. Aiming for 600-700 ensures room for error and if you are supplementing with CO2 you can go over 1000 to maximize the photosynthetic process. Hope this helps.

[@dano9411]

Algorithm

[@DeBaccoUniversity]

Thanks for the help!

[@iainbambury1888]

I want to start not GT money by lights the deer I'm from Scotland want a Lux I'm from. Scotland can you help a brother out looking for cheep full grow tent starter pack sir want do deep water culture system please gt bk to me

[@DeBaccoUniversity]

Many retailers have starter kits that you can use as a base. Here is a quick look at a ventilation system for a grow tent that goes through the ventilation related products step by step... kzbin.info/www/bejne/mJzUZmaHod95o80

[@thresh0014]

Cheap? Good luck, even middle of the road equipment you're looking at 1200+ for soil build(factor in fans,extension cords, surge protector, timers, pots, ferts and supplements etc... it's a never ending list haha) and god knows what for a DWC system.... Pays for itself first harvest tho. Go research and read, compare info on brands and learn the systems at which they're advertising, Do not buy a kit, I built one that was 8 times better than all the kits I've seen for less money. Stay away from blurpie lights. If you've never farmed before DMC is jumping into the deep end, one mess up and you've got a dead crop, soil is much more forgiving and your bud will taste better to :D

[@iainbambury1888]

Cool got hole ser up all good