Lighting requirement of the cannabis plant.

[Beta Test Team]

FAR-RED:

In terms of not adding extra far-red I was referring to white light. If you have a LED array, you need to add far-red if it's not already provided by the LEDs.

Read up on "phytochrome photoequilibrium," "phytochrome," "photoperiodism," "red far-red ratio," "shade avoidance reaction," and "Emerson effect" to get a better understanding about use of far-red light by plants.

We want a red:far-red ratio of around 1 to less than 4 for indoor lighting. Sunlight is 1.05 to about 1.2 in the day, and about 0.6 to 0.8 at sunrise and sunset.

For PPE (aka PPS, "phytochrome photoequilibrium") we want about 0.8 to 0.9, sunlight is about 0.5 to 0.72, except at sunrise and sunset when it's much lower.

UV-B:

What do you mean by "estimated range for UV-B exposure"?

Yes, UV-B should be applied through the entire life cycle. And yes, the same irradiance is fine for vegetative and flowering stages.

Once we carry out our planned research on UV-B and Cannabis we would have more and better info to share.

 

[Beta Test Team]

I don't know where would be best for this, but maybe here is okay?

This is for Ranger, and others, that may not have yet read this. This is about Cannabis in terms of cannabinoid production from blue, green, and red ranges, etc.

The study is old and by today's standards not well designed (if I recall correctly). It's been a long time since I've read this (many years), but I think I recall I thought it was flawed so of limited value. Though, it's been so many years maybe I'm misremembering.

Anyway, here you are. This version is free, otherwise it's not. I found this on Google as my local copy is corrupted.

Effect of Light Quality on Cannabinoid Content of Cannabis sativa L. (Cannabaceae)
https://docs.google.com/file/d/0B6bxf2wAXs2FWC1nRDk0cmZTQnV2Q1k5TUJkdjdKUQ/edit?pli=1

 

[Medicgray]

I tend to shoot for a proton flux of 1100 at the canopy, gives me roughly 900 at the undergrowth. You don't need 1000 watters for penetration, just a proper light setup to achieve the right proton density. I think if more people understood how to achieve the right amount of light w a uniform spread, more growers would get g/watt yields. Spreadsheet/ program would be quite helpful. How's it coming? I'm adding Plasma and MH to my current setup to more closely mimick sunlight. Will no how it works in 9 weeks.

 

[Beta Test Team]

It's coming a bit slowly, we had to take a break from development for the last week or so to work on other things. But this weekend we're putting in hours so hope to have it ready by early next week

We will upload it to a new web site we're part of (not a forum), I'm just trying to get the OK from moderators or administrators to share the file URL here but they seem to very busy and haven't responded to my PMs.

This site doesn't allow uploading of Excel files, or any compressed files, so this site is no good for uploading our work. And besides, we want to keep the uploads under our control, not the control of this site.

 

[LowWater]

Let me try to dichotomize and simplify my question.

Assume for the sake of my question a CEA (controlled-environment agriculture) commercial greenhouse grow. Assume as well that we are growing a hybrid C. sativa, C. indica greenhouse crop that's augmented by LED grow-lights when needed.

Converting YPFD (yield photon flux density) or PPFD (photosynthetic photon flux density) as available to DLI (daily light integral), estimate for me these two parameters:

(1) optimal vegging net DLI, and
(2) optimal flowering net DLI.

 

[Beta Test Team]

(1) & (2) = 30 (min) to 55 (max). Ideal range in my opinion would be 40-50 to reduce power use while keeping photosynthetic rate and growth rate high (greater DLI past a certain point doesn't mean better growth or yield, just more power usage).

I don't see a reason for starkly different DLI in the two growth stages.

 

[Pendleton]

Beta, regarding plants taking some time upon lights on to reach "full-speed" with photosynthesis - going full bore with lights works, but perhaps a power-saving solution would be to kickstart the room with a small amount of watts and then go up to full-power thirty minutes later?

Let me try to dichotomize and simplify my question.

Assume for the sake of my question a CEA (controlled-environment agriculture) commercial greenhouse grow. Assume as well that we are growing a hybrid C. sativa, C. indica greenhouse crop that's augmented by LED grow-lights when needed.

Unless you're growing a hybrid including European hemp genetics, you're not growing a hybrid with C. sativa in it(This may be the case with South American plants). Both drug groups - narrow-leaf "sativa" and broad-leaf "indica" are genetically C. indica.

 

[HUGE]

Tag

 

[Beta Test Team]

Beta, regarding plants taking some time upon lights on to reach "full-speed" with photosynthesis - going full bore with lights works, but perhaps a power-saving solution would be to kickstart the room with a small amount of watts and then go up to full-power thirty minutes later?

Interesting point.

Looking at it that way, reducing power consumption, using lower irradiance in the first 30 to 60 minutes of the day would have benefit. However, without doing the math I wouldn't be sure if it's a worthwhile reduction (this would include cost per kWh, for example).

 

[Pendleton]

I might be overreading but it seems an evolutionary advantage to keep a plant from burning excess energy during dawn. The plant that cranks up slowly saves a bit of energy during the weaker lit hours.

 

[Beta Test Team]

I might be overreading but it seems an evolutionary advantage to keep a plant from burning excess energy during dawn. The plant that cranks up slowly saves a bit of energy during the weaker lit hours.

I do think you're over thinking it, but as far as I know there hasn't been research into this topic (for any species). And I don't think I understand what you're referring to about plant 'energy,' as a phenomenon (plant produce their 'energy' from radiation).

It won't do any harm, that's for sure. Whether it will help (in terms of plant use of radiation) I have strong doubts, but you never know...

 

[Pendleton]

I don't mean energy any difference from what I'd mean in terms of caloric use of a human. No mumbo jumbo here. Just that a plant opening its stomatas fully upon dawn light might not be as efficient over many generations as a plant which slowly picks up its daily processes over the course of 30 minutes as the sun comes up.

 

[shaggyballs]

Beta Test Team dropped some good knowledge here too!

 

[wassupmane]

i use these cheap luxmeters .. cheap but useful

i veg and flower under hps no more mh or neon .. and i speak of small cut full of roots in the 77 trays
i these conditions giving the right amout is crucial because i made the sour experiences several times to burn the tiny plants with too much light intensity ..
it lead to deficiencies and stress

now i can say i go from the beginning to the end under 600w with plants praying all the time

when i put them in the cubes i give them no more than 10 000lux on the meter ..
in veg plants have 1/3 more time of light so i find normal to give 1/3 less lumens ..(see DLI daily light integral, agricultural articles)
it makes around 100 with the x100 setting on the luxmeter
if i had a real haze cut ( what i try to find) i will do direct 12/12 and give around 15 000 lux .. with co2 maybe a tad more and its no even sure
when plants are put to root the need less light, like you do under the t5 to root your cuttings.. so i lower he hps only after a week and then i dont touch it for the rest of the grow .. one buds will grow and finish at 1.5inch of the bulb .. which makes around 50 000 lumens.

with this intensity of light and the right temps at the canopy the thc will literally explode at maximum

in veg i woudl give between 10 000 to 30 000 lux
and in flower from 20 000 to 50 or 60 000 on the end ..

 

[wassupmane]

GroWweedeasy gives pretty similar value as mine
Always found this site was pretty serious ..




Not sure the images will work first one at repoting day with around 120 lux on the tester.. and 12 days after of 18/6
Exodus cut is pretty slow vegg I found, but nothing surprising for a 30 year old plant

 

[TychoMonolyth]

I walked into a local grow shop (there are more now that it's legal) and was looking at his lights. I asked him "Where are your LEDs?" He said "We grow weed, not Basil." lol. I was stunned for a minute. Apart from his air of superiority pissing me off, he's missing out on a lot of sales. Not everyone lives in a big house with two trucks and plenty of cash for electricity.

I have to admit I don't have any experience growing indoor and just starting now. Was he right about basil? Are LEDs that bad? I've seen some pretty amazing pictures of LED grows on here.

 

[I wood]

I walked into a local grow shop (there are more now that it's legal) and was looking at his lights. I asked him "Where are your LEDs?" He said "We grow weed, not Basil." lol. I was stunned for a minute. Apart from his air of superiority pissing me off, he's missing out on a lot of sales. Not everyone lives in a big house with two trucks and plenty of cash for electricity.

I have to admit I don't have any experience growing indoor and just starting now. Was he right about basil? Are LEDs that bad? I've seen some pretty amazing pictures of LED grows on here.

I have not much experience with LEDs but they are worthy if used appropriately.
This summer heat, curiosity, and lower electricity had me replace a 400 watt metal halide with about 120 watts of screw in LEDs.
Growth was better and nodes spacing was tighter, overall better looking plants. Very eye opening experience. More LEDs will be in my future.

 

[ESTERCHASER]

Yes. But you don't want to provide over about 1,000 PPFD all day unless your environment is VERY controlled. We tend to use 700 to 800 PPFD all day for Cannabis (I didn't include our reasons, as I think I'm typing too much in each post.)


No. Far-red isn't something you would want to add to your spectrum normally, unless for very special use-cases (not photosynthesis). And UV-B should be applied all day, like PAR light. (UV-B can be over applied, just like PAR light).


Yes, please, ask what you are wondering. We may not be able to answer always, but when we can we will.

i think the spreadsheets are great but can you tell me what you use for bulbs and lighting?

 

[ESTERCHASER]

I walked into a local grow shop (there are more now that it's legal) and was looking at his lights. I asked him "Where are your LEDs?" He said "We grow weed, not Basil." lol. I was stunned for a minute. Apart from his air of superiority pissing me off, he's missing out on a lot of sales. Not everyone lives in a big house with two trucks and plenty of cash for electricity.

I have to admit I don't have any experience growing indoor and just starting now. Was he right about basil? Are LEDs that bad? I've seen some pretty amazing pictures of LED grows on here.

honestly.....i love screw in 100w feits screw ins for babies......i think until i can find a led i CAN HAVE TO TRY ill stay with hps 600 koooltubes and trying to grab as much sun as possible from windows and the rooftops

 

[bsgospel]

I walked into a local grow shop (there are more now that it's legal) and was looking at his lights. I asked him "Where are your LEDs?" He said "We grow weed, not Basil." lol. I was stunned for a minute. Apart from his air of superiority pissing me off, he's missing out on a lot of sales. Not everyone lives in a big house with two trucks and plenty of cash for electricity.

I have to admit I don't have any experience growing indoor and just starting now. Was he right about basil? Are LEDs that bad? I've seen some pretty amazing pictures of LED grows on here.

No, you're right. That guy is not watching where the puck is going, nor does he seem to have a good eye on it. He might be puck adjacent- someone just needs to show him what LEDs are doing now.