Is there optimal amount of light that you can give for photoperiod plants? 18/6 to 24 hours? And when to swap?

[Delps8]

I just learned about DLI recently. You said you use that with the autos. I am curious now. So if one had enough ppfd, h2o and co2. Would one be able to light the room up for less that 12 maybe even 10hrs? For the record I am not an auto grower. Just seeking info.

"For the record I am not an auto grower. Just seeking info." - understood.

In theory, yes. Bugbee made a statement a la "We've never been able to give cannabis too much light". Below is one of the graphics from a paper done by Chandra et al at U Miss.



Each curve represents the change in net photosynthesis vs increasing PPFD for a given temperature. To get to 50 mols in 10 hours, you'd need to provide 1388 µmols (50/10/0.0036) and that falls well within the capabilities of cannabis to use that amount of light. I don't know the impact of 10/14 though on a photo in terms of being in flower.

The trigger to start flowering can vary between strains and, IIRC, the longest night time period to induce flowering in 13 hours. I'm not aware of any issue of night time being less than 12 hours. Have you run across anything about that?


This graphic is from the company that sells Photone, the mobile phone app to measure PAR. It doesn't deal with your question, apologies, but think it's a good graphic to have in this thread. This pertains to photos.

 

[Star Dog]

I’ve been running 12/12 from seed since March.

How are you getting on with straight to 12-12?

I've been thinking about trying seed to 12-12 for pheno hunting as yeild isn't really a factor just a tester would be enough and then clone/re veg if required.

I've never seen anything started with 12-12 I wouldn't mind seeing some photos early or/and late if you have any handy?

 

[hillbill]

I don’t do photos but 12/12 will bring single colas and I did my latest in Folgers 315 cup containers. Under a gallon and keep ‘em together. Taking fair amount of buds this way. Fun and variety.

 

[xtsho]

How are you getting on with straight to 12-12?

I've been thinking about trying seed to 12-12 for pheno hunting as yeild isn't really a factor just a tester would be enough and then clone/re veg if required.

I've never seen anything started with 12-12 I wouldn't mind seeing some photos early or/and late if you have any handy?

Here's a 12/12 from seed plant right after chopping/trimming. Harvested a little early due to circumstances at the time. Ended up weighing a little more than an ounce once it was dried. With the size of container "1.75 liter" I could fit 64 in a 4x4 tent. I've never done it but I'm convinced that with the right strain and 12/12 from seed I could pull 64 zips out of my 4x4 with a 600 watt HPS. But 64 plants is well above the 4 plant limit here so I've never done it. This plant was in the corner of the tent and not in the optimum light spread.

If I ever did decide to say screw it and ignore the plant limit I'd probably break out the 1000 watt HPS and go to town.

 

[GroBud]

All personal preference

Personally start under 24/0
Veg under 18/6
When plants cover tent wall to wall flip
12/12

I've ran grows at different light cycles that's what I've came to the conclusion for. But I've also ran grows outdoors winter time wasnt that much of a difference vs longer days. Plants can only consume so much light in one day regardless of how much light is provided. They'll droop towards end of light cycle that tells me I cant consume any more light. Why I stopped 24/0 also didn't see growth improvements maybe even slower growth. All personal opinion with current equipment and set up. Lights vary and need to be used accordingly

 

[Star Dog]

That's ideal @xtsho very nice, 64 of them would be great crop right enough, I'm going to give it a try and see how goes, thanks for posting the pics that's appreciated.

 

[madvillian420]

The amount of folks wandering into growing and immediately pondering reinventing the wheel always made me chuckle. Why are there so many of these threads lol?

 

[xtsho]

That's ideal @xtsho very nice, 64 of them would be great crop right enough, I'm going to give it a try and see how goes, thanks for posting the pics that's appreciated.

I'd really like to see the results if you do.

There are two key things that I've identified to make it successful. One is growing the right strain. You want something that will grow one bud without a bunch of branching. An indica like PCK would be good but there are more potent indica and some hybrid strains that would work. Some sativa dominant strains might work. One that comes to mind is Chocolope.

The second issue I've identified growing that many plants in a small area is irrigation. That's much too many to be hand watering and any drip system would turn into a nasty mess of lines and drippers. Because of that I'd go with coco as a substrate in square black nursery pots on a capillary mat.

 

[xtsho]

The amount of folks wandering into growing and immediately pondering reinventing the wheel always made me chuckle. Why are there so many of these threads lol?

Nobody uses the search function to see if one already exists?

That's all I can think of.

 

[twentyeight.threefive]

Almost all experienced growers will have some dark period in veg. Think outdoors...is anybody growing in 24 hrs of strong lighting?

This is a terrible analogy, and a dark period isn’t required. Comparing limited outdoor lighting with unlimited indoor lighting isn’t even close to the same.

The end answer comes down to DLI.

 

[Blossom21]

Well then do your own study on your next grow and share your findings. Make sure you document everything especially the methodology used.

I'd do that if i had multiple identical growing spaces with similar settings. Studying would take a lot of time and i don't have time or resources to study how plants grow unfortunately.

The amount of folks wandering into growing and immediately pondering reinventing the wheel always made me chuckle. Why are there so many of these threads lol?

Nobody uses the search function to see if one already exists?

That's all I can think of.

I apologize for not being a pro using the search function even tho i've tried, for real i've tried searching about this topic, but couldn't find any real studies or people done this themselves with identical setups like a "real study", that would answer my question about photoperiod plants growing under different lighting (including other conditions) conditions that would give me peace about this topic.

Maybe i've used wrong search terms or something. But i've read a lot about pretty much about everything else related to plants from different sources and can grow good cannabis with the "normal" cycles, but lights overall are a little bit a grey are to me. Sure i've seen people to grow their plants from the start with 12/12 to 24h or so (more light with autos), but i personally would like to get a source for photoperiod sources done with professional settings.

Those may be secretive or i just couldn't find proper sources, so maybe here's pro's who can guide me proper sources.

- I'm sure professional cannabis growers have done testing with their massive equipments and space how much root mass and stem growth resulting under different lighting conditions will produce for their own gain. Well "we" know pretty much most things already about growing, but i don't think most advanced growers don't even know "perfect" conditions. People mention everyone using their own preference, but if i got my hands to some (=all) of those real test results i'd die happy Home growers doing their little experiments are always different, and lack a lot of data so that's hard to analyze.

If you could guide me to right area or sources, i would be ever thankful. Maybe there's no perfect source for me, but at least i'm learning more.

 

[calvin.m16]

PAR Levels (PPFD)


Seedling / Clone: 100 – 300


Vegetative: 250 – 600


Bloom / Flowering: 500 – 1050

 

[Blossom21]

PAR Levels (PPFD)


Seedling / Clone: 100 – 300


Vegetative: 250 – 600


Bloom / Flowering: 500 – 1050

Is there any actual data supporting this? I always see different PAR suggestions eveywhere so a study with cannabis plants would make me believe you

 

[twentyeight.threefive]

Is there any actual data supporting this? I always see different PAR suggestions eveywhere so a study with cannabis plants would make me believe you

Just tag @Kassiopeija I’m sure she has a study saved somewhere on it.

The optimal amount of lighting will be dependent on other factors as well. Increase lighting and you’ll increase the demand for nutrients and CO2. If you can’t provide the latter you max lighting will be different then if you could increase the other factors. There’s no single number.

 

[Kassiopeija]

I'm on the mindset a dark period is beneficial, I had strange occurrences under 24/0 that went quickly away after giving them a dark period.

They also start smelling after approx. 1h in the dark more than if kept in light

Some physiological processes run higher at night

But if the DLI isnt met less light won't be helpful
But if light is too harsh, longer of it will cause problems getting further exacerbated

So main focus is DLI
that takes PPFD into equation, and that PPF over footprint
Depending on the state of the hardware just pick what works best

 

[ComfortCreator]

Is there any actual data supporting this? I always see different PAR suggestions eveywhere so a study with cannabis plants would make me believe you

Of course there is, and there are studies for everything else too. What doesn't exist is a perfect guide that guarantees you a perfect result.

And no study integrates every facet. That is why you go to experience...people have done this long enough to tell you what works.

Just like I can say nature informs us how to grow indoors. 2835 may think we grow in some space lab but it is an attempt to recreate outdoor growing conditions that WORKS.

Can you grow 24/0? Sure. But another simple analogy is like this - PEOPLE could live in 24/0, or 0/24. But we dont want to. Nature doesnt have a single place on earth with 24/0 or 0/24.

Nature is what we are working with, even if we are recreating it indoors.

Fluence's lighting guide is the closest thing to what you want, OP. Check out their pdf

 

[Delps8]

Is there any actual data supporting this? I always see different PAR suggestions eveywhere so a study with cannabis plants would make me believe you

Yes. Tons of data, including pretty much every grow that's ever been done. data" ≠ reproducible research.

The ranges are so wide that you could drive a truck through them so that fact that they're "correct" is no great achievement. What's not included is the light schedule so you're only seeing ½ of the DLI equation.

In my non-CO environment, I use 24/0 for seedlings and 18/6 to 20/4 in veg and flower (autos). Seedlings get 25 mols and my goal is to get 45± mols in veg and flower.

For photos, I'd go with 24/0 for seedlings to get them to 25 mols as quickly as possible. Veg is 18/6 using as much PPFD as needed to get to 45 mols. Flower would be as much PPFD as they could handle in flower using 12/12. The upper limit for cannabis (the "light saturation point") in a non-CO2 environment is about 800 µmols. I've only been able to find that in one place and it wasn't a research paper. Bugbee doesn't talk much about non-CO2 environments, unfortunately, but he does pay homage to that figure in a couple of his videos. DeBacco University, also on youtube, recommends up to 900 and I think he cites Bugbee and Chandra (Google "Chandra cannabis").

If anyone has a better source for that value, or for the light compensation point, I'd appreciate a link.

In short, yes - there's tons of proof being consumed every day and there's a lot of research that validates those PPFD ranges.

 

[twentyeight.threefive]

I'm on the mindset a dark period is beneficial, I had strange occurrences under 24/0 that went quickly away after giving them a dark period.

They also start smelling after approx. 1h in the dark more than if kept in light

Some physiological processes run higher at night

But if the DLI isnt met less light won't be helpful
But if light is too harsh, longer of it will cause problems getting further exacerbated

So main focus is DLI
that takes PPFD into equation, and that PPF over footprint
Depending on the state of the hardware just pick what works best

You had issues under 24/0 lighting so you came to the conclusion that a dark period is beneficial. What a ridiculous logical jump there. I expect more from someone so scientific.

 

[Kassiopeija]

You had issues under 24/0 lighting so you came to the conclusion that a dark period is beneficial. What a ridiculous logical jump there. I expect more from someone so scientific.

there aren't studies for any details
some things are also obvious by association based on the standard textbooks on plant physiology
like chloroplast repair etc
the fact you are still ??? about that just reveils your lack of knowledge

 

[Kassiopeija]

oh I remember now why I had you on ignore my little friend
tags someone just to reply with offensive language
/ignore