DLI At Flowering - Photone's Guide

[MidgeSmith]

Hi,

 

I was thinking about the thread about turning down lighting in the last few weeks of flowering and then today, I flipped my growroom to flower after 6 weeks in veg.

 

I plan to follow Photone's DLI recommendations, but was shocked to see the suggestion of dropping the DLI so much, something that I haven't really done before while reducing the hours down to 12. 

 

So my question is, do you keep the light intensity the same (or even dim very slightly) when you go into flower and progressively build up the light intensity until bud growth is over, then dim the lights for the last 2 or 3 weeks as those buds finish of maturing?  Or do you just keep the lights as strong as you can, without burning, right until the end.

 

Has anyone done a side by side comparison with clones to see how these two different approaches compare?

 

The Photone DLI chart that I use is below :
 

 

Edited November 17, 2023 by MidgeSmith

[MindSoup]

Photone? Is that the app that tells you to put a piece of paper over your phones light sensor? Not sure I'd listen much to them to be honest. 

 

Just like most other things with growing there's no set answer. How much light you should/can give depends on a multitude of factors, it's all part of the relationship between different environmental parameters. for Instance if it's very warm and very humid and high in co2 you can/should give a lot more light than if it's cold, dry and low in co2 etc

 

This guy will tell you everything you could ever need to know about lighting . Have a look for his other video's and interviews etc, he's a proper actual botanist that works for NASA and such and has been growing cannabis indoors since the 70s or something like that, pretty much the world's leading expert on indoor cultivation. 

 

 

 

 

[handysmoker]

Hey @MidgeSmith.... I dropped the Photon app when I read you had to put tissue paper over the lens, how the feck do you trust a reading like that ....  Still use their online calculator

 

So I went with the PPDF meter App along with the UNI-T UT383 BT light sensor ... no tissue paper. With a combo of intensity and light height and the online calculator, I have found a happy medium.

 

Mine now 5 weeks flowering with PPFD of 860 and DLI 37.2 whereas the ideal is 36 and PPDF is ideal ... and my lights are still running at 50% with a light height of 8" .... sounds low but with only 50% output there seems to a good balance, and low heat for the buds ... maybe i will have to go 100%, we'll see

 

I would imagine that if you're running full blast your lights will need to be around 18" high.

 

I had trouble with all this with my 1st grow with light heights and intensity, when i got the sensor and new app plus the calculator i started to learn very quick what's good and not good .... IMO it's about getting the light height and light intensity right... it's working OK for my 2nd grow

 

[MidgeSmith]

3 hours ago, MindSoup said:

Photone? Is that the app that tells you to put a piece of paper over your phones light sensor? Not sure I'd listen much to them to be honest. 

 

Just like most other things with growing there's no set answer. How much light you should/can give depends on a multitude of factors, it's all part of the relationship between different environmental parameters. for Instance if it's very warm and very humid and high in co2 you can/should give a lot more light than if it's cold, dry and low in co2 etc

 

This guy will tell you everything you could ever need to know about lighting . Have a look for his other video's and interviews etc, he's a proper actual botanist that works for NASA and such and has been growing cannabis indoors since the 70s or something like that, pretty much the world's leading expert on indoor cultivation. 

 

 

 

 

Thanks for your answers, it is good of you to take the time to supply them. I hear your protests and accept what you say is quite likely. There are, after all, more people who back the conventional way to grow vs this suggestion and those people sound more likely to be correct to me too!!  However, I feel like adding a little more to each point that the same time.  I am looking really to hear if ANYONE has actually tried this, counter-intuitive as it might sound.

@MindSoupYeah, I've watched that a few times in the past. As you say, he is pretty much The Don of lighting. It might be worth considering that he doesn't necessarily contradict what Photone suggests and what I am discussing. I suppose he does in that he talks about the higher the PPFD the better up to quite a high value, but those targets might be completely cool maximums without noting that ramping to and from the number of hours and the intensity of light could be beneficial. Maybe because he knows they are not, maybe because its another step on from beginner to advanced.

 

Again, looking at the natural model, for good or bad, less hours of light without a huge leap in light energy will result in a huge drop in DLI.  Should you massively boost intensity to retain the same DLI at the start of flower as you had at the end of veg?  Conventional grow approaches say yes, contrary to what happens in nature, so maybe.  However, maybe it is actually stressing the plant unduly to try to give it the same amount of light in 2/3rds of the time.  Maybe keeping light intensity similar but dropping the light hours is not so ludicrous.

 

Re: Photone, I think Photone's product is pretty good to be honest, though I understand y our objections. I never bothered putting the tissue over the lens! I know, maverick and in theory less accurate, though I don't agree regarding the paper over the lens being inaccurate, as they state the paper weight and type - 80 g/m² white printer paper.  That's quite a tight specification and uniform enough to provide a predictable result. More predictable perhaps than the lens input of different phones. Maybe I should listen to myself and run tests with that paper on (EDIT: decided that I will as it will give me an excuse to raise the DLI again), but after calculations, the phone light meter reads pretty similarly to my lux meter (I didn't afford a proper PAR meter), so I am happy enough with that.

 

I just want to interrupt myself to point out that I have tried going over the DLIs recommended by photone (which I state again as it is my preferred way to guage if the settings I usually choose are still outputting the amount of light I use) and I had to shade one of the plants as it started getting noticeably stressed. After shading it, the damage stopped. Though it was only once, it was enough to reinforce my opinion of photone.

 

As I say, the key part for me is the accidental experiment that some folks in the USA had when they had a bad batch of lights and they found that lower light intensity during the start of flowering, gradually building up to the 6th/7th week of flowering and then dimming down a bit, encouraged better buds than they had with maximal light levels through the whole process.

 

@handysmoker I get radiation damage lower than 12" even with my lights turned down.  I don't quite understand why, but I have seen others having similar issues. Must be more radiant radiation than radiant light at some threshold, though I don't pretend to understand.

 

You are quite right about getting the intensity and height right. I'm glad my phone without tissue seems to do it so well with Photone.  I'm not so much refuting what you and Mindsoup have said, but my mileage varies.

 

I KNOW, I KNOW

So that is two people so far who haven't tried reducing the DLI at the start of flowering and working it up - same as I haven't in the past.  I wonder if there is anyone here that has?

 

I TOTALLY get that it sounds counter-intuitive and why, more energy in (up to the point of toleration) more mass out. At the same time, I can understand the rationale of the alternative way of doing so and that unless people try it for themselves, they won't know if it is more bro-science or if there is something to it and work out why it can work, if it can.

 

After all, when we flip out plants, we are skipping time where in nature the plants would see a gradual decrease in light levels and therefore to an extent DLI as the number of hours of light decreased and the intensity didn't increase proportionally, so it isn't as crazy as it sounds.  Simultaneously, what is natural is NOT always what is most productive and that's why I sit above the fulcrum with my hand holding my chin and wonder...

Edited November 18, 2023 by MidgeSmith

[MidgeSmith]

I am tempted to carry on experimenting with this, but I might defer going the whole hog for a while.  I am slightly wavering based on the majority opinion, but also because I know that as cannabis can handle certain light levels, it seems like it would be productive to be close to those levels.

 

This time around, I think that I will increase my DLI day by day, from current light intensity (as it was at veg) to an increased intensity which reaches the same DLI by the end of the week as I had duting veg. That way, I will be allowing for an adjustment period.

 

If I had the tech, I'd have hours of daylight, light intensity, temps, humidity and everything else adjusted daily to make smooth curves, because I love that kind of automation, but I can't afford to do that at the moment, so small adjustments to try to limit stress are all I can be bothered with.

[Military Grade]

Mine Photone was 1% out using a A71 without tissue paper.

 

But found once you get to know your light you never need light metres again.

[MindSoup]

2 hours ago, MidgeSmith said:

MindSoupYeah, I've watched that a few times in the

 

The bit of the video that I was more focused on was the part that followed on from what I was saying about the relationship between all the different environmental parameters. You can't run your lights off a chart, it's like saying how much to water and how often, the answer is "it depends".

 

In theory, if you could get your parameters on point you could give them 1000+ from day 1, but by doing that you'd be walking a knife edge, most home growers don't have precise enough control over their environment. It's a lot easier (and cheaper) to match the light intensity to the environment, not to drive the car as fast as it will go redlining every gear change so to speak, unless your a really good driver of course. He doesn't really go too in depth on that particular subject in this video TBF, maybe I was thinking of a different video. 

 

But yeah, don't listen to me, listen to Bruce .

 

[MidgeSmith]

Point taken.  However the reason I think there is leeway is that we are not talking about how to max it, so much as the theory that the plants like to be under capacity at that transition stage. Naturally plants do best with everything in the right proportions and at the right levels.

 

However the idea that though they can cope with much more light during the transition period and stretch, they might benefit from not having it, resonates a bit.  It's like the stress of defoliation - less leaves but more growth... really?!

 

Anyway, just an idea and interesting to me.  Thanks  for indulging my theory query, cheerily.

[handysmoker]

2 tents .... 4 plants the same strain ... same lights in each tent .... would be a good way to do a comparison grow

 

Would be interesting to see what the results would be

[catweazle1]

18 hours ago, handysmoker said:

Hey @MidgeSmith.... I dropped the Photon app when I read you had to put tissue paper over the lens, how the feck do you trust a reading like that ....  Still use their online calculator

 

So I went with the PPDF meter App along with the UNI-T UT383 BT light sensor ... no tissue paper. With a combo of intensity and light height and the online calculator, I have found a happy medium.

The function of the white paper is the same as that white disc on the UT383.

Edited November 19, 2023 by catweazle1

[handysmoker]

5 minutes ago, catweazle1 said:

The function of the white paper is the same as that white disc on the UT383.

Yeah, I got that .... it's what we would use to call a "Heath Robinson" job ...

[catweazle1]

That dip in the DLI schedule seems to be to induce a stronger flowering response.

Edited November 19, 2023 by catweazle1

[MidgeSmith]

35 minutes ago, catweazle1 said:

That dip in the DLI schedule seems to be to induce a stronger flowering response.

That would make sense and the anecdote that I am referring to from the commercial grower makes it sound like it works rather well.

 

As handysmoker says, I would like to see a side-by-side because I'd quite like to try it. My feeling this time is that slowly upping the light intensity is probably good as a stress reduction mechanism at a time when they are switching over and don't need to be roasted at the same time as they are getting themselves together.

 

The thing is though, if it worked really well, reliably, you'd think more of the commercial folks would have tried it.  They're not averse to making a buck - so I hear - and it only takes 2 small rooms of clones to R & D it.

[MindSoup]

 

43:47 

 

I know he doesn't address your question directly, but the fact he doesn't mention it speaks a lot IMO, if anyone would have tried it in a laboratory setting it would have been Bruce.  I'm sure there's another interview somewhere that he does go into it a bit more... 

Edited November 21, 2023 by MindSoup

[MidgeSmith]

Well that's terrific!  it shows that the fastest growth can be achieved with the maximum light the plant can cope with. It doesn't necessarily rule out lower light building up to maximal having a similar result, but it makes it seem unlikely.

 

Thanks for taking the time Mr Mindsoup! Like you, I trust in Dr Bruce Bugbee.