Veg lighting W & light cycle - Whole grow efficiency quest

Advanced Techniques
#1

Hello boys and girls,

The Quest is whole grow efficiency. Now focusing on veg lighting and specifically on how much light per area and what light cycle to use.

I put this under advanced tech section as in FAQ the efficiency was under advanced tech section.

I have looked over couple of sites but I have found fairly little info on how much light to use in veg stage and should the amount used change over the course of veg grow.

While true watts (what is pulled from outlet) are not perfect … it is fairly good and simple. As for area … sq ft … sq m … m2 all good for me. I will try to use sq ft as many users (I guess) are used to imperial system rather than metric.

In rooting phase only very little light … In flowering without co2 35w/sqft a good start point, and after 60w/sqft bit overkill.

While most light setups will work more or less… I do strive to find the sweet spot and rather with less iterations than with more.

Someone pointed out that veg stage is important as plant builds most mass during it.

My guess would be to start iteration with ~ 45w/ sqft. Comments, opinions, recommendations on this?

On light schedule my starting point might be around 8/4/8/4 8on4off. Comments, opinions, recommendations on this? Reason being that the 4h night might be enough for the plant to utilize stored resources (that were build up during the day). Naturally looking to save on energy bill during 8h off.

I have intentionally left out what type of light to use… or what is best… there are many discussions on those already and we have to focus our attention.

Ciao

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#2

sounds like a plan!

@Fuel and @Palindrome are all about those crazy light cycles so ill let them speak on that.

but great first post! let’s see some pics and welcome to OG

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#4

45 watt will be okay, I find 55 Watt sqft for HPS flowering. Is the sweet spot for most strains, grown without Co2 supplements. For veg 45 watt sqft, should give you good growth.

Im new to LED, but doing some tests. So far I have only tested cheap china strips, mainly for veg to cut heat.
I found out 20-25 Watt sqft is enough for slow veg, they didn’t steach, just grew slow.
Flowering under this, was far from enough. Still hit 0.77 gpw, but all of it popcorn buds.

About light cycles - 8/4/8/4 will work fine, should just veg slower. I am doing some tests on 6/6/6/6, and was contacted by a grower who do 8/4/8/4 during summer. Due to heat issues, and it’s been working fine for him.
I have been researching on short-day plants like cannabis, about the hormone triggers and production. And that got me on to the idea of the 6/6/6/6 cycle, might not just save energy. But the first trial done by Fuel, showed some very interresting root developing going on. That was very different, compared to it’s sisters under 18/6.

Changing the light cycle, change the plants metabolism. Studys also show, short-day cultures under low light settings. Make bigger, thiner leafs, that are more Photosynthetically active cell’s.

Giving me the crazy idea, that this might be something worth exploring. Keeping clones short, but expand their root system and make the leafs more photosynthetically active. Up to the point, where I flower them out in a SOG under a high sqft wattage 12/12 cycle. Small, but maybe spring loaded to explode. All done under light cycles, that only use 12 hours of light per day.
It might also turn out to be shit, frying the fan leafs, stunning the clones and/or other unexpected things.

You can find my Hack shack thread in this subforum or thru my profile, and welcome to Overgrow.

Happy growing

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#5

Thank you for welcoming words and comments !

standard demo effect… as soon as I post “cant find…” … I actually find a bit more info…

Robert Bergman gave the guidelines of 400w for 13sqft in veg and 600 for 13sqft in flower … that would be 31w for sqft in veg and 49 in flower. …

I guess I will aim for 45w/sqft. Naturally a light that lights only the area where plants are so small area first and bigger light for mid/late veg when there is lager canopy to catch more light.

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#6

Jumping in for the ride always looking for savings where I can…

I like the gaslight technique with leds though 12 on - 5 off- 2 on - 5 off then add in an additional hr off each week until hit 10hrs then back up to 13 hrs for the remainder of flower though before I do it again, I want to add infrared to start 5min before lights off and turn off 5minutes after lights off …totally sucked for traditional hps and haven’t tried it with the CMH… yet…the 6/6/6/6 sounds interesting and a nice balance in dark/light periods

As far as watts/sqft…imho, traditional hps needs 40w/sqft, cmh needs 35w/sqft and newer leds (solstrip, quantum board, cobs) needs 30w/sq ft to perform well. Anything less will produce just smaller and on the airy side

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#7

Cool … far red spectrum effect on night cycle is ‘on my radar’ or ‘on my to do list’ … regretfully several steps away before I can test/ try it out … timer issues as you said.

Big advantage of this is in flowering … Not sure if benefits (afaik them) are worth the effort in veg stage.

With standard supermarket mechanical timer you can get down to 15 min on rest off slot… just tricky to get main light timer and far red timer to run in sync.

arduino/ rasberry offers one solution but that is a subject worthy of its own thread.

Couple of notes… You speak of infra red while I speak of far red. …We might be talking about same thing but it is my understanding that IR spectrum alone is not enough to trigger the ‘fast sleep’ effect … as I coined it in my notes. - and yes… plants do ‘work’ during night.

Second was that the study/ experiment I read used only short bursts before night cycle … not continuous 15 min and nothing after lights out. … dunno if/ what difference this might make.

just passing on what I read, no experience.

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#8

I too have no experience messing with light spectrum’s outside of how the lights come though had been watching a few on various forums playing around with it…before my computer crashed a couple months ago, I had an extensive list of research on this so just going by memory…

Emerson effect increases the rate of photosynthesis using deep red though it drops off in efficiency (red drop effect) unless it is countered with short bursts of infrared one right after the other

Blue = chlorophyll
Red = stretch/branch
Deep/far red = circadian rhythm signaling for faster sleep response
Infrared = faster bud stimulation, counters red drop effect

So in theory it would go something like:

Germinating/seedling: blue with small amount of red…increasing say, 30-60 minutes a week
Veg: blue with amount of red steadily increasing
Mid/late veg: both blue and red is used at the same time. Once this happens, expose to far red…I like transitions so 5min before red goes off til 10minutes after
Early flowering: small amount of blue using mostly red, continue to expose to far red, start exposing to infrared for 5 minutes before and after deep red is off (10 min total) and uvb for 30 minutes at the peak of midday increasing each week…some start uvb in veg while others only do short bursts in flowering
Mid flowering: Stop using infrared at budset…uvb “should” be at the same amount of time as red and far/deep red for increased trichome production
Late flower: Stop using uvb

Of course there are other spectrum’s plants use and should be included for overall balance…iirc, namely green and white. I am probably way off base and will need to go back to research for accuracy as well as, figure out how to use it with the gaslight technique to save energy without dropping off in efficiency…there were a couple that I believed were on the right track as displayed in their plants though forget who they were/are and which forum and don’t remember what light cycle was used.

Once I have more time (or increased insomnia nights), I will look all of this up and attempt a version that makes the most sense and see what happens… I just upgraded my hps to cmh so it’ll be awhile before I play around with leds other than what I have now

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#9

Specifically regarding the Emerson effect, my understanding is:

Far red (PS I) + red (PS II) = Emerson enhancement effect.
Just far red without red = red drop at wavelengths exceeding 680 nm (PS I).

The limit to “far red” has been shown experimentally in at least one paper to be up to 840nm which, at that wavelength, is mid-infrared radiation (700-1000nm). However, far red is also considered to be between 710 and 850 nm. So there is a bit of overlap/variation in the definitions of where far red ends and infrared begins.

It is not clear to me if there is an actual differentiation between far red and the beginning of the infrared spectra for PS I. Far red should have the same effect as infrared up to 850nm according to that study (maybe the efficiency changes along the curve). As such, I’d think far red should do the job without worrying about infrared.

I would be interested in references that note specific differences between the far red and the infrared regions. In particular if my understanding is inaccurate.

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