The far red thread

wietefras

wietefras

Well-Known Member
Well from the research papers/results I saw, they seem to go for an FR dose of 3000µmol to 4000µmol per m2.

Many strains can go fine for less than 12 hours of dark even without additional FR light, but others will really need at least 12 hours of dark. So depending on the strain, less would work too, but then it's difficult if not impossible to be sure what the actual needed dose for each strain is.

So, I'd rather be safe than sorry and go for that range of 3000µmol to 4000µmol per m2

A single Osram OSLON SSL 730Nm @ 350mA will produce about 1.4µmol/s of FR light. So that would need to run for 3000µmol / 1.4µmol/s = 2142s (or 36 minutes) to produce at least 3000µmol. I have 4 of those per square meter, so I keep them on for 10 minutes.

Perhaps 15 minutes would be even better to hit the high end of the range and to account for wall losses.
 
C

confined

Member
Would you still see the Emerson effect by using the far red at lights out and keeping the light schedual at 12/12 all the way through still?
 
wietefras

wietefras

Well-Known Member
@confined , No, the Emerson effect is when you give the plants a combination of red and far red light. That's something you would get when the FR leds are on together with the main lights. Adding FR during the dark period is only aimed at phytochrome conversion.
 
Heil Tweetler

Heil Tweetler

Well-Known Member
wietefras said:
@confined , No, the Emerson effect is when you give the plants a combination of red and far red light. That's something you would get when the FR leds are on together with the main lights. Adding FR during the dark period is only aimed at phytochrome conversion.
Click to expand...

are you clear on the varying efficacies of 730nm vs other bands in the far red spectrum? When i looked into the emerson effect I searched for a precise combination of bands that fully elicit the emerson effect. I'm still not sure if 700nm is more effective than 730? Are they equally effective?
 
wietefras

wietefras

Well-Known Member
Heil Tweetler said:
are you clear on the varying efficacies of 730nm vs other bands in the far red spectrum? When i looked into the emerson effect I searched for a precise combination of bands that fully elicit the emerson effect. I'm still not sure if 700nm is more effective than 730? Are they equally effective?
Click to expand...
700nm is the peak for photosystem 1 and 680nm for photosystem 2. So 700nm should be better to excite PS1.

However 700nm is not something you can supplement with mono leds. Or at least I haven't seen any mono's that will produce that.

For phytochrome conversion (flower induction), 730Nm is best.
 
Rahz

Rahz

Well-Known Member
A combination of greater than 680 and less than 660, so 680-700nm is probably going to be the most useful for the Emerson effect. Whether 730nm is a substitute for that I'm not sure but it doesn't seem to be responsible for a lot of photosynthesis so I wouldn't assume it would be a useful driver of the Emerson effect.
 
P

Photon Flinger

Well-Known Member
wietefras said:
Well from the research papers/results I saw, they seem to go for an FR dose of 3000µmol to 4000µmol per m2.

Many strains can go fine for less than 12 hours of dark even without additional FR light, but others will really need at least 12 hours of dark. So depending on the strain, less would work too, but then it's difficult if not impossible to be sure what the actual needed dose for each strain is.

So, I'd rather be safe than sorry and go for that range of 3000µmol to 4000µmol per m2

A single Osram OSLON SSL 730Nm @ 350mA will produce about 1.4µmol/s of FR light. So that would need to run for 3000µmol / 1.4µmol/s = 2142s (or 36 minutes) to produce at least 3000µmol. I have 4 of those per square meter, so I keep them on for 10 minutes.

Perhaps 15 minutes would be even better to hit the high end of the range and to account for wall losses.
Click to expand...

Is that per what? m2? cm2? of leaf? grow area?
 
C

confined

Member
wietefras said:
@confined , No, the Emerson effect is when you give the plants a combination of red and far red light. That's something you would get when the FR leds are on together with the main lights. Adding FR during the dark period is only aimed at phytochrome conversion.
Click to expand...
My bad, nooby noob here :P you just got my head around it though. This shits been itching at my brain for past 4 weeks! Cheers mate
 
Rusher

Rusher

Well-Known Member
Excellent thread, aside from the bitching and dick-slinging. Inspiring enough for me to take the plunge. I'm running 4 Vero29 @3500 pushed to 85w each (340w total @37.7 w/sqft), and just bought this from rapidled:

http://www.rapidled.com/12-solderless-led-retrofit-kit-non-dimmable/

I running a small space, 3'x3'x6', but at that price, I ordered an extra driver and will split the set into an 8 light set for my flower room, and a 4 light set in my veg room for those strains that need some stretch in veg. Some of the indica doms that I've run have started the 5th/6th node while being less than 3" tall. I like my plants squat, but that's unacceptable. I'm also looking forward to reduced flowering time; it should be an interesting experiment.

Thanks @Rahz , @captainmorgan and the other main contributors.

Cheers!
 
GreenSanta

GreenSanta

Well-Known Member
Sorry I dont have the time and patience to read the whole thread.

What about the perpetual growers? when there are always plants at various stages of growth, would I still benefit from far red?

Would it hurt to have it on 13 hours while the rest of the lights on for 12 hours?

Or should I stick with proven lighting schedule, it seems very expensive of a light to have it on only minutes every day.

Right now I was looking at those :

http://timbergrowlights.com/grow-light-kits/osram-oslon-ssl80-kits/
or this http://www.rapidled.com/far-red-initiator-puck/
 
iHearAll

iHearAll

Well-Known Member
GreenSanta said:
Sorry I dont have the time and patience to read the whole thread.

What about the perpetual growers? when there are always plants at various stages of growth, would I still benefit from far red?

Would it hurt to have it on 13 hours while the rest of the lights on for 12 hours?

Or should I stick with proven lighting schedule, it seems very expensive of a light to have it on only minutes every day.

Right now I was looking at those :

http://timbergrowlights.com/grow-light-kits/osram-oslon-ssl80-kits/
or this http://www.rapidled.com/far-red-initiator-puck/
Click to expand...
You could DIY one for a fraction of the costs with less quality leds. I doubt the efficiency ofcree diodes at this scale makes much of a difference.

Anyway, the length of time and pattern of when its on makes w difference in the effect. Supposedly. Im trying a few grows now with deep/far reds.

I think if you leave the lights on full time it just causes stretching. Not sure about the flowering speed though
 
randydj

randydj

Well-Known Member
GreenSanta said:
Sorry I dont have the time and patience to read the whole thread.

What about the perpetual growers? when there are always plants at various stages of growth, would I still benefit from far red?

Would it hurt to have it on 13 hours while the rest of the lights on for 12 hours?

Or should I stick with proven lighting schedule, it seems very expensive of a light to have it on only minutes every day.

Right now I was looking at those :

http://timbergrowlights.com/grow-light-kits/osram-oslon-ssl80-kits/
or this http://www.rapidled.com/far-red-initiator-puck/
Click to expand...
If you have the patience to wait for your buds to ripen fully then you have time and patiences enough to learn what far red is all about. It is complicated and does different stuff at different times.

The Phytochrome System and Red Light Response.

Read this: https://www.boundless.com/biology/textbooks/boundless-biology-textbook/plant-form-and-physiology-30/plant-sensory-systems-and-responses-184/the-phytochrome-system-and-red-light-response-701-11926/

and this The Emerson Effect.

https://en.wikipedia.org/wiki/Emerson_effect

These are short not overly technical explanations on what far red can do.
 
nfhiggs

nfhiggs

Well-Known Member
confined said:
My bad, nooby noob here :P you just got my head around it though. This shits been itching at my brain for past 4 weeks! Cheers mate
Click to expand...
In a nutshell - the Emerson Effect is this:

Under WEAK light, below 400 umoles, photosynthesis is more efficient if both 680 nm and 700 nm light is given, than if either frequency alone is given - its a synergistic effect. The effect diminishes rapidly as light intensity increases. Since we do not generally try to grow cannabis under such weak light conditions, the Emerson effect really does not come into play with respect to growing. It is my opinion that the Emerson Effect is simply an evolutionary holdover from when algae was the dominant plant lifeform and was growing under water, where longer wavelengths tend to penetrate deeper. The effect would allow algae to grow at deeper depths.
 
wietefras

wietefras

Well-Known Member
nfhiggs said:
In a nutshell - the Emerson Effect is this:

Under WEAK light, below 400 umoles, photosynthesis is more efficient if both 680 nm and 700 nm light is given, than if either frequency alone is given - its a synergistic effect. The effect diminishes rapidly as light intensity increases. Since we do not generally try to grow cannabis under such weak light conditions, the Emerson effect really does not come into play with respect to growing. It is my opinion that the Emerson Effect is simply an evolutionary holdover from when algae was the dominant plant lifeform and was growing under water, where longer wavelengths tend to penetrate deeper. The effect would allow algae to grow at deeper depths.
Click to expand...
Ah, that's a good addition to the theorem.

It would work for plants too I guess. Lower down below the plants there is a higher fraction of FR light too
 
Nugachino

Nugachino

Well-Known Member
Does anyone know what kind of light for bloom boosting would suit a roughly 1.8 sq foot grow space? I've got a 180w 3500k cob set.
 
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