The far red thread

[nachooo]

No, correlation does not imply causation. The fact that plants grown in a 24h rhythm correlate to a 24h rhythm doesn mean we are stuck with that rhythm.

I've seen people grow Cannabis on a 36 hour day or shorter days than 24h. All of those worked fine too. The rhythm simply adapts to the new day length.

That only costs more. There is an economical optimum and running the leds "hyper efficiently" is not economically optimal. Besides, you still have the DLI problem which nachoo referred too. So either way, you still end up paying more for the same DLI.

It is true that to obtain about a 15% more efficiency you have to double the number of leds or used more efficient leds (like a vero 29 instead every vero 1 which is cost expensive except in little spaces...Althought with the new chinese LM561C samsung leds strips at this low prices...the game is gonna change a lot... 15 meters of strips will provide almost 1000 PPFD for 50 $ in a 3x3 tent...
the drivers for this leds are cheap...also the better diffused light will help a lot with heat and light stress in the upper canopy allowing to up the PPFD more safely.

 

[wietefras]

@nachoo, Don't forget photosynthesis in plants is less efficient if you increase the intensity a lot. If you were using 1000PPFD average intensity for12 hours before, then you'd need 1500PPFD to get the same DLI in 8 hours. The efficiency drop-off from 1000PPFD to 1500PPFD is quite high. Or rather the extra yield from increasing the intensity in that range is quite low.

The Chandra chart indicates you'd get only get 7% to 9% more yield when you increase the PPFD from 1000 to 1500. I analysed the YOR database (with data on 175 grows) and arrived at a slightly more linear trend, but then still it would indicate only around 14% increase in yield for 50% more light (1000 to 1500).

Perhaps a solution might be to go increase the surface area by 50%? Then the PPFD would stay the same and the yield should go up by 50%. Then corrected for lighting only 8 hours instead of 12 you'd be back at the same yield overal.

 

[nachooo]

@nachoo, Don't forget photosynthesis in plants is less efficient if you increase the intensity a lot. If you were using 1000PPFD average intensity for12 hours before, then you'd need 1500PPFD to get the same DLI in 8 hours. The efficiency drop-off from 1000PPFD to 1500PPFD is quite high. Or rather the extra yield from increasing the intensity in that range is quite low.

The Chandra chart indicates you'd get only get 7% to 9% more yield when you increase the PPFD from 1000 to 1500. I analysed the YOR database (with data on 175 grows) and arrived at a slightly more linear trend, but then still it would indicate only around 14% increase in yield for 50% more light (1000 to 1500).

Perhaps a solution might be to go increase the surface area by 50%? Then the PPFD would stay the same and the yield should go up by 50%. Then corrected for lighting only 8 hours instead of 12 you'd be back at the same yield overal.

I understand..but sadly my limitating factor is space..that is the reason of trying to high the PPFD...Probably I will end using a middle aproach..10/14 with far reds and no more than a 1200 PPFD... instead of driving the cobs higher I will add samsung new leds stripes as side lighting...I have the feeling that if some percentage of total light came from side lighting..probably the plants could manage more PPFD or use the same more efficiently...less leaf temperature in the upper canopy and less chance of photoinhibition...also bigger intracanopy buds

 

[wietefras]

I understand..but sadly my limitating factor is space..that is the reason of trying to high the PPFD...Probably I will end using a middle aproach..10/14 with far reds and no more than a 1200 PPFD... instead of driving the cobs higher I will add samsung new leds stripes as side lighting...I have the feeling that if some percentage of total light came from side lighting..probably the plants could manage more PPFD or use the same more efficiently...less leaf temperature in the upper canopy and less chance of photoinhibition...also bigger intracanopy buds

Ah ok. Makes sense.

Or perhaps vertical? You'd need less of a footprint for the same "surface area"

But yeah, probably better to try this with a more conventional grow first. Shortening the day and increasing the intensity by a lot is probably already quite a change.

 

[NewBKind]

I just got 18 cxm22 3500k 90cri luminus cobs for a 4x8 area. What would you use in this space for a good IR source

 

[randydj]

I just got 18 cxm22 3500k 90cri luminus cobs for a 4x8 area. What would you use in this space for a good IR source

Do you mean far red? what is the purpose for them?

 

[NewBKind]

Do you mean far red? what is the purpose for them?

I would like to go 10/14 and increase my yield with IR

 

[NewBKind]

I would like to go 10/14 and increase my yield with IR

Is far red slang for infrared

 

[CobKits]

"far red" is an LED term for 730nm-ish mono leds

as opposed to "photo red" (660ish)

"infrared" is a scientific description of wavelengths above 700 nm up to ~1mm. the vast majority of which is not usable for photosynthesis

 

[randydj]

Is far red slang for infrared

I think you mean 14/10 - day/night. by using the 730 nm lights for 15 minutes at lights out the plants respond as if 12/12. So you have the right idea. Technically depending on where you look 730 nm is at the bottom of IR but as growers we call it Far Red.
What you ar looking for is 730 nm SemiLeds. Go here for how to DIY. Search on 3 watt far red SemiLeds to buy the parts. 9 of them should be plenty for your space.

 

[NewBKind]

"far red" is an LED term for 730nm-ish mono leds

as opposed to "photo red" (660ish)

"infrared" is a scientific description of wavelengths above 700 nm up to ~1mm. the vast majority of which is not usable for photosynthesis

As always man you come through with the best answers. AWESOME data for me to learn from

 

[Nutria]

I got 10w of 730nm and 10w of 660w, both cobs will be used in a 2x2 tent to supplement 4xCLU048-1212 80cri.
Do you think I will use too many watts for the 730?
I am looking to achieve a shorter flowering time

 

[NewBKind]

I got 10w of 730nm and 10w of 660w, both cobs will be used in a 2x2 tent to supplement 4xCLU048-1212 80cri.
Do you think I will use too many watts for the 730?
I am looking to achieve a shorter flowering time

I also want to achieve this with cobs in my 4x8 running 18x cxm22 3500k 90cri. I hope someone can tell me what I need for this space that I can use cob or something equivalent in efficiency to achieve

 

[BuddyColas]

I think you mean 14/10 - day/night. by using the 730 nm lights for 15 minutes at lights out the plants respond as if 12/12. So you have the right idea. Technically depending on where you look 730 nm is at the bottom of IR but as growers we call it Far Red.
What you ar looking for is 730 nm SemiLeds. Go here for how to DIY. Search on 3 watt far red SemiLeds to buy the parts. 9 of them should be plenty for your space.

Have you ever tried 14 on 10 off with 730s at bedtime right at the flip?

 

[nachooo]

Have you ever tried 14 on 10 off with 730s at bedtime right at the flip?

I tried it with a pure sativa and an indica dominant strain (75%), things were ok, but the sativa strain developed a few bananas at the end of the flowering time, this strain never did that before..I used same clone.. But those bananas appear the last days...like when you make rodelization..Ithink tht is the term used..for extended periods of flowering time.. Anyway no seeds or preseeds were formed. The indica strain gave me better much results than with 12/12 (same clon)

 

[BuddyColas]

I tried it with a pure sativa and a indica dominant strain (75%), things were ok, but the sativa strain developed a few bananas at the end of the flowering time, this strain never did that before..I used same clone.. But those bananas appear the last days...like when you make rodelization..Ithink tht is the term used..for extended periods of flowering time.. Anyway no seeds or preseeds were formed. he indica strain gave me better much results than with 12/12 (same clon)

I was thinking it SHOULD work, but nothing like actual experience. Thanks.

 

[nachooo]

I tried it with a pure sativa and a indica dominant strain (75%), things were ok, but the sativa strain developed a few bananas at the end of the flowering time, this strain never did that before..I used same clone.. But those bananas appear the last days...like when you make rodelization..Ithink tht is the term used..for extended periods of flowering time.. Anyway no seeds or preseeds were formed. he indica strain gave me better much results than with 12/12 (same clon)

I was thinking it SHOULD work, but nothing like actual experience. Thanks.

Forgot to say that the sativa clon, take about 15 days more to finish with a 14/10 with far reds than with 11/13 also with far reds but the quality was better.. and a little more potency.

 

[BuddyColas]

Forgot to say that the sativa clon, take about 15 days more to finish with a 14/10 with far reds than with 11/13 also with far reds but the quality was better.. and a little more potency.

Did your indica strain finish faster on 14/10?

 

[nachooo]

Did your indica strain finish faster on 14/10?

No, it finished about 5 days later than a 12/12 without far reds...think that using far red for flower time reduction works in 12/12 and 11/13..10/14... but not in 14/10... Maybe 13/11 or 12,5/11,5 is the sweet spot to gain some more production and also reduce flower times... of course each strain is different...

 

[GroErr]

No, it finished about 5 days later than a 12/12 without far reds...think that using far red for flower time reduction works in 12/12 and 11/13..10/14... but not in 14/10... Maybe 13/11 or 12,5/11,5 is the sweet spot to gain some more production and also reduce flower times... of course each strain is different...

I've been using 660nm and 730nm initiators for a couple of years. Have run from 12.5/11.5, 12/12, and 11.5/12.5 (current). Regardless of strain, the initiators didn't seem to do much if anything at all at reducing finish times until I got to 12/12, then much faster finishing at 11.5/12.5 which is likely where I'll stick as there's been no notable difference in yield.

Biggest difference with same strain/clone (known control clones were used on every run) was as long as 63 days at 12.5/11.5 and down to 50 days at 11.5/12.5. The most significant difference/reduction in finish times was after changing to 11.5/12.5.

imo initiators are questionable (to reduce finish times) unless you're running 12/12 or less (11.5/12.5, 11/13) from what I've seen. I also believe the shorter lights-on times have more of a role in reducing finish times than initiators alone. Will be validating that next by running some known clones at 11.5/12.5 with no initiators.