The far red thread

Randomblame

Well-Known Member
same DLI as photos
Yepp! Plants grow more efficient with low intensity and especially with automatics it leads to great results.

ppfd-charts.png


With 500μMol/s PPFD the grow rate is 70%, with twice as much it's only 90%. That means low intensity is more efficient... to a certain degree.
Photosyntesis under different temps and intensities.jpg

Ambient temperature also makes a big difference. A plant getting 500μMol/s/m² @30°C grows as fast as the same plant getting 1500μMol/s/m² at only 20°C.
 

Randomblame

Well-Known Member
Give them 500μmol/s/m² and keep the temperature between 25 and 30°C. You probably need to set your extractor fan to the lowest level...
Positive side effect, with lower intensity it is easier to keep a good VPD. High intensity quickly leads to dry air and you need a humidifier.
 

Old ninja

Active Member
Plants grow more efficient with low intensity and especially with automatics it leads to great results.
That's what I'm talking about. That's why it is detrimental to make days shorter, but small changes make small differences usually.
Ambient temperature also makes a big difference. A plant getting 500μMol/s/m² @30°C grows as fast as the same plant getting 1500μMol/s/m² at only 20°C.
Very important!!
with lower intensity it is easier to keep a good VPD. High intensity quickly leads to dry air and you need a humidifier.
With higher VPD,you need lower EC
 

Rahz

Well-Known Member
This is a good question which i havent seen a definite answer. Standard logic says no-no. But far red also seems to speed up the transition process. When @Rahz did his cri shootout the 90 Cri spectrums, with more far red, had more stretch in vegg but had less stretch in the transition phase: plants went to flower about 12'' taller than the 80 cri, but after stretch they were only about 6'' taller and strech stopped quicker. That is not to say adding only far red to 80 cri will do the same.
I havent tried myself, but id be looking at incorporating end of day far red the last week of vegg, to speed the transition.
I've replicated those results several times now. It varies a little each time but the lower CRI always does some catch up in the flower stage.
 

Randomblame

Well-Known Member
What's the point having them on during the light period?
I don't see any benefit doing so.
Maybe it's not necessary, but my clocks are not synchronized and therefore I let it go on a little earlier. The effect seems the same, at least I see no difference when one clock comes slower over the weeks.

The important thing is that they get it at the end of the day. I do not know how much far-red residual radiation is left when the sun goes down. I bet little! That means for me, they get most of the far red when it's still bright.

I think far-red triggers phytochromes and there is no need for complete darkness all the time but it could of course be wrong.

I can only say, it works for me!
 

GroErr

Well-Known Member
@GroErr it's possible to harvest 42-45 days strain at day 37-40? With far red option.
Or are we talking about 5-7 days reducing on 70 days strains?
You might knock off a few days with initiators and 11.5/12.5, possibly down to 40, doubt you'd knock off a whole week if they're already finishing that fast. But I have 4 phenos that finish in around 49-51 days that were typically 54-56. Rarely go more than 56 with the hybrids I'm running other than a pure sativa like Panana (even there it's stated at 11-13 weeks and finished in 10 & 11 weeks) and I cycle 12-15 strains on average.
 

Old ninja

Active Member
What about the other direction? Longer days and shorter nights with EoD, like 13/11? In theory it doesn't reduce flowering time, but increases yield. Is this true?
 

nachooo

Well-Known Member
What about the other direction? Longer days and shorter nights with EoD, like 13/11? In theory it doesn't reduce flowering time, but increases yield. Is this true?
I have done the two ways, with same sativa clones:
clasic 12/12 takes about 10 weeks of flowering time
13/11 + far red... 11 weeks , good production, some male flowers appear at the end..
10/14 + far red... 8 weeks, good production (I added more light to mantain DLI to keep production rates)
For sativa strains I think 10/14 plus far red is better. for quick fowering indica strains I prefer 13/11
 

GroErr

Well-Known Member
What about the other direction? Longer days and shorter nights with EoD, like 13/11? In theory it doesn't reduce flowering time, but increases yield. Is this true?
Best overall yield I got was running 12.5/11.5 and low wattage on one end of the room like 22w.sq./ft. Those clones got 10-15% more than usual, but it took forever to finish, like 2 weeks past usual finish times. Wasn't worthwhile for me but I'd rather flip more/faster for breeding/hunts.
 

GroErr

Well-Known Member
Different experiments, similar results. Convincing
Yeah saw your post, similar end results. That was when I first switched to COBs and had 600w in a 3.5 x 9' for a couple of rounds (I've added another 200w since). When I added some plants at the end of the room just because I had them available, I didn't have much light and spread out what I had to just barely cover those. While they ended up taking a long time, they did produce quite well.

This was a small 2gal plant, took 73 days vs. typically 58-62. Buds were much fatter than usual and all around not just the main.

BlueRipper-F2-P3-Day73-Harvest-COBs-1.JPG BlueRipper-F2-P3-Day73-Harvest-COBs-3.JPG
 

GroErr

Well-Known Member
Do you remember the yields? Was the g/week ratio higher than usual?
Beautiful girls, btw
No I don't bother weighing unless I'm experimenting on purpose but that was a clone that I ran for a couple of years for breeding so I had lots of previous reference and she was much fatter than previous runs. In this case it was just an accident that I noticed towards the end of the run when I happened to be running low wattage on one end of the room. It's interesting the many variances you run across in slightly different environments, in this case even in the same room but lower lighting conditions on one end. I've read that low lighting conditions can increase yields, may do that on purpose sometime to see if it's consistent but that run was awesome, just took forever.

Thanks, she was a beauty F2 that eventually produced some awesome offspring and mothered the BX1 crosses.
 

Old ninja

Active Member
13/11 + far red... 11 weeks , good production, some male flowers appear at the end..
10/14 + far red... 8 weeks, good production (I added more light to mantain DLI to keep production rates)
For sativa strains I think 10/14 plus far red is better. for quick fowering indica strains I prefer 13/11
Was there any difference in plant height? I have to keep my ladies short.
 

GroErr

Well-Known Member
Where have you read that?
Several posts on forums but haven't found anything solid like a paper/study. After seeing what I got out of that run it may be worth a test though. I'll have to wait until I get through some seed runs. Only way to really tell is using known clones for a baseline, then running them in same size containers, and flipping them at the same size.
 
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