21/13 23/13 light cycles?

ah, so possibly the 175-180nm would not affect this though and stimulate THC. daytime would seemingly be optimal though.

i don't understand though, if red converts Pr to Pfr and Pfr turns to Pr overnight, would an far red diode only turned on for the duration of the night, help (if far red helps Pfr turn to Pr)?

It should (at least in a scientific setup) even suffice to use it for a few minutes directly after lights out to turn all the Prf into Pr. Thereby, the perceived night is as long as the 'apparent/real' night whereas under normal conditions, the perceived one is shorter by 1-4 hours depending on the plant species.

Only Ornamental said:

That whole far red light thing is simply fascinating.

Click to expand...

Probably another reason why some sativa's start flowering here (the kop van Noord Holland ) with less than 8 hours of night.

"During the night, the PFR converts back to PR.
The PR form is needed for the release of the flowering signal.
You need X hours of darkness in which to convert all the PFR present at sundown into PR and carry out the supplementary reactions leading to the release of the flowering signal ("florigen").

If this process is interrupted by a flash of 660-nm light, the PR is immediately reconverted to PFR and the night's work is undone (C)
A subsequent exposure to far-red (730 nm) light converts the pigment back to PR and the steps leading to the release of "florigen" can be completed (D)
Exposure to intense far-red light at the beginning of the night sets the clock ahead about 2 hours or so by eliminating the need for the spontaneous conversion of PFR to PR (E)."



That's why HPS does so much better as you would expect based on theory, it releases a large amount of FR after it is switched off.
If you have led just add an incandescant which you switch on 20 minutes before lights go out and leave on for half an hour.
It will make a huge difference.

I did five harvests with a half hour of far red immediately after lights out. These were done at 12/12 to establish a baseline.
The strain is a sativa that normally produces seeds starting at six weeks, it smokes so well that early harvests worked out and the plant is productive.
While establishing the baseline it was noted that the sativa no longer produced seeds at the six week mark. In fact taking the plant all the way to thirteen weeks did not produce any seeds.
Five harvests were done to confirm what happened was not an anomaly.

Now the shorter nights are being tested. The plant is going into it's second week of 14/10.
It will be another five harvests before anything definitive can be said but so far so good.

Phaeton said:

I did five harvests with a half hour of far red immediately after lights out. These were done at 12/12 to establish a baseline.
The strain is a sativa that normally produces seeds starting at six weeks, it smokes so well that early harvests worked out and the plant is productive.
While establishing the baseline it was noted that the sativa no longer produced seeds at the six week mark. In fact taking the plant all the way to thirteen weeks did not produce any seeds.
Five harvests were done to confirm what happened was not an anomaly.

Now the shorter nights are being tested. The plant is going into it's second week of 14/10.
It will be another five harvests before anything definitive can be said but so far so good.

Click to expand...

to clarify, the sativa normally seeds in 6weeks 12/12? and far red, 730nm for 30min of dark period prevented this?

i originally was puzzled and thought maybe you meant the baseline was 12/12 no far red and no seeds formed, then 12/12 with far red got 6week seeds.

it's hard to tell because "normaly" could mean; the sativa was not grown previously and the 1st 5 were "normaly" after 5 times using far red and some later baseline test at 12/12.

it is confusing to me because if i interpret it in the case that normal means, without far red, then it implies far red prevents seeding. with it being tested again with even less light, i could assume you meant it did work; unless, it was to prove far red is equally or more preventative to seeding than less light at 14/10.

i also am uncertain if you mean to say that seeding and flowering are affected differently in male and female plants, by far red light.

please write the details

Phaeton said:

Now the shorter nights are being tested. The plant is going into it's second week of 14/10.
It will be another five harvests before anything definitive can be said but so far so good.

Click to expand...

This is after 19 days 14/10:



It works if you use far red, but the downside is it will take a few weeks longer to finish.
The same goes by the way for longer than 24h light cycles, while shorter schedules have the opposite effect.

Some sativa's will even start to flower with less than 8 hours dark if it gets darker relatively fast = 3.5 minutes per day.
They are much more sensitive to this change than indica's, at our latitude after solstice they are auto flowers avant la lettre.

i am still somewhat confused. please copy/paste this with the findings. it will make it a whole lot easier to understand, remove the guesswork and show what we know, what we don't know and what we predict.

* 12/12....... far red (730nm) on during first (0) minutes of night.
(leave one, [observed] or [predicted]) __ weeks to flower

* 12/12....... far red (730nm) on during first (30) minutes of night.
(leave one, [observed] or [predicted]) __ weeks to flower

* 12/12....... far red (730nm) on during first (ALL) minutes of night.
(leave one, [observed] or [predicted]) __ weeks to flower

* 10/14....... far red (730nm) on during first (0) minutes of night.
(leave one, [observed] or [predicted]) __ weeks to flower

* 10/14....... far red (730nm) on during first (30) minutes of night.
(leave one, [observed] or [predicted]) __ weeks to flower

* 10/14....... far red (730nm) on during first (ALL) minutes of night.
(leave one, [observed] or [predicted]) __ weeks to flower

here's a repost with color highlights to help visibility. i imagine the form above is better for a poster to edit, while this one is easier on the eyes.


* 12/12....... far red (730nm) on during first (0) minutes of night.
(leave one, [observed] or [predicted]) __ weeks to flower

* 12/12....... far red (730nm) on during first (30) minutes of night.
(leave one, [observed] or [predicted]) __ weeks to flower

* 12/12....... far red (730nm) on during first (ALL) minutes of night.
(leave one, [observed] or [predicted]) __ weeks to flower

* 10/14....... far red (730nm) on during first (0) minutes of night.
(leave one, [observed] or [predicted]) __ weeks to flower

* 10/14....... far red (730nm) on during first (30) minutes of night.
(leave one, [observed] or [predicted]) __ weeks to flower

* 10/14....... far red (730nm) on during first (ALL) minutes of night.
(leave one, [observed] or [predicted]) __ weeks to flower