Flowering with 14 hours light

BobCajun

BobCajun

Well-Known Member
Here's something I found interesting, from this article. It appears that weed can flower under surprisingly long days. The flowering phases were identical with 12/12 and the natural outdoor day lengths which varied from more than 14 to less than 12. This may explain why people have flowered with 14 hour days while using end of day far red treatments. I couldn't find any evidence that such treatments are capable of reducing the number of dark hours required for short day plants to flower, though it was useful for increasing stem length.

It's probably possible to flower with 14 hour days even without any far red treatments and the length of time to maturity may not be that much different from 12/12. Can't really tell from this table because at the end the days are less than 12 hours anyway, but I think it's possible. At least they started flowering and kept flowering at the same rate as 12 hours in the early phases, which is unexpected. Since the table shows that florets formed with 14.16 hours, they must have started being induced a week earlier with 14.4 hours. That particular strain, G5, was a high CBD strain, but it may be similar for THC ones.

 
BobCajun

BobCajun

Well-Known Member
whitebb2727 said:
I do this. I don't go straight to 12/12. I reduce gradually. Most strains will start flower at about 14-14.5 hours light outdoors and indoor if gradual decrease in time.
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Yeah it looks like 14.5 hours is the critical day length, at least for most non-equatorial strains. And notice that there was "rapid formation of new florets " until it got down to 12.56 hours, so might as well say 13 hours. Then at 12 1/2 hours it slowed and at 12 hours it ceased. Maybe we don't want rapid formation to slow or cease.

Maybe we need at least 13 1/2 hours to keep rapid formation going and then after say 8 weeks we would go down to 12 hours to induce senescence. But the only people who ever tried indoor growing with 14 hours are those who were under the impression that EOD far red was making 14 look like 12 to the plants. That impression was almost certainly false. I guess we'd have to ask one of those people what the results of a 14 hour photoperiod were. The far red obviously doesn't equate to 2 more hours of darkness, because I tried it before using 12/12 and it still took 10 weeks to ripen. It would have ripened much faster if it worked, because it would have been like 12/14.
 
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BobCajun

BobCajun

Well-Known Member
Interesting post from another forum;
"So I know a guy that's been growing indoor and outdoor since about 97 and he was telling me that the past few grows he's been doing 24/0 veg and 14/10 flower. He says the buds are way bigger and much denser and the yield is almost doubled. He said when doing 18/6 and 12/12 he would get a little more than 1.5 lbs per 1000w. He says with this method he's pulling almost 3 lbs per 1000w. Anybody else ever hear anything on this before?" source
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Must say, twice the yield does sound appealing. I think I'll stick with 13 though. Kind of a compromise.
 
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Eagle-ize

Eagle-ize

Member
In my experiences playing with longer photoperiods in the reproductive (flowering) phase, the longer hours produced a bit more weight with slightly larger buds but it didn't double my yield. They did, however, seem to finish a bit sooner than the plants on the 12/12 schedule. At the time, I had already made the transition to LED so...

A1000w HID radiates IR light for a short period after it is turned off so maybe we can speculate that there is some correlation there.
There are many studies on EOD IR exposure for plants, however, I have found nothing substantial related to cannabis.

I believe the key to the yield directly related to the amount of total light the plant gets (daily light integral). If IR is stated to have
photomorphogenic influence to promote flowering responses, it may be exactly what the plant needs to counteract the longer photoperiod.
After all, it is what occurs in nature.

Nice find sir! This topic is interesting to me so please share your thoughts.

Cheers!
 
J

JDMase

Well-Known Member
a senile fungus said:
The longest duration of light during flower I've ever done is 14hrs. A couple of my strains started to reveg under 14hrs, so I went back to 12/12 to keep it simple.
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Maybe with 14 hours you definitely need the far red? Or failing that 13.5 or 13 hours would still be benefitial when compared to 12/12 in some instances?
 
a senile fungus

a senile fungus

Well-Known Member
I didn't notice any significant faster finishing time or growth rates, but a couple of those strains were new to me.

And I don't necessarily think longer days are that beneficial, this is a long night plant. I've found that shortening my veg daylight times (from 20/4 now I'm at 16/8) seems to have a more significant impact on flower onset than longer flowering days. Just my experiences...
 
boilingoil

boilingoil

Well-Known Member
Just from my experience in outdoor growing my plants tend to start flowering around the first week of August at my latitude ( 39.7 degrees) about the same time as my sunrise to sunset time hits the 14 hour mark.
I start my flowering at 14/10 and cut a half-hour every week till 12/12. Never saw a increase with flowering times over a straight 12/12 regime and the extra lighting cost over a regular cycle is around $5 more running 600 watts and i'm pulling close to 2 units from a 4x4 with said 600 watts.
 
J

JDMase

Well-Known Member
boilingoil said:
Just from my experience in outdoor growing my plants tend to start flowering around the first week of August at my latitude ( 39.7 degrees) about the same time as my sunrise to sunset time hits the 14 hour mark.
I start my flowering at 14/10 and cut a half-hour every week till 12/12. Never saw a increase with flowering times over a straight 12/12 regime and the extra lighting cost over a regular cycle is around $5 more running 600 watts and i'm pulling close to 2 units from a 4x4 with said 600 watts.
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I may have read that wrong but are you saying you flip from your veg (18/6 or whatever) to a 14/10, reducing to 12/12 and that costs you $5 (per week? In total?) and what was your benefit to doing so? Im confused haha
 
boilingoil

boilingoil

Well-Known Member
JDMase said:
I may have read that wrong but are you saying you flip from your veg (18/6 or whatever) to a 14/10, reducing to 12/12 and that costs you $5 (per week? In total?) and what was your benefit to doing so? Im confused haha
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Yes from 18/6 to 14/10, and that's for a whole flowering cycle cost of extra lighting. I pay less than $.10 a KWH.
I'm pulling almost 2 units from a 600 in a 4x4.
 
BobCajun

BobCajun

Well-Known Member
Eagle-ize said:
In my experiences playing with longer photoperiods in the reproductive (flowering) phase, the longer hours produced a bit more weight with slightly larger buds but it didn't double my yield. They did, however, seem to finish a bit sooner than the plants on the 12/12 schedule. At the time, I had already made the transition to LED so...

A1000w HID radiates IR light for a short period after it is turned off so maybe we can speculate that there is some correlation there.
There are many studies on EOD IR exposure for plants, however, I have found nothing substantial related to cannabis.

I believe the key to the yield directly related to the amount of total light the plant gets (daily light integral). If IR is stated to have
photomorphogenic influence to promote flowering responses, it may be exactly what the plant needs to counteract the longer photoperiod.
After all, it is what occurs in nature.

Nice find sir! This topic is interesting to me so please share your thoughts.

Cheers!
Click to expand...
What I'm using now is 13/11. It's been on that for the last week or so. Seems to be working well, a bit more growth than with 12/12. I'm not going to use 14 because I don't think the extra power would be worth it and it's bad enough dealing with the heat for 13. I'll see how this run turns out and report the results. Might drop it to 12/12 for the final week.

About the EOD far red, the main effect is stem elongation. I tried it with an incandescent blacklight under 12/12. The plants stretched like crazy with little branching, which is another effect of the far red, suppression of branching. What it does is mimic dense planting, like in a hemp field. If you've ever seen pics of a hemp field you probably wouldn't want plants like that.

You may be right about the HID putting out far red after it shuts off. MH not so much but HPS you can see the arc tube is red. That may explain why HPS grown plants are stretchy and MH grown ones aren't. It only takes about 1 watt of far red light per square meter to produce the effect so that red glow may very well be supplying it. Since it's only for a few seconds it may only cause a certain amount of extra stretch. Probably pure far red for say 15 minutes would make it a lot stretchier than an HPS.

BTW for those who do still use HPS, it might not be a bad idea to use a red light for 5 minutes after the HPS shuts off. That would counteract any far red from the arc tube glow and also from the actual on state during the full day. Again, it only requires a low wattage. A 13w red "party" CFL would probably do it, if you can't find red LEDs. In theory, you should get much stockier and branchier plants. But come to think of it, the arc tube probably puts out far red at first and as it cools it probably gets down into the red range, so it may already be EOD red. But it may not be long enough. You really need a good 5 minutes straight. Maybe that's why HPS produces kind of stretchy plants but not hemp type stretchy. It may have just enough EOD red from the glow to somewhat counter the far red but not fully.

I just found a page with the red/far red ratios of HPS and MH. Hps is 1.05 (to 1) and MH is 3.8. So that probably explains the plant height difference between them, more blue in the MH may also contribute to that. So it looks like HPS really could benefit from EOD red to counter that high far red content. People currently sell far red lights for EOD far red but nobody sells red lights for EOD red. They missed the boat on that one. You could call it the HPS far red neutralizer. MH style plant growth from HPS lights. It's magic.
 
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J

JDMase

Well-Known Member
BobCajun said:
What I'm using now is 13/11. It's been on that for the last week or so. Seems to be working well, a bit more growth than with 12/12. I'm not going to use 14 because I don't think the extra power would be worth it and it's bad enough dealing with the heat for 13. I'll see how this run turns out and report the results. Might drop it to 12/12 for the final week.

About the EOD far red, the main effect is stem elongation. I tried it with an incandescent blacklight under 12/12. The plants stretched like crazy with little branching, which is another effect of the far red, suppression of branching. What it does is mimic dense planting, like in a hemp field. If you've ever seen pics of a hemp field you probably wouldn't want plants like that.

You may be right about the HID putting out far red after it shuts off. MH not so much but HPS you can see the arc tube is red. That may explain why HPS grown plants are stretchy and MH grown ones aren't. It only takes about 1 watt of far red light per square meter to produce the effect so that red glow may very well be supplying it. Since it's only for a few seconds it may only cause a certain amount of extra stretch. Probably pure far red for say 15 minutes would make it a lot stretchier than an HPS.

BTW for those who do still use HPS, it might not be a bad idea to use a red light for 5 minutes after the HPS shuts off. That would counteract any far red from the arc tube glow and also from the actual on state during the full day. Again, it only requires a low wattage. A 13w red "party" CFL would probably do it, if you can't find red LEDs. In theory, you should get much stockier and branchier plants. But come to think of it, the arc tube probably puts out far red at first and as it cools it probably gets down into the red range, so it may already be EOD red. But it may not be long enough. You really need a good 5 minutes straight. Maybe that's why HPS produces kind of stretchy plants but not hemp type stretchy. It may have just enough EOD red from the glow to somewhat counter the far red but not fully.

I just found a page with the red/far red ratios of HPS and MH. Hps is 1.05 (to 1) and MH is 3.8. So that probably explains the plant height difference between them, more blue in the MH may also contribute to that. So it looks like HPS really could benefit from EOD red to counter that high far red content. People currently sell far red lights for EOD far red but nobody sells red lights for EOD red. They missed the boat on that one. You could call it the HPS far red neutralizer. MH style plant growth from HPS lights. It's magic.
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That was a really good read man, ive got some serious stretch going on with my HPS and they're just looking awful and was hoping to counter act it. Gonna look up some red CFL's now to see if I can improve them and help them get bushier.

I am just starting to finish the flowering on my older ones, using a 100w reptile bulb. Was planning on using that for 10 mins at the middle of their day, it has IR uva and uvb, don't suppose that might help too do you? 1w per square metre would be good too (as I have a 1sqm tent) seen some far red led lamps that are damn expensive though!

Just googled, IR IS far red, right? So I could run my reptile bulb during the day for 10-15 minutes for supposed added trichomes and also after lights out for say the same amount for reduced stretch and flower initiation? Have I got that right?
 
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BobCajun

BobCajun

Well-Known Member
JDMase said:
That was a really good read man, ive got some serious stretch going on with my HPS and they're just looking awful and was hoping to counter act it. Gonna look up some red CFL's now to see if I can improve them and help them get bushier.

I am just starting to finish the flowering on my older ones, using a 100w reptile bulb. Was planning on using that for 10 mins at the middle of their day, it has IR uva and uvb, don't suppose that might help too do you? 1w per square metre would be good too (as I have a 1sqm tent) seen some far red led lamps that are damn expensive though!

Just googled, IR IS far red, right? So I could run my reptile bulb during the day for 10-15 minutes for supposed added trichomes and also after lights out for say the same amount for reduced stretch and flower initiation? Have I got that right?
Click to expand...
No, you didn't understand what I wrote. Far red, which is not quite IR (which is invisible and produces heat when it hits something), CAUSES stretching. Red, meaning normal red colored light, counters the stretching effect of far red. BTW the far red that plants use, around 730 nm, is visible, just not as bright looking as normal red. Infrared (IR) comes after far red and you can't see it.

So to keep your plants from stretching you need to get a red CFL, usually the only ones in stores are 13w ones, and run it for 5-15 minutes after the HPS goes off.

The thing about 1 watt means 1 watt of actual light output, not 1 watt from the wall. You'd probably need about a 5w light minimum for a square meter but might as well make sure by using a 13w CFL or even 2 or more, whatever you think will cover the area nicely.

The reptile light is only good for UV and a little extra PAR (plant usable light), since they do put out some white light in addition to the UV. I can't see it working as a source of EOD red to reduce stretch though. Just get a separate red light, simple as that. And obviously don't use any far red lights at all. Their only use is to make plants stretchy.
 
J

JDMase

Well-Known Member
BobCajun said:
No, you didn't understand what I wrote. Far red, which is not quite IR (which is invisible and produces heat when it hits something), CAUSES stretching. Red, meaning normal red colored light, counters the stretching effect of far red. BTW the far red that plants use, around 730 nm, is visible, just not as bright looking as normal red. Infrared (IR) comes after far red and you can't see it.

So to keep your plants from stretching you need to get a red CFL, usually the only ones in stores are 13w ones, and run it for 5-15 minutes after the HPS goes off.

The thing about 1 watt means 1 watt of actual light output, not 1 watt from the wall. You'd probably need about a 5w light minimum for a square meter but might as well make sure by using a 13w CFL or even 2 or more, whatever you think will cover the area nicely.

The reptile light is only good for UV and a little extra PAR (plant usable light), since they do put out some white light in addition to the UV. I can't see it working as a source of EOD red to reduce stretch though. Just get a separate red light, simple as that. And obviously don't use any far red lights at all. Their only use is to make plants stretchy.
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Yeah I re read that, I did wonder why you said that as obviously im running HPS and have stretch haha!

So which lights are the ones that are flower initiators? I thought those were "far red"? I'll do some more research. But in the meantime..

I'll give the cfl a go, thanks so much for your patience and information! Im certainly learning a lot.
 
BobCajun

BobCajun

Well-Known Member
JDMase said:
Yeah I re read that, I did wonder why you said that as obviously im running HPS and have stretch haha!

So which lights are the ones that are flower initiators? I thought those were "far red"? I'll do some more research. But in the meantime..

I'll give the cfl a go, thanks so much for your patience and information! Im certainly learning a lot.
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Yeah the "flower initiators" are far red. I don't think they initiate flowers though, just make the plants stretchy. Notice that none of the manufacturers show actual experiments proving that they do what they claim.

Now if anyone reading this has HPS lights and a PAR meter, it would be nice to know what the spectrum of a shut off HPS really is. Maybe it's far red, maybe it's red, we don't know because nobody ever thought to check it with a PAR meter.
 
Eagle-ize

Eagle-ize

Member
BobCajun said:
Yeah the "flower initiators" are far red. I don't think they initiate flowers though, just make the plants stretchy. Notice that none of the manufacturers show actual experiments proving that they do what they claim.

Now if anyone reading this has HPS lights and a PAR meter, it would be nice to know what the spectrum of a shut off HPS really is. Maybe it's far red, maybe it's red, we don't know because nobody ever thought to check it with a PAR meter.
Click to expand...
The problem with this measurement is that the wavelength of light that we want to measure is outside of the PAR meter's sensitivity range and there fore limited.

An UPRTEK Spectroradiometer may be sensitive enough as I believe it dips into 800nm territory.

Maybe an actual experiment is called for.
 
BobCajun

BobCajun

Well-Known Member
Eagle-ize said:
The problem with this measurement is that the wavelength of light that we want to measure is outside of the PAR meter's sensitivity range and there fore limited.

An UPRTEK Spectroradiometer may be sensitive enough as I believe it dips into 800nm territory.

Maybe an actual experiment is called for.
Click to expand...
Yeah I thought of that later, that a PAR meter doesn't actually show the spectrum just how much light energy is produced in the PAR range, which usually stops at 700 NM.
 
Eagle-ize

Eagle-ize

Member
BobCajun said:
What I'm using now is 13/11. It's been on that for the last week or so. Seems to be working well, a bit more growth than with 12/12. I'm not going to use 14 because I don't think the extra power would be worth it and it's bad enough dealing with the heat for 13. I'll see how this run turns out and report the results. Might drop it to 12/12 for the final week.

About the EOD far red, the main effect is stem elongation. I tried it with an incandescent blacklight under 12/12. The plants stretched like crazy with little branching, which is another effect of the far red, suppression of branching. What it does is mimic dense planting, like in a hemp field. If you've ever seen pics of a hemp field you probably wouldn't want plants like that.

You may be right about the HID putting out far red after it shuts off. MH not so much but HPS you can see the arc tube is red. That may explain why HPS grown plants are stretchy and MH grown ones aren't. It only takes about 1 watt of far red light per square meter to produce the effect so that red glow may very well be supplying it. Since it's only for a few seconds it may only cause a certain amount of extra stretch. Probably pure far red for say 15 minutes would make it a lot stretchier than an HPS.

BTW for those who do still use HPS, it might not be a bad idea to use a red light for 5 minutes after the HPS shuts off. That would counteract any far red from the arc tube glow and also from the actual on state during the full day. Again, it only requires a low wattage. A 13w red "party" CFL would probably do it, if you can't find red LEDs. In theory, you should get much stockier and branchier plants. But come to think of it, the arc tube probably puts out far red at first and as it cools it probably gets down into the red range, so it may already be EOD red. But it may not be long enough. You really need a good 5 minutes straight. Maybe that's why HPS produces kind of stretchy plants but not hemp type stretchy. It may have just enough EOD red from the glow to somewhat counter the far red but not fully.

I just found a page with the red/far red ratios of HPS and MH. Hps is 1.05 (to 1) and MH is 3.8. So that probably explains the plant height difference between them, more blue in the MH may also contribute to that. So it looks like HPS really could benefit from EOD red to counter that high far red content. People currently sell far red lights for EOD far red but nobody sells red lights for EOD red. They missed the boat on that one. You could call it the HPS far red neutralizer. MH style plant growth from HPS lights. It's magic.
Click to expand...
I have read that blue light inhibits etiolation (stretching) and my experience with various light sources corroborate this. If the FR light promotes it, what do you think would happen if it is used only after the initial stretch?

Here is a picture of an experiment I performed with MH and HPS. The MH was on for the first 8hrs of 12/12 and the HPS was on for the latter half. There was a 4hr period where both were on at the same time. At the time, I was still fairly new to growing.
DSC_1323.JPG
 
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