Thegreengrower64
Well-known member
Sorry pal, but in every single vid I've seen of Joe pietri he clearly says loud and clear that cannabis is a short day plant like crysanthamons, and not a long day (18hrs).
Done plenty research pal.
-
ICMag with help from Landrace Warden and The Vault is running a NEW contest in November! You can check it here. Prizes are seeds & forum premium access. Come join in!
LED and BUD QUALITY
- Thread starter Tropical Sun
- Start date
Done plenty research pal.
You must of had a different White Rhino to the legendary clone ? , White Rhino was very potent ( Indica like) , defo not weak at all ? , and very pungent and Skunky ( euro Skunk more like Cheese).
The White clone I had from USA was like you described, looked amazing but defo was no knockout like the White Rhino.
Also the White widow from
Late 90's was very potent also.
As with everything Original White Widow clone and White Rhino was lost in Holland and replaced by some shwag version.
Ca++
Well-known member
Then he is clearly wrong. The cannabis plant is neither.
Listen to Greyfader. He has not used either term where you have quoted him. He gets it, does it, and sets a shining example.
@Thegreengrower64
You seem to be confusing light intensity and day/night length.
@greyfader talks about DLI (Daily Light Integral), which is a relationship between them - to reduce day length without sacrificing yield, you must increase light intensity in order to maintain DLI.
For example if you were flowering with -1000PPFD over 12 hours and you wanted to reduce day length to 8 hours, you would need to increase PPFD to -1500 to maintain DLI and yield.
You might look to do this to take advantage of off-peak electricity costs, for example.
You seem to be confusing light intensity and day/night length.
@greyfader talks about DLI (Daily Light Integral), which is a relationship between them - to reduce day length without sacrificing yield, you must increase light intensity in order to maintain DLI.
For example if you were flowering with -1000PPFD over 12 hours and you wanted to reduce day length to 8 hours, you would need to increase PPFD to -1500 to maintain DLI and yield.
You might look to do this to take advantage of off-peak electricity costs, for example.
Last edited:
Rocket Soul
Well-known member
Also, flowering under lower than 12 hours will generally shorten your flower cycle.
However youre not guaranteed same yield for same dli over less hours, theres somewhat diminishing returns on higher light intensity although people seem to differ in how much.
Another thing ive seen quoted online is that some genetics is only expressed with shorter days, not sure as its just forum talk.
greyfader
Well-known member
i used 8 on 16 off so as to not mess with the circadian rhythm. i used 1200 umols ppfd to deliver a DLI of about 35 mols per period. i have thought about using 8 on 12 off, which i think would work, but it doesn't fit into a human's schedule very well.
in this current grow i'm using the same strain but on the normal 12/12 schedule using 1200-1500 umols ppfd depending on where i measure on the plant, just to compare yield.
in one of Bugbee's videos, he shows a yield increase above 1200 umols but diminishing returns per unit of energy.
i don't think it matters all that much to a hobbyist but it could be an important consideration in a large facility.
in this current grow i'm using the same strain but on the normal 12/12 schedule using 1200-1500 umols ppfd depending on where i measure on the plant, just to compare yield.
in one of Bugbee's videos, he shows a yield increase above 1200 umols but diminishing returns per unit of energy.
i don't think it matters all that much to a hobbyist but it could be an important consideration in a large facility.
ChemDogLover
Active member
Ghost train haze grown under a DIY 800w led bar.
Ca++
Well-known member
Piecing bits together over the years, it seems you can get nights down to 10 hours, and days up to 16, Although these are separate reports. As you push the envelope, you start to stray too far from a 24 hour day. I really like the idea of shortening that 24 hours. Shorter nights and days, with the same photon capture through increased illumination. I don't really see any other goal I would want from changing times. However such talk is really quite mute. While no paper seems to directly address trying, I feel sure people have done so. A friend had a timer made decades ago, to try just this. So somebody has, surely.
greyfader
Well-known member
here is an interesting study on the effects of some different photoperiods.
www.ncbi.nlm.nih.gov
Moving Away from 12:12; the Effect of Different Photoperiods on Biomass Yield and Cannabinoids in Medicinal Cannabis - PMC
The standard practice to initiate flowering in medicinal cannabis involves reducing the photoperiod from a long-day period to an equal duration cycle of 12 h light (12L)/12 h dark (12D). This method reflects the short-day flowering dependence of ...
www.ncbi.nlm.nih.gov
to quote the abovementioned study, which I'm sure reflects the observations of most cannagraphers in here:
"Although cannabis is unequivocally considered a short-day flowering plant, the evidence from these studies show that flowering is frequently initiated in a photoperiod in excess of 12 h, i.e., a slightly longer day than night. The differences in hemp flowering time have been linked to their origin with cultivars adapted to more northern climates (in the northern hemisphere), showing reduced photoperiod sensitivity (and thus earlier flowering) than southern adapted cultivars grown under the same photoperiod [18]. These previous observations support the question as to whether the blanket rule of 12:12, applied by commercial glasshouse/indoor growers, is actually optimal for maximum yields for all cultivars."
"Although cannabis is unequivocally considered a short-day flowering plant, the evidence from these studies show that flowering is frequently initiated in a photoperiod in excess of 12 h, i.e., a slightly longer day than night. The differences in hemp flowering time have been linked to their origin with cultivars adapted to more northern climates (in the northern hemisphere), showing reduced photoperiod sensitivity (and thus earlier flowering) than southern adapted cultivars grown under the same photoperiod [18]. These previous observations support the question as to whether the blanket rule of 12:12, applied by commercial glasshouse/indoor growers, is actually optimal for maximum yields for all cultivars."
Verdant Whisperer
Well-known member
This would explain why equatorial Sativas usually have low levels of CBD "14L:10D led to a significant increase in the CBD concentration, which led to a 50–100% increase in total CBD yield"here is an interesting study on the effects of some different photoperiods.
Moving Away from 12:12; the Effect of Different Photoperiods on Biomass Yield and Cannabinoids in Medicinal Cannabis - PMC
The standard practice to initiate flowering in medicinal cannabis involves reducing the photoperiod from a long-day period to an equal duration cycle of 12 h light (12L)/12 h dark (12D). This method reflects the short-day flowering dependence of ...
They want to start growing CBD hemp here in Central America with 12/12 lighting and keep it below 0.3% thc based on these measurements all the hemp strains that test lower than o.3% THC in climates with more light hours are going to be hot here in my opinion. so basically growing low thc and high cbd strains in 12/12 i see going to be hard to do. the thc levels will increase and cbd decrease the closer to the equator. so all these well known help strains grown in oregon, and usa, will not have same cbd,thc ratio grown here in 12/12 based on that study.
Last edited:
Ca++
Well-known member
They forgot to say, that NL and HK have gone through decades of selection, done under 12/12 conditions. Finding plants at their peak, in those conditions. Making it unlikely these highly selected lines, would actually be better tuned to some other day length.
I have had to lengthen my days by half hour, since going LED. They were racing to the finish.
I have had to lengthen my days by half hour, since going LED. They were racing to the finish.
Rocket Soul
Well-known member
Torontoke on riu has threads on low daylight hours, think he went all the way down to 9.
greyfader
Well-known member
i ran 8 hours of intense light for maybe 6-7 grows and got good results. but were they the best results? i don't really know yet but this round i'm running one of the same strains for 12 hours at high intensity. 50-60 mols per period.
i have photos of the previous run with this strain to compare so in about 4-5 weeks i'll have a visual comparison at least.
i have photos of the previous run with this strain to compare so in about 4-5 weeks i'll have a visual comparison at least.
