What is the least amount of dark hours to keep 99% of plants in flower?

[imadoofus]

only when a theory is expanded through the method does it become scientific theory. i dont recall claiming otherwise, only that all scientific theories are borne OF THEORY/HYPOTHESIS

maybe, i should put the bong down ; )

no offense taken, SPUR i attempted to convey a jovial atmosphere by commending your banana... as long as you keep it in the fruit basket, yellow and unpeeled.

 

[Thomkal Vwalaa]

as long as you keep it in the fruit basket, yellow and unpeeled.

lol, what happened here? pick up the bong and smoke bubble hash, but make sure the water is clean. and please keep the banana in your pants.

From DJ:
"I would like to mention a little warning concerning the lure of science. Science is a wonderful thing, especially in its pure analytical sense. But science is limited in it's scope by strict boundaries. ... remember to use science as a tool and not be used by it."

spurr, we all love you, your humor is lost in your tone, no worries mate. let's get back to the dark cycle.

From mr Short's book:
"Indica and Sativa varieties differ in their photo or photo-reactive rate. The 18-6 - 12/12 flower cycles are primarily beneficial to the Indica varieties..."

Then later:
"Beter Phenotypes through Enviroment
After many years of firsthand experience breeding herb, I believe that the two most influentialo environmental triggers for phenotypic variation and expression among current indoor herb breeding projects are:
1 - Photoperiod
2- Angle of light
Specifically, I find the single most powerful influence to the indica-domiant phenotype is the 18/6 veggie cycle and 12/12 flowering cycle. The 18/6 veggie and 12/12 flower cycle is an attempt (however poor) to mimic the Inidica producing outdoor environment (photo-period). It is my belief that this light timing cycle strongly influences the indica phenotypic expression. Photo periods at the equator would be closer to a 13/11 veggie and 11/13 flower cycle.

The exact photo-period formula that I incorporate into my growing/breeding regime will remain a trade secret, but my advice is to experiment with different photo periods, keep good notes and pay attention. Avoid the 18/6 - 12/12 phtoperoids while tweaking the times in half-hour increments or less with each breeding cycle until more desirable results in the finished product and the next generation of offspring are noted"

Well Mr. Short, ever since I bought your book and read this section, I've changed my opinion on you personally. Why call this book "an expert breeder shares his secrets" if you don't actually share the secrets?

 

[spurr]

Yea, I thought the banana joke from imadoofus was funny too.


FWIW, I wouldn't take DJ's advise on issues of growing from what I have read of his writings. Anyone who thinks "angle of light" has anything to do with flowering is highly suspect in their understanding, along with anyone who writes "veggie" in a book...

I could go on about him but it's too far off topic to this thread; such as his apparent confusion of phenotype and genotype. E.g. "indica-dominant" isn't factor controlled by phenotype, a plant doesn't 'become' indica due to daylength (nor due to spectrum of light). I have seen other growers make that same very flawed claim, like C-ray from CW2.

It's funny DJ thinks the daylength he uses is a trade secret.

 

[Thomkal Vwalaa]

Yea, I thought the banana joke from imadoofus was funny too.


FWIW, I wouldn't take DJ's advise on issues of growing from what I have read of his writings. Anyone who thinks "angle of light" has anything to do with flowering is highly suspect in their understanding, along with anyone who writes "veggie" in a book...

I could go on about him but it's too far off topic to this thread; such as his apparent confusion of phenotype and genotype. E.g. "indica-dominant" isn't a phenotype, a plant doesn't 'become' indica due to daylength (nor due to spectrum of light); I have seen other growers make that same very flawed claim, like C-ray from CW2.

It's funny DJ thinks the daylength he uses is a trade secret.

and that makes this thread (and sub-forum) so important as there is, as you point out, tons of BS coming the form of print, especially for sale cannabis specific literature. the issue is the thread title: "What is the least amount of dark hours to keep 99% of plants in flower?" can't be answered without talking about specific genotype (correct me if I should have just said genetics or ?).

To claim X/Y hours dark/light will keep flowering can only be accurate for the exact genotype studied. Do we need to approach this question by variety and genotype, leaving the auto flowers out?

ie
What is the least amount of dark hours to keep Afgani in flower?
What is the least amount of dark hours to keep Trainwreck in flower? and so on.

 

[ShroomDr]

the phytochrome that controls flowing (i.e. Pfr) is known as "phytocrhome B", aka "phyB". Also, a reduction to critical level of Pfr is what is required for flowing to occur, not a increase in Pfr.

ref:

"The Contrasting Effects of Phytochromes A and B on Flowering"
A Companion to Plant Physiology, Fifth Edition
by Lincoln Taiz and Eduardo Zeiger
2010, Chap. 25. Topic 25.11
http://5e.plantphys.net/article.php?ch=t&id=250
​

Thanks for the correction. this was a nice tidbit

In LDPs .. phytochrome B (phyB) appears to be an inhibitor of flowering, since mutations in the gene PHYB that eliminate or reduce the amount of the phyB protein cause more rapid flowering

As far as theories go, lets not forget GRAVITY IS A THEORY.




-

 

[spurr]

@ all,

Here are some studies on cannabis and photoperiod for flowing (first two studies). Neat reading because they are old, one from 1953 and one from 1958; not much new info, but neat reading such old papers

I found the papers the MicrobeMan posted somewhere else in regard to non-photoperiodic flowering induction of equatorial ectoype trees/plants (due to little photoperiodic fluctuation near the equator). I uploaded the first one below and I will upload the second one tomorrow, I hope. One of the papers I uploaded on the last page also references non-photoperiodic induction of flowering (IIRC genetic).

The first paper had to be uploaded to a file host because it's too big to upload here, I uploaded it to Russian based file host that doesn't require JavaScript, etc. That is safter than US based file hose, IP wise.


1. "Photoperiodic Responses of Hemp"
H. A. Borthwick and N. J. Scully
Source: Botanical Gazette, Vol. 116, No. 1 (Sep., 1954), pp. 14-29

(passphrase is "ilovecanna" - without quotes)

• http://www.file-upload.net/download-3019540/burp.zip.html

2. "The Influence of Photoperiodicity on the Sexual Index in Hemp (Cannabis sativa L.)"
JAROSLAV LIMBERK
BIOLOGIA PLANTARUM (PRAHA), Vol. 1, No. 3, pp. 176-186 (1959)


3. "Photoperiodic induction of synchronous flowering near the Equator"
Rolf Borchert, Susanne S. Renner, Zoraida Calle, Diego Navarrete,
Alan Tye, Laurent Gautier, Rodolphe Spichiger & Patricio von Hildebrand
NATURE, VOL 433, 10 FEBRUARY 2005

 

[El Toker]

I've already mentioned elsewhere that I have grown using a 5 day week light cycle and it worked well and probably (best guess) improved yield.

Attempts to initiate flowering using this light cycle with a couple of strains were unsucessful. However, for all the strains that I've tried once flowering had started under 12/12 I was able to successfully maintain flowering 21hr36min on and 12 off.

For anyone who's interested the exact timings, that I got of overgrow years ago are.

Day 1 – Monday 15:36 - Tuesday 13:12
Day 2 - Wednesday 01:12 – Wednesday 22:48
Day 3 - Thursday 10:48 - Friday 08:24
Day 4 – Friday 20:24 - Saturday 18:00
Day 5 – Sunday 06:00 - Monday 03:36

the big disadvantages to this that I found were:

- It completely disrupts your daily routine and if you're going out working it can mean a couple of days between being able to check on your grow.

- It gets to be a pain during the height of summer. Normally I would have lights off during the day and on at night to help with temp control.

 

[spurr]

.

 

[Aeroguerilla]

ive been running 11.25hours on 12.45 hour off

forces into flowering reducing time in the end

 

[Cannabologist]

Thomkal Vwalaa
and that makes this thread (and sub-forum) so important as there is, as you point out, tons of BS coming the form of print, especially for sale cannabis specific literature.

- I concur with this assessment. Most horticulture literature aimed at Cannabis growers, as well as culture magazines like High times, skunk, cannabis culture, ect., are filled with baseless claims, incorrect information, and outright lies.

- this “BS” as you say, also expands to the internet on websites where old and new misinformation alike is created and spread.

-the “BS” is not limited to layperson’s media, but scientific literature as well is riddled with poor and biased study regarding cannabis, especially concerning the “drug abuse model”

Spurr:
Here are some studies on cannabis and photoperiod for flowing (first two studies). Neat reading because they are old, one from 1953 and one from 1958

I was going to upload these from my library as I had time...

Spurr, I believe these would be of interest as well https://www.icmag.com/ic/showthread.php?t=198130; Borthwick and Skully did a review of “Schanffner”. It is interesting to note that “Schanffner” at the time had an ongoing rivalry with “H.C McPhee”, her papers follow Schanffner in content. They are quite old, and I believe “Schanffner” is the first to discover how to create all feminized Cannabis seed via mere alteration of the photoperiod, but I will have to check Pritchard, F. J. Change of sex in hemp. Jour. Hered. 7:325-329. 1916.

 

[shawkmon]

i say 14.5/ 9.5dark, work yer way back from there,

Clones + cfls + cheapo timers = win

 

[spurr]

@ Shroom,

FWIW, I recently came upon good methodology for defining critical nightlength for plants. I was reading a few studies on indoor growth of poppies and the issue of critical daylength and critical nightlength was discussed. While poppies are the opposite of cannabis, and need short hours of darkness to flower (i.e. > ~14 hr of light per day), the studies provide easy to follow methods to find critical nightlength with a high degree of accuracy (via two separate testing methods for correlation).

I plan to copy their work with cannabis in the near future, to better quantify critical nightlength for various ecotypes (races or species, ex., so-called sativa and indica) and cultivars. Once critical nightlength is quantified, I will work on minimal nightlength and maximal daylength in terms of dark respiration, photosynthesis [Pn] (re the point of photosystem(s) light saturation and reduction in Pn at various irradiances/daily light integrals and environ variables, ex., "midday depression of photosynthesis"), etc.

Once critical nightlength and critical daylength are better quantified we could use shorter or longer whole days (daylength + nightlength) and reduce (or increase) the time period until harvest, while increasing yield and growth (via. longer daylengths than 12 hours in flowering). Ex. for veg: if minimal nightlength is 4 hours and maximal daylength is 18 hours, the whole day would be 22 hours, not 24 hours. Likewise for flowering: if critical nigthlength is 10 hours and maximal daylength is 18 hours, the whole day would be 28 hours, not 24 hours.

I have been testing the Sentential 'Master Digital Timer' (MDT) for whole days shorter and longer than 24 hours with the repeat cycle timer feature. The MDT is the only inexpensive repeat cycle timer I have found that (a) offers very long 'on' and 'off' times (second/minutes/hours); (b) offers sufficient (albeit just barley) power to run HIDs (re max amps); and (c) has a built in breaker, high temp shutoff and restart, as well as time-delayed restart and other features. There are much better options, but the price goes up by a few hundred dollars ... I wish I was an electrical engineer, I could simply design my own for cheap and make it better suited to our needs!

 

[CoCo_Crazy]

I had some potted coco plants outside while i was building a new grow room. It wasnt 12/12 yet so i thought they wouldnt flower.....WOOPS

They flowered like mad starting 4 weeks before it was even 12/12 outside. What a fuckup, i had to reveg all the plants, then get them big enough to flower and then put them back into flowering, hellish waste of time.

 

[ShroomDr]

This thread/question is mainly to illustrate a point for vertical growers.

Plants need light to grow, so turning off the light to do work inside the environment is less than optimal. You can do your work directly after 'lights out' or up to two hours before the lights come on, as long as there is a 10 hour uninterrupted dark period.

Or at least this has been my experience with 2 clone only cuttings, and 10-15 seed strains.

 

[ShroomDr]

@ spurr, Are you trying to grow poppies indoors? Poppies dont like to be rained on, so i guess that might be a a good reason, but poppies can be grown outside.

IIRC poppy drug cultivars are visually identical to 'garden' cultivars. The only think that would give it away is lancing teh pods.

I read somewhere that the poppy seeds you can buy in the grocery were 'drug cultivar' (something about a tight control of poppy fields in NZ [by big pharma], and an overabundance of seeds). I was unable to germinate any when i tried 2-3 years ago, and i have no idea of the validity of this anecdote.

 

[spurr]

@ spurr, Are you trying to grow poppies indoors? Poppies dont like to be rained on, so i guess that might be a a good reason, but poppies can be grown outside.

Yes, for reasons such as temp in summer (they do best ~75'F day temp) and for breeding and experimentation. Poppies do like to get rain, however, near harvest time (pods upturning) rain and irrigation can/does leach some of the alkaloids we want, like morphine. That is why it's suggested to not water them heavily during the last two weeks before harvest.

IIRC poppy drug cultivars are visually identical to 'garden' cultivars. The only think that would give it away is lancing teh pods.

Yes, and in many states it's not illegal to grow them as ornamental only; it's harvest and use that gets one in trouble. I do plan to milk the pods at least twice, but I also am going to do extraction for very pure opium of the pods, incl. the stem up to 12" from pods and using the latex I milk (a' la "cooked flake opium", but much better process and extraction and purity).

Tips: Adding Na to fertigation for poppies not only helps them grow, but increases the morphine content. Spraying with traicontanol and GA3 has been found to increase morphine content considerably, and yield (as well as number and size) of poppy pods.

I read somewhere that the poppy seeds you can buy in the grocery were 'drug cultivar' (something about a tight control of poppy fields in NZ [by big pharma], and an overabundance of seeds). I was unable to germinate any when i tried 2-3 years ago, and i have no idea of the validity of this anecdote.

Yes, they are, at least some brands (ex., McCormick is cultivar of Papaver somniferum from NZ); but often they are not able to be germinated. You can viable poppy seeds online. I have a stash a buddy sent me, he has been breeding this cultivar for over 20 years. He told me it's heritage includes a Chinese ecotype(race) and the cultivar produces the highest morphine (and other drug alkaloids) content of any cultivar; and has lots of pods per plant. I'm looking forward to starting them big time, I have grown a handful to cabbage stage, but not flowered them.

The studies I read are quite good, I wish cannabis studies where that good (re PPFD, Co2, temp, photoperiodism, etc., etc.). A neat point is you can 'fix' the flowering stage of poppies once they are older than 4 days (from seeds), ex., via. days longer than 14 hours (in a 24 hour day) for 20 days, then one can go back to lower hours per day (ex., 9 hours of light) until harvest (to save on electric bill and days to harvest).

 

[devilgoob]

lettin everyone know that 12hrs of a spike in electricity is information.

7 or 8 hours (lol) would just look like something different.

I really should just try 8/10.5 with a haze ha ahaha. This is exciting I have never thought about a whole entire day and night shortened! Hazes are weird too. So that could be good.

Light angle matters, I can see how as red does not interact with the atmosphere like blue. So between equatorial sativas and autoflowering ruderalis, you have two extremes of different flowering and the different factors due to environment also taking into consideration that everything is a hybrid then you would really want to talk land-race strains.

 

[OakyJoe]

Keep this up