Outdoor photoperiod manipulation

D

donkeyjunk

Active Member
g'day,
I have recently read a scientific paper on hormone response to phytochromic adjustment.
or in layman's terms changing light cycle from 18/6 to 12/12 to initiate flowering in photoperiod cannabis plants.
which is standard practice for indoor growers .
the thesis basically postulated that the same could be done for outdoor plants,
-( which we see in greenhouses that have an automatic 12 hour darkness period built into the roofs of the greenhouse, to allow for several harvests per year)
BUT
the authors stipulated that building a nursery and giving the 1 month old (and 40cm high) cannabis plants (using REGULAR seed) an un-interrupted 12 hours of darkness for 10 - 14 days could sex all the 1 month old plants, and then repot just the females into larger 200L pots in all day natural (summer) sunlight, thereby reverting the 6 week old and 0.5 meter tall ( and artificially sexed plants) back into the veg cycle.
HAS ANYONE done this and could speak to the results they experienced from the exercise?
CHEERS
DONKEYJUNK

PS. there was also another OUTDOOR light manipulation experiment that, allowed the farmer to keep the plants in the vegetative state for an extended period of time, (whereby by being able to increase yields exponentially), which also gave the farmer the ability to nominate when the plants flowered and were harvested.
COULD ANYONE tell me if they had used this technique either?!?!??
 
donkeyjunk said:
g'day,
I have recently read a scientific paper on hormone response to phytochromic adjustment.
or in layman's terms changing light cycle from 18/6 to 12/12 to initiate flowering in photoperiod cannabis plants.
which is standard practice for indoor growers .
the thesis basically postulated that the same could be done for outdoor plants,
-( which we see in greenhouses that have an automatic 12 hour darkness period built into the roofs of the greenhouse, to allow for several harvests per year)
BUT
the authors stipulated that building a nursery and giving the 1 month old (and 40cm high) cannabis plants (using REGULAR seed) an un-interrupted 12 hours of darkness for 10 - 14 days could sex all the 1 month old plants, and then repot just the females into larger 200L pots in all day natural (summer) sunlight, thereby reverting the 6 week old and 0.5 meter tall ( and artificially sexed plants) back into the veg cycle.
HAS ANYONE done this and could speak to the results they experienced from the exercise?
CHEERS
DONKEYJUNK

PS. there was also another OUTDOOR light manipulation experiment that, allowed the farmer to keep the plants in the vegetative state for an extended period of time, (whereby by being able to increase yields exponentially), which also gave the farmer the ability to nominate when the plants flowered and were harvested.
COULD ANYONE tell me if they had used this technique either?!?!??
Click to expand...
Good afternoon @donkeyjunk hope you are well my friend.
It's a common practice in sexing reg's.
They go into flower thereby showing male or female.
By putting into a veg light cycle the flowering cycle is terminated, but not without effecting her.
She will go a bit wonky at first throwing single blade leaves.
And sprouting branches sometimes double the average volume.
You end up with extra branches and a funky looking but quite healthy girl.
I've done it many times, they are called Monsters.

Your second question is more basic.
Keeping a lady in veg (less than 12 hr darkness) 23/0 or 18/6 let's her grow and develop without flowering.
People commonly keep a lady in veg if they want a better bigger harvest.
Plant and roots just keep growing.
Then when they are ready to initiate flowering they switch their timer to 12/12.
Giving 12 hr of darkness produces the hormone initiating the flowering period.
Same as in nature.
When the days get shorter at the end of summer they know it's time to produce flowers before winter comes.
Hope that helps with your questions.

Stay safe
Bill
 
greenjeans said:
This is along the lines of something I've wanted to fiddle around with. I'll be watching the replies!!! :thumb:
Click to expand...
Hey @greenjeans How are you doing my friend.
It's a fun experiment.
If you have a few clones put one into the flower room for a week.
Then back into veg beside the other clones.
And she will go loopy growing like crazy.
It's a good experiment for kicks.
I've herd people say it increases thc levels.
But I'd like to see some science on that.

Stay safe
Bill
 
If it's just to sex them after about a month you could always cut some clones and find out that way. You don't necessarily need to root them, just put them in a 12/12 cycle and see if they're female. They'll flower in a cup of water.
 
donkeyjunk said:
PS. there was also another OUTDOOR light manipulation experiment that, allowed the farmer to keep the plants in the vegetative state for an extended period of time, (whereby by being able to increase yields exponentially), which also gave the farmer the ability to nominate when the plants flowered and were harvested.
COULD ANYONE tell me if they had used this technique either?!?!??
Click to expand...
Not outdoors but I have kept plants in a vegetative stage for months. Sometimes it is deliberate because the plant is a 'mother' and I am taking cuttings to get roots and become clones.

Sometimes it is not deliberate such as when the flowering cabinet or tent were filled and I had no choice but to hold onto the plant and wait for an open spot.
 
cheers thanks guys, I appreciate you taking the time to reply, but if you could actually read the question properly beforehand that'd be nice. ( not taking the piss, but just possibly saving us all some time!).

-so this is a reply for GREENJEANS, as it seemed that you actually understood the question, so ill share with you where I'm at,( research ) at the moment.
PART 1- yes it does work
a/ I got x500 of 2L planter bags and filled them up with my special soil blend for commercial growing, then put 1 REGULAR seed ( that had been soaking in beneficials for 72 hours)
- I have x200 planter bags @ 200L in the main plot, all filled with the same special High speed growing medium
they are all irrigated by an automated solar set up with a weekly watering schedule (but all are empty at the moment)
b/ I'm on day 11, of giving them a manipulated 13 hour daily dark period. - I solved this problem by buying a cheap light- weight framed plastic green house on eBay , (which I then totally covered in the thickest panda film you can buy, and used my quantum meter to read the ppfd (which was zero)). I then lift the green house over the top of the seedlings at 7 pm and lift it off at 8am, -giving the plants the best part of the days sun.
c/ on day 9 , I noticed that the first small percentage had started throwing their sex ( 2 days ago), the girls I put to one side and the boys I remove.
d/ THEREFORE in (hopefully) a couple more days, ill have roughly 250 (2 foot tall) females to transplant into the big pots outside, - which are currently getting 13h 45min of sunlight, in the 2nd week of summer ,( and won't start getting a full 12 hours of dark until the equinox on the 23rd of march
e/- ??????? SO MY CONCERN is that in a couple more days that the girls will suddenly be getting an extra 2 hours and 45 minutes of sun per day ( flicking them back into veg)- NOT TO MENTION THE SHOCK OF THE TRANPLANT.........
whereby they might NOT re-veg but finish up the flower cycle, for a 6 week old and 45 cm tall girl.

this thought is keeping me up at night as I have spent a LOT of time and money with this years crop.
-AND IT ALL BOILS DOWN TO... as far as all my research has led me to believe the ratio of indica/ sativa in the genetic profile of my seed stock, will basically govern whether they grow a 10cm bud in 8 weeks, or I get 3-4 pound plant per pot next May.

SO I ASK AGAIN, can anybody steer me right, with any relevant relevant advice....
... for example I'm thinking that if I top the first 2 inter-nodal lengths whereby removing the ( admittedly very small ) female sex glands ( which will supposedly briefly stop the hormones the girls use for flowering AND giving them a dose of liquid organic nitrogen, with a high bio-availability factor /- so its easier to revert to veg as the main macro needed for veg is readily available.
OR// giving them a dose of biostimulants with a higher gibberellin or cytokinnen ratio than auxins, therefor changing the hormone profile of the plants...?

im sure there is a simple answer.
cheers
guys
 
Hey Donk - You must be in the Southern Hemisphere?? Some of what you are talking about goes over my head but last year I started some plants waaaay too early with the intention of growing outside, some in the ground some in moveable tubs, to be moved into the greenhouse when cold. They showed their sex pretty early but then revegged. They were experiments so they got moved way back in the bush to the Beaver dam to let them go natural.
This year I am going to wait much longer to sprout (I don't want them so damn big) but what I wanted to try was to give them 2 or three hours of extra light, either morning or night, and then when the time seems right - stop - and I'm hoping that it is not so much a 12/12 thing as it is a sudden drop in hours of light.
What I was thinking is that if they go from 16 or 17 hours of light to only 14 or so - will that start the flip. Or are the plants stuck on that 12 hour business?? Will they flower and mature earlier before the weather turns??
I figure it can't hurt to try - if it doesn't work I've just wasted some money on electricity.
 
greenJ, I'm not sure whether you are talking about indoor or outdoor when you are talking about about giving them extra light?
im going to assume you are talking about adding the couple extra hours inside BEFORE you put them outside?!!
so the answer to your question is NO, a jump from 17 to 14 doesn't matter.
so to boil it down as simple as can be;
- there are only 3 genus of cannabis
- genus 1 and 2 are photoperiod flowering plants and will start to flower as soon as the plants get 12 hours of uninterrupted darkness. as long as you stay above the 12 hour line they will remain in veg no matter the difference in total amount of day light hours ( you've probably heard of them , they're called Indica and Sativa.
-genus 3 doesn't need set amount of light or dark in the day to flower, they just flower as they grow, you probably haven't heard of it, its called ruderalis . although the young kids in America like to call it autoflowering, ( they make out like its magic or alien technology or something), instead of just being a land race plant from eastern block Europe .

ANYWAY, back to my question, which no one has had a stab at yet, but I read a research paper saying that if you did grow out side, and NOT in a greenhouse. AND you did want to keep your plants in veg to grow much larger yielding plants and not let them turn to flower on the equinox (23rd of march or 23rd of September) depending on which hemisphere you found yourself in, (( march for me as im in the southern hemisphere .
SOOOOOOOO, Apparently you can illuminate your cannabis plants with a simple light ( it doesn't have to be high ppfd) but it does have to contain the light spectrum wavelength of 480nM, which I think lands it in the far red spectrum, for couple of minutes each night, between the hours of 9pm and 3am, thereby breaking up that period of uninterrupted 12 hours of darkness and the beginning of flowering.
NOTE; I have not tried this method but am very excited to give it a go in a couple of months, as I can simply add this light ( apparently can be bought in 12V) into my solar irrigation system.
ALSO the fact that my mid winters are like everyone else's late spring, would help in making this a very viable method for me to use.
HAS ANYBODY USED THIS ONE BEFORE? ID LOVE TO PICK YOUR BRAIN
CHEERS
DJ
 
Hey Donk - I'm an outside grow but starting in a greenhouse and the moveable gals end in the greenhouse. I would prefer to keep them smaller than they want to grow. My outdoor, in the ground gals are under a glass cover that is about 8' and the others are in rolling laundry tubs that can be moved back into the greenhouse when the weather turns cold in the fall. I was really hoping to find something other than autos just to be able to get a better jump on winter.
Good luck with your quest!!! :thumb:
 
well you could always buy a qPCR tester, which will give you a quick accurate simple DNA test, which you can do with a tiny bit of tissue sample from a seedling as little as 7 days old. if it comes back with a XY chromosome its a boy and XX if its a girl.
there's also one that also tells you the potency of each seedling, which , would obviously let you isolate each of the phenotypes that are in whatever genetics you are working with.
although its a little out of my price range at the moment
 
donkeyjunk said:
ANYWAY, back to my question, which no one has had a stab at yet, but I read a research paper saying that if you did grow out side, and NOT in a greenhouse. AND you did want to keep your plants in veg to grow much larger yielding plants and not let them turn to flower on the equinox (23rd of march or 23rd of September) depending on which hemisphere you found yourself in, (( march for me as im in the southern hemisphere .
Click to expand...
Sorry to say that I do not grow in a greenhouse but I am growing indoors and I have grown outside.

In the last 5 years that I have been following message threads on this site I notice that by the middle of each August there are North American growers asking what is going on because their outdoor 'photo-period' plants are starting to flower even though the Equinox is not until the 22nd of September which is an astronomical date for astronomers. It has little to do with the actual amount of available sunlight. If the outdoor growers had to wait till after the first 3 weeks of September before flowering starts around the 22nd they would have about 4 to 5 weeks of flowering before their planned harvest at the end of October when the weather starts turning cold. Certainly nothing like the 8 to 9 weeks recommended by many seed breeders and experienced growers.

The same sort of thing happens in the spring when North American growers start putting the indoor plants outside when the weather and the ground starts to warm up. It is not long before they are posting messages about what to do because their plants have started flowering and it is mid to late April or early May, about 5 to 6 weeks after the Spring Equinox. It is even possible to track when the new threads will start as the warm weather moves across North America from the ocean warmed climates of the western US and Canada to the midwest and then to the Atlantic coasts to the east. More than one North American grower on this message board will remind the new outdoor growers that it is best to wait until mid or late May no matter what the sunrise & sunset charts indicate.

I have brought up that the grower cannot use the sunrise and sunset times published in the charts whether in an almanac or on-line as the "end-all be-all" determination of length of daylight as it relates to the start of flowering. Nor can these charts be relied on to determine when there is enough light to prevent flowering in the spring. Personal observation, along with trying to take properly exposed photographs at sunrise and sunset, tells me that during the first hour (approximately) after sunrise and the last hour before sunset (approximately) there is not enough light to induce a change in the flowering hormone levels in the 'photo-period' Cannabis plants.

The information on the actual amounts of sunlight early and late in the day is lower is recognized. There are articles on the levels available with some google style searches. Even the wikipedia has articles on the low light level at start and end of the day.

donkeyjunk said:
this thought is keeping me up at night as I have spent a LOT of time and money with this years crop.
Click to expand...
And now you will be tossing and turning even more. Out of idle curiousity I have thought about how to do this research on the actual amount of available light. How to measure the LUX level? Do we need to get a hand-held LUX meter or a 'free' (TANSTAAFL) cell-phone LUX meter? Is one good enough? If only one is gotten then is it accurate enough? Or, should a second one be picked up to verify against the first one? How do we take LUX readings outside? How many LUX readings to take each morning and each evening until a pattern emerges? The spacing of each morning and evening LUX reading? And, how to set the built in shutters in the greenhouse to compensate for the light levels?

I have just wonder about all this and ask myself these questions. I envy the greenhouses you and many other growers have but it is not something I will be able to get.
 
Breaking the dark period with artificial light to keep outdoor plants in veg isn't that uncommon, and there is a thread on here somewhere with pics of someone doing it out in his backyard. Not a scientific reference, but he did succeed in keeping some of his plants in veg. I think it is referred to as gaslighting?

When I first decided to grow outdoors I took plants that had been under 18/6 lights and moved them outdoors at the end of May. At this latitude that's just over 15 hours of light. They started to flower. The days were getting longer, so they stopped.
When we got to the end of July, they started to stretch, and early August they were building buds.
This year I got my first buds on two of my outdoor plants August 1st. The other two plants took another two weeks before buds started to appear. August first is 14:30 hours of daylight here.
I'm not sure what really triggers flowering in outdoor plants, but in my experience it's not 12 hours of dark.

Hope that helps.
 
Melville Hobbes said:
I'm not sure what really triggers flowering in outdoor plants, but in my experience it's not 12 hours of dark.
Click to expand...
There is not enough light at the beginning and the end for the plants to use for maintaining the hormones that cause leaf growth. Knock one hour off the sunrise and sunset charts and it starts to fall into place. At the beginning of August the charts indicate 14 hours of "day" as the word is used by astronomers (not 14 hours of useable sunlight). Remove one hour at sunrise and sunset and we have approx 12 hours of uninterrupted dark. Enough to start the plant producing the hormones that start flowering.
 
Melville Hobbes said:
When we got to the end of July, they started to stretch, and early August they were building buds.
Click to expand...
This what I have been wondering about!!!
Now, did they seem to finish any earlier - where they ready before the weather started to turn bad??
 
greenjeans said:
This what I have been wondering about!!!
Now, did they seem to finish any earlier - where they ready before the weather started to turn bad??
Click to expand...
Weather turned bad around the beginning of September this year. We had the second rainiest September on record. There were only a couple of truly good days for the entire month, and they were really humid as all the rain evaporated.
But yes, they were finished by the first few days of October, while the other two could've used another week or so when I took them down a week later. The first half of October was pretty wet too, and the temps were dropping pretty low overnight.
This was the first year I lost more than max 10% to mold.
 
Hey Mel - I'm lucky if they would finish up by Mid October around here - sounds like you got a couple of weeks early. I'm going to try to keep better records this spring. I wasn't going to grow this year but last year was so crappy I want to try and improve!!! :hmmmm: It also seems to me that sometimes they just look tired but not really turning much amber but still done in. I'm hoping that a younger, smaller plant has a better result.
 

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