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Best time to change light schedule?

ParanoidFarmer

ParanoidFarmer

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I have about 3 medium sized plants that have been in flower for various lengths of time now. As it's getting summer, it's getting a bit hotter in my grow area and i need to switch the cycle to a better time period when it is less hot in the house/attic/etc. What is the best way to accomplish this without making my plants hermi? I was thinking maybe change it by an hour a day or so till they are on the right schedule.
 
AlwaysLearning

AlwaysLearning

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*coughing out big hit o hash* Oh man I dont know about that. I think once the photochrome/cryptochrome chemicals are in place eventually reversing the light cycle will wreck them. I know DJ short talks about changing some sativa strains to 10/14 cycles, but that occurs in nature, whereas the drastic change of an hour difference in light and day does not. If you can some how get a A/C to your plants or just more overall airflow that could help. You could also try to change up the cycle with just one plant and see what happens but you may have more problems from changing the light cycle than from the heat issues. Maybe someone else here has done an experiment with this. Best of luck!
 
FreezerBoy

FreezerBoy

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One blip won't hurt your girls. A blip everyday will screw you. Cold turkey is the way to go.

If you're flowering pull the ON pin from the timer after lights on. Allow for the "normal" light cycle. Wait for 12 hours or more of night. Pick a new sunrise and reset the timer.

If you're not flowering, enter the room at will, reset the timer and you're done. I screwup the lights 2-3 times every grow. I don't mean to it's just ... life. As long as the screwups are few and spaced out, you're cool.
 
vancityj

vancityj

Member
Like FreezerBoy had suggested, just change the 12-hr cycle to a new start time; it shouldn't harm them at all doing that once while retaining the 12-hr 'on' time.
 
Maj.PotHead

Maj.PotHead

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i used to worry about the same untill i setup my grow as follows

my veg runs during the day yr round 6am-12am midnight
my flower runs at night yr round 6pm-6am
when my plants go into flower they get 1st day 24hr light they start day off in veg 6am end the day in flower 6am next day. never had any problems this method and my clones start to stack flowers 10-12 days into flower :)
 
C

CheifnBud2

I have one plant that i change its night cycle from 10-14 hours once in a while. it hasnt shown hermi or been stressed, and its covered in trichomes.
 
L

lysol

ambr0sia said:
Do you think this rule of thumb holds true even if you're planning a dramatic change, say inverting your ON time from 8p-8a to 8a-8p?
Click to expand...

If your on time was during 8p - 8a, he's saying leave your lights off during that time, as well as 8a- 8p, then pick your new sunrise, lets say 8am is the new sunrise so it stays dark for an additional 8p - 8a

so 36hrs of darkness in that case ( minimum would be 12hrs of darkness ).

If you ran your lights for 24hrs it still wouldnt be a huge deal as a one time thing but would definitely stress the plants in a minor way, allowing the dark period minimizes stress.
 
S

silent_lemon

ambr0sia said:
Do you think this rule of thumb holds true even if you're planning a dramatic change, say inverting your ON time from 8p-8a to 8a-8p?
Click to expand...
i dont think they would be phased; would just want consistency thereafter..
What about all those trees/plants/other vegetation that sits next to super bright lights, street lamps, pathway lights etc, their light schedule would appear to be permanently fubar and yet they seem to do alright - just where my head is oriented...

**interested in FB's take though!! :joint: :woohoo:
 
L

lysol

silent_lemon said:
i dont think they would be phased; would just want consistency thereafter..
What about all those trees/plants/other vegetation that sits next to super bright lights, street lamps, pathway lights etc, their light schedule would appear to be permanently fubar and yet they seem to do alright - just where my head is oriented...

**interested in FB's take though!! :joint: :woohoo:
Click to expand...

Are you saying you went and looked up what a hermie hibiscus plant does and then checked those plants for symtoms? Cannabis is also sensitive to the night length*, not day length like lots of plants. some plants are not photoperiod sensitive either

* ( I think.... its either one or the other, the point is not all plants are alike tho )
 
FreezerBoy

FreezerBoy

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ambr0sia said:
Do you think this rule of thumb holds true even if you're planning a dramatic change, say inverting your ON time from 8p-8a to 8a-8p?
Click to expand...

Always has for me. I've done the 180º switch on a number of occasions. NEVER adjust the clock one hour a day till you reach a new schedule. The chances of screwing up are stacked against you. It's the daily screw ups that freak out the plant.
 
Lazyman

Lazyman

Overkill is under-rated.
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Yeah, the long dark periods don't seem to hurt em, I usually turn the lights off for a couple days when I flip em to 12/12, then another couple days before the chop. Saves on power bills a bit too! I actually wanted to veg my girls a little longer, but had to flip em because of this stupid heat wave, can't have 6KW of lights running in a non-AC building when it's 94* outside, lol
 
Owl Mirror

Owl Mirror

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AlwaysLearning said:
*coughing out big hit o hash* Oh man I dont know about that. I think once the photochrome/cryptochrome chemicals are in place eventually reversing the light cycle will wreck them. I know DJ short talks about changing some sativa strains to 10/14 cycles, but that occurs in nature, whereas the drastic change of an hour difference in light and day does not. If you can some how get a A/C to your plants or just more overall airflow that could help. You could also try to change up the cycle with just one plant and see what happens but you may have more problems from changing the light cycle than from the heat issues. Maybe someone else here has done an experiment with this. Best of luck!
Click to expand...

How would your advice effect a plant if one was attempting to re-veg after either sexing or flowering ?
 
Owl Mirror

Owl Mirror

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FreezerBoy said:
Always has for me. I've done the 180º switch on a number of occasions. NEVER adjust the clock one hour a day till you reach a new schedule. The chances of screwing up are stacked against you. It's the daily screw ups that freak out the plant.
Click to expand...

Actually, I wish someone would market a timer that matched the natural order of reduced light lengths. Since we all wish to compress time, I think day one beginning on 13 hours of day light and throughout the next six weeks, time down to an 11/13 schedule would be extremely useful, especially for Sativa's.

That is a mere 3 minutes each day of decreasing light.
Perhaps a digital, programmable timer would be able to accomplish this?
 
Xero000

Xero000

Member
I'm not trying to flame but none of the responses I've read here so far seem to communicate a the fundamentals of photoperiodism.

What needs to be recognized is the actual biochemical mechanism that controls photoperiodism and how it works.

Phytochrome isn't a molecule that only appears in a the plant when it is in a flowering lightcycle. Phytochrome is *always* present. Sunlight converts phytochrome from one form P(r) to anther P(fr). During periods of darkness, P(fr) will naturally revert back to P(r).

The P(r) form of phytochrome is what triggers the flowering signal to short-day plants. Optimal rates will vary from plant to plant, species to species, but you simply need to ensure that the plant receives a continuous dark period of sufficient length to allow it's P(fr) to fully convert back to P(r).

If you can do it without gross mistakes - a gradual change in light schedule would be less stressful to the plant than an abrupt 180 or "cold turkey" switch. A 180 switch will still work - as long as you end the original cycle on a dark period and begin the new cycle on a dark period (as some have suggested) - but it will introduce more stress.

These are pretty hearty plants though, it's not the kind of stress that is going to harm them significantly or induce hermaphrodism from a single occurance.
 
S

silent_lemon

hey xero000 - when people mention jumpstarting the flower period by sitting plants in the dark for more than a day, are they making sure all the P(fr) has turned into P(r) to trick the plant into early flowering? regarding indoor
 
Xero000

Xero000

Member
Exactly by using an extended dark period you are ensuring that the plant has the maximum level of P(r) to to send the metabolic signals for flowering.
 
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