Changing light cycle mid-way thru flower?

[Puscifer]

Hi everybody.
I'm currently 4 weeks into flowering an 8 week strain and my lights come on at 7 a.m, off at 7 p.m.
I just got a new job that will have me gone all day so I need to change my "on" time to 7 p.m~7 a.m. (the exact opposite that it is now).
How do you guys suggest I go about this? Do I leave the lights on past it's current off time (7 pm) until I hit my desired off time then shut them off OR do I leave the lights off when they go off at 7 pm and leave them off until my desired "on" time? One way leaves the lights on longer initially, the other way leaves them off longer initially.
Which way would you guys do it?
Thanks in advance,
~Pus~

 

[Mant00th]

I just had to do the same thing for temp control... I let the lights stay out longer and then turn them back on at the start of the new 12/12 time. This way they don't get wierded out by having a random long day in the middle of their flowering cycle

By the way... THIS IS MY FIRST POST HERE, YAY!

 

[Puscifer]

HaHa, that was my first post as well!
Yeah, I was leaning towards leaving them off longer. I figured that was the least stressful way.
Thanks for your input!

 

[RxTree]

I would leave the light on longer. The plant senses the length of the dark period during which a hormone builds up. The plant does not seem to notice the length of the light period.

I wouldn't worry much, should be all good.

 

[Puscifer]

I would leave the light on longer. The plant senses the length of the dark period during which a hormone builds up. The plant does not seem to notice the length of the light period.

I wouldn't worry much, should be all good.

Please excuse my ignorance but what hormone builds up? Would this hormone build up have an adverse affect? VS leaving the lights on longer? Very interesting, tell me more

 

[Maj.Cottonmouth]

I would leave the light on longer. The plant senses the length of the dark period during which a hormone builds up. The plant does not seem to notice the length of the light period.

I wouldn't worry much, should be all good.

This is WRONG! DO NOT LEAVE THE LIGHT ON!

I have not had to do this myself but I have seen many threads on here about it and the experienced growers always say to have a longer dark period. A longer light period will make the plant think it should still be vegging and could cause hermie problems if you give it more than 12 hours of light.

 

[Puscifer]

This is WRONG! DO NOT LEAVE THE LIGHT ON!

A longer light period will make the plant think it should still be vegging and could cause hermie problems if you give it more than 12 hours of light.

This is the EXACT type of stress on my plants I'm trying to avoid!

 

[KONY]

This is WRONG! DO NOT LEAVE THE LIGHT ON!

I have not had to do this myself but I have seen many threads on here about it and the experienced growers always say to have a longer dark period. A longer light period will make the plant think it should still be vegging and could cause hermie problems if you give it more than 12 hours of light.

QFT.

Definetly do not leave the light on longer. Thats a good way to get nanners. Leave the light off one night for 24 hours OP. I mean when the light normally is about to turn on in the am, just leave it off an extra 12 hours, if you have a plug in (non dgitial) timer, unplug it 2-3 minutes before the light would turn on, and plug it back in 12 hours later....

I've switched to complete opposite light schedule a few times over the past few years and have never noticed any negative effects from leaving the light off for 24 hours.

 

[Stond_Face]

^^^^^^^ true dat! ^^^^^^^^^^

 

[RxTree]

It is the hormone that triggers flowering.

Essentially the hormone begins building up as soon as it is dark and continues until it is light. Because the hormone builds during the dark cycle, I believe that the dark cycle time of 12 hours is more important to maintain than a light cycle time of 12 hours. Thus leaving the lights on until the new schedule is reached should keep the hormone levels closest to normal.

Some people put their plants into the dark for 36-48 hours at the beginning of flowering to startle the plant into flowering by pumping up the hormone.


Excerpt from wiki "Plant hormone", emphasis is mine:

Auxins


The auxin indoleacetic acid
Auxins are compounds that positively influence cell enlargement, bud formation and root initiation. They also promote the production of other hormones and in conjunction with cytokinins, they control the growth of stems, roots, and fruits, and convert stems into flowers.[11] Auxins were the first class of growth regulators discovered.[12] They affect cell elongation by altering cell wall plasticity. Auxins decrease in light and increase where it is dark. They stimulate cambium, a subtype of meristem cells, to divide and in stems cause secondary xylem to differentiate. Auxins act to inhibit the growth of buds lower down the stems (apical dominance), and also to promote lateral and adventitious root development and growth. Leaf abscission is initiated by the growing point of a plant ceasing to produce auxins. Auxins in seeds regulate specific protein synthesis,[13] as they develop within the flower after pollination, causing the flower to develop a fruit to contain the developing seeds. Auxins are toxic to plants in large concentrations; they are most toxic to dicots and less so to monocots. Because of this property, synthetic auxin herbicides including 2,4-D and 2,4,5-T have been developed and used for weed control. Auxins, especially 1-Naphthaleneacetic acid (NAA) and Indole-3-butyric acid (IBA), are also commonly applied to stimulate root growth when taking cuttings of plants. The most common auxin found in plants is indoleacetic acid or IAA. The correlation of auxins and cytokinins in the plants is a constant (A/C = const.).

 

[Pointswest]

Extend the dark cycle until the new schedule is ready for the daylight cycle. 24 hours of dark will be better for the transition to the new lighting cycle. The 24 hour dark period will not affect the flowering initiation, but the 24 hour light cycle would stop the flower initiation, it would not be enough to reverse the flowering cycle, but will slow it down a little if switched with the long day cycle.

 

[Maj.Cottonmouth]

Nevermind, too stoned for simple math it appears

 

[Puscifer]

It is the hormone that triggers flowering.

Essentially the hormone begins building up as soon as it is dark and continues until it is light. Because the hormone builds during the dark cycle, I believe that the dark cycle time of 12 hours is more important to maintain than a light cycle time of 12 hours. Thus leaving the lights on until the new schedule is reached should keep the hormone levels closest to normal.

Some people put their plants into the dark for 36-48 hours at the beginning of flowering to startle the plant into flowering by pumping up the hormone.


Excerpt from wiki "Plant hormone", emphasis is mine:

Auxins


The auxin indoleacetic acid
Auxins are compounds that positively influence cell enlargement, bud formation and root initiation. They also promote the production of other hormones and in conjunction with cytokinins, they control the growth of stems, roots, and fruits, and convert stems into flowers.[11] Auxins were the first class of growth regulators discovered.[12] They affect cell elongation by altering cell wall plasticity. Auxins decrease in light and increase where it is dark. They stimulate cambium, a subtype of meristem cells, to divide and in stems cause secondary xylem to differentiate. Auxins act to inhibit the growth of buds lower down the stems (apical dominance), and also to promote lateral and adventitious root development and growth. Leaf abscission is initiated by the growing point of a plant ceasing to produce auxins. Auxins in seeds regulate specific protein synthesis,[13] as they develop within the flower after pollination, causing the flower to develop a fruit to contain the developing seeds. Auxins are toxic to plants in large concentrations; they are most toxic to dicots and less so to monocots. Because of this property, synthetic auxin herbicides including 2,4-D and 2,4,5-T have been developed and used for weed control. Auxins, especially 1-Naphthaleneacetic acid (NAA) and Indole-3-butyric acid (IBA), are also commonly applied to stimulate root growth when taking cuttings of plants. The most common auxin found in plants is indoleacetic acid or IAA. The correlation of auxins and cytokinins in the plants is a constant (A/C = const.).

If I'm reading this correctly (and mind you, I'm medicated right now) then leaving the lights on longer will deplete Auxin levels, which is not a good thing...
I have to agree with the general consensus that lights on longer would have more of a negative affect than lights off longer.

 

[Esrar]

I've switched to complete opposite light schedule a few times over the past few years and have never noticed any negative effects from leaving the light off for 24 hours.

Same here. Never had a problem with extra dark time. Thats my vote.

 

[whatsupdoc]

Fascinating. Awesome thread.

 

[Puscifer]

Wanted to update; I left the lights off longer in order to change the schedule and they all look fine. No different than if it was just 12 hrs of darkness.
Thanks everyone for your input

 

[Cainea]

I had to do this a few times myself for the same reason and I always extended the dark period and never had any issues.

Prolonging the light period doesnt feel right to me and I assume it could lead to minor reveg and extended time of flowering/less yield

 

[Grass Lands]

I've done it both ways...lights on and lights off for an extended period of time to get the 12/12 where I wanted it to be...

 

[fido]

This is WRONG! DO NOT LEAVE THE LIGHT ON!

I have not had to do this myself but I have seen many threads on here about it and the experienced growers always say to have a longer dark period. A longer light period will make the plant think it should still be vegging and could cause hermie problems if you give it more than 12 hours of light.

thank you
fido

 

[fido]

Wanted to update; I left the lights off longer in order to change the schedule and they all look fine. No different than if it was just 12 hrs of darkness.
Thanks everyone for your input

thank you
fido