24hr dark period before flower?

myth....

and an old one at that ...

 

No your friend is right, Plants have chemicals in the leaves that use light to tell them what phase they're in, these chemicals are either light or dark, and during long periods of dark and light, they change from light to dark, so giving them the 24 hr right before starting the flowering, gets more of them to turn dark and tells the plant it's time for flowering. Also, depending if you used 24/0 lights during veg, its a good idea to slowly work them into longer dark periods, going from 24/0 straight to 12/12 can stress the plant, so it's best to go from 24/0 to 18/6 to 16/8, then give it one 24 hour of dark before switching to 12/12.

 

If going from 24/0 to 12/12 stresses the plant, wouldn't going from 16/8 to 0/24 stress it even more? I'm not trying to be argumentative, but I'd like to see some evidence about this.

 

Nothing but an Urban Legend dude...

There is no scientific fact that proves this.

The plants "Hormones" only kick in after about 2 days of 12/12 cycle.
There has to be a repeated pattern of lighting "on" and "off".

We are trying to mimic weeds growing environment inside.
There has never been a 24 hour dark cycle in nature.

Think about it.

Freak

 

HUH .. chemical turning dark?? WTF ???

cannabis responds to dark periods. but giving a plant ( unless it is just before harvest) 24 hours darkness B4 flower doesn't do squat, except add another stress to its flower cycle

and what kind of ritual is that ? if it is so productive why then doesn't every one do it .. why doesn't RC Clarke mention it?

source Marijuana Botany (Chapter 1 )
Wharf

 

just set it to turn on at 10:00 , and off at 10:00 ( 22:00) and forget it .. do it during light on ...

 

Well, that just not true, alot of places in the North has one month of 24/7 dark and light. And in fact, one of the best outdoor strains ever grown was thanks to this 30 days of light, ever heard of Alaska Thunder Fuck?

And something I figured out is, that thoughtline is just pretty much wrong anyway, cause, think about it, if you just happened to find some crops of weed growing out in the forest somewhere, and noones been there for years, so this stuff is 100% natural, it's gonna actually suck compared to some of the hydro strains we can get from Amsterdam and Cali and such. For one, the soil in nature is far from perfect in nutes compared to the perfect nutes an experienced hydro grower gives their plants. Also, lighting, yes lighting, even though we're trying to reproduce the light of the sun, in nature you can't get the type of side lighting you can give your plants with CFL's, putting them only a few inches away from the plant, even, literally putting a bulb inside a plant's canopy to make sure lower branches get as much light as possible(an extreme case I know but I've seen the picture!)
True there's no 24 hours of dark in nature, but then how long does it take to get a crop grown outdoors versus how long it takes an indoor grower to get one? I've read several people saying they're sure that the 24 hour dark period before starting the 12/12 light cycle made it start kicking out flowers sooner, and it definanatly won't hurt the plants, so, you can go ahead and mimick nature if you want, in fact, if you really want to mimick nature, what you really need to do is flower under a 16/8 light schedule for the first couple months, Jorge says it will, it just takes 32 days to start flowering that way. The fact is, plain and simple, using indoor methods to speed the process, and improve the quality of nature works.

 

Actually you're right, I forgot part of it, going from 24/0 to 12/12 before preflowers have shown can induce stress on the plant.


Actually, something I thought might be the case with the 24 hour dark before starting 12/12, would probably speed up the preflowers production with plants that went through 24/0 light during veg. Jorge says that plants getting 18/6 during veg will show pronounced preflowers, where 24/0 might have them, but just barely, if they're there at all. So, it makes sense that Vegging at 24/0 light, then giving it 24 hours of dark gives it the signal to go ahead and preflower, which might seem like its flowering quicker than a plant that went through dark during veg, and therefore already has its preflowers, the 24 hours of dark wouldn't do anything in that case.

 

I've done this, it works fine and doesn't stress the plants at all.

We aren't trying to mimic nature with indoor grows, we are trying to maximize the conditions that the plant has evolved to respond to, and that is a big difference. For example, many of us give 24/0 veg light but that doesn't mimic nature. Neither does giving 18/6 for six straight weeks. Nor maintaining constant temps and humidity. Nor does feeding high-octane ferts nor watering precisely when the plant needs it and not more. Neither does using cross-bred genetics in the first place, for that matter.

As Wharfrat said, the plant reacts to the length of the dark cycle to trigger the hormonal reaction to flower. The idea behind giving extended dark when switching to 12/12 is to "jump-start" this reaction, that's all. And I've found that it does. At best this technique could start actual flowering a couple days early, at worst it does nothing.

There is a completely different reason that you might want to give extended dark when switching to 12/12, purely logistical and nothing to do with the plant's development -- with indoor grows we control the cycle and ideally put the plants on a schedule that works best for us, the growers. So sometimes we may need to change our plants' schedule to fit our own or to better fit our grow conditions. For example, I tend to run 18/6 veg not because I believe that is better lighting than 24/0 but because my grow op is in my garage and so is somewhat subject to ambient temps, and it can get pretty warm in there so I go dark from 12p-6p so as not to add extra heat. Some of us also need to match our light cycles to our work or school schedules so that the plants are dark while we are away and light when we are available to tend to the plants.

If you do need to move your light schedule around you should do so during veg by extending light or shortening dark, never by extending dark, because you don't want to trigger the flower reaction. To move your light schedule during or starting flower it's the opposite -- extend dark or shorten light, never extend light, because you don't want to disrupt the flower reaction.

 

I know this is a old post, however, she i searched a topic, this is one of the results, and I just wanted to comment on the "We are trying to give the plant the same treatment it would get outside independent!  That is a ridiculous thing to say, being the fact that, we wouldn't have this site, it would only be about harvesting and smoking weed, because we wouldnt even have to do anything but pick it off the plants, I'm just saying!  And yes I'm a newbie

 

Ask yourself when in doubt....what does mother nature do....she don't turn the sun off for a day...ideally it makes sense that the best change would be to shorten the "lights on" time over a few days at least. If you just want to force your plant to grow faster or bigger, there are better ways to do it I think.

 

Just something I read!! Dutch professional growers can leave it in dark before the 12/12 for 36 hours!!!

Sent from my SM-N9005 using Grasscity Forum mobile app

 

ok so reading the first page and a half I dont know if the subject has been solved yet but heres my understanding, as a horticulturist student, of how this all works. 
 
Marijuana plants have a tipping point between the light and dark cycles. When the plant builds up a certian amount of the flowering hormone, due to shorter days and longer nights, It begins to flower. So that being said when you give the plant 24, 36, or even 48 hours of darkness, the plant obviously builds up ALOT of the flowering hormone, thus kick starting the plant into flower immediatly, just about, statistically much much quicker than it would to wait for the plant to relize shes only getting a certian amount of light.

 

ever read the growers bible? I'd look into it everything and anything you need to know. Allot of prof growers in Amsterdam actually leave there lights of for 36 hours before inducing flowering, all it does is kickstart your plants a couple days to start flowering. I've experienced no bad results of this.
 

 

I've don't both, 24 hours darkness and no darkness before flower.

It really made no difference in the end product.

 

Sure op just put it in the dark for a few days and find out!
Mine switch to bloom quicker when I leave em in the dark for a long time !

 

anecdotal at best, sort of like harvesting before the lights come on. An experiment showing some significant increase in resins would sell me. Significant would be anything over 2% increases.