18/6 Vrs. 24/0

[PatM]

Whatâ??s up everyone

Iâ??m new to growing, I never grew anything before, and im going to take a swing at it, I did my research on the forums and watched a few grow movies heres where im at so far

Flood and drain system
Rockwool cubes
4, 40 inch Cool and warm white fluros 6 inches from the plants
GH nutrients ½ strength
Ph 5.9
No ppm meter
seeds from some nice weed
Room covered in aluminum foil (Mylar is expensive)
Temp between 62-69 degrees

So im about 3 weeks in now, I was going with feeding twice a day and a 18/6 light cycle, with a fan on low
Well I was constantly dealing with droopy leaves so I cleaned my res and I changed my neuts
I checked my ph all the time, nothing worked

So I upped the light cycle to 24/0 and removed the fan, and threw a spray bottle into the mix(spraying with 6.0ph water every time I fed the plants) and they completely recovered , and not only that their thriving , thereâ??s roots busting out of the bottom of the 3 inch rockwool cubes everywhere

So I was wondering what happened here? Whatâ??s the advantages of an 18/6 light cycle compared to a 24/0 cycle in the early stages of an immature plant, and are there disadvantages of not having any dark time for the plants?

I was just wondering, if anyone wants to jump in here and explain this to me Iâ??d appreciate it and if not thatâ??s cool too, and if anyone has any tips or advice for a flood and drain set up that would be cool too, cause you donâ??t see too many people doing those, everyone is into the DWC bubblers and aeroponics, and im a newbie so whatever

Thanks

PatM Reviewed by PatM on 02-27-2006. 18/6 Vrs. 24/0 Whatâ??s up everyone Iâ??m new to growing, I never grew anything before, and im going to take a swing at it, I did my research on the forums and watched a few grow movies heres where im at so far Flood and drain system Rockwool cubes 4, 40 inch Cool and warm white fluros 6 inches from the plants GH nutrients ½ strength Ph 5.9 No ppm meter Rating: 5

[green4life]

mine like the dark periods, gives the nutrients time to cool as well, you want em at 65 F. or under 75 at least. Plant like the dark period too, because thats the way god does it

[PatM]

How come when I upped the amount of light and reduced the amount I fed them their condition improved? And why do the plants need the dark period of their not in the flowering cycle, other than to let the neuts cool?

[green4life]

my plants like low ppm 300 right now (4 weeks into veg.) so maybe in your case you are just finding the prefered levels (more isn't always better/ can cause nute burn). I think the plants like having a period of time when they arent recieving light, im no professor, but a break from photosynthesis might allow them to deal with it a little. give it 4 hours dark if you want faster growth, but mine are blowing up off 6 hours dark, and it's all about personal experience really. What works for me might not work for you, so at least you'll learn a lot when you make mistakes...... bla bla bla. happy growing!

-greens

[elcheapo]

Sounds like something else might be to blame for the droopy leaves. I think rockwool is one of those mediums that is always either too wet or too dry. I used to use 18/6 until I tried 24/0. Cuts the Veg time down considerably and allows you to check on them anytime of the day. Not sure yet which is more likely to turn the plant hermie. The stress of going from 24/0 to 12/12 or light leaks during 18/6. But I would bet its light leaks during 18/6.
Hopefully you have selected the appropriate bagseed for your grow. Poor selection may also result in hermies.

[britewire]

Plants need their dark period to convert the chemicals they have absorbed in the light period (i.e.anorganic CO²) into organic molecules that helps the plant to grow (The Kranz anatomy). This is called the CALVIN CYCLE.

This means, the plant converts chemicals and renews it'sself with help and sythese of those chemicals.

That's why I always use a 18/6 cycle for VEG. I've tried 24/0, but I've found the plants have less stress and look healthier when you give them their dark periode and opportunity to preform their CALVIN CYCLE.

Source: www.vc.bioscience.ru.nl

Greets Britewire

[Jdog7000]

I tryed the 24/0 lighting period and would probably never do it again.I think it is a tad stressful but nothin to worry about.But I think my plants would be doing better if I was doing 18/6.Infact I'm thinkin of switching, but I'm about to flower anyway so...

[elcheapo]

Interesting read. Good information. Finally someone has cleared this up once and for all. Cheers Britewire.

[LIP]

Green4life is right. 18/6 will give you better results because the plant is meant to be grown outside, and naturally it would get a dark cycle.

Although, saying that, i put mine lights on 24/0 for the first week, then as the first set of 5 fingered leaves come out i stick it on 18/6.

To answer your Q plants will grow quicker, and therefore, 18/6 is beats 24/0 for most cases.

[GluteusMaximus]

This is a really complex issue so please bare with me and I apologize for the lengthy explaination.

Plants can benefit from up to 20 hours of light. They require at least 4 hours of "rest" per 24 hours. If you keep the lights on 24 hours, the plants will each pick their own "rest" time. Plants prefer to "rest" in the dark but will "rest" in the daylight if they have to. If you have them trained on a schedule of say 18/6 and change the dark period to a different time of the day the plants will eventually adapt their rest period to the time of day you give them darkness, however, this takes time (days) to occure thus you rob them of some of the light period until they adjust.

Two good reasons to have a 20/4 hour cycle instead of 24/0.....

1. That you train all your plants to rest simotaniously so that when you change the cycle to 12/12, they are taking full advantage of the 12 hours of light (assuming the 12 hours of light are during the same time of day you gave them 18 hours of light). When I change light cycle, I have the lights turn off 4 hours earlier than my original 20/4 schedule and remain off 4 hours after.

2. You save electricity.

Plants droop when their water content is low. Plants are most perky when they have maximum water intake and respiration. Your plants were not achieving the maximum water intake which could have been a result of many factors (over watering, drowning of roots, not enough respiration, low room temperature, too much humidity, nutrient imbalance.....the list goes on and on).

When you started spraying the leaves, you compensated for the lack of water uptake from the roots, which was the right thing to do. You also increased the light cycle allowing the plant higher respiration capability. Now that your plants have recovered, I recommend you spray them less frequently and back the light down a bit and continue to monitor their reaction. You will better train them if you adjust the light and water cycle gradually (over a couple of days).

The best conditions, in my opinion, are to get the plant to operate like a water vapor.....sucking in as much water/nutrients as possible and evaporating it at it's maximum capacity. Too much light/heat and you risk respirating faster than the plant can uptake water thus drying leaves. Without enough respiration, your plants will grow slow and not uptake as much water/nutes as they're capable of. Over watering, you risk drowning the roots.

It's all about finding out what your room needs to make the conditions perfect for the specific plant you're growing. This is why we're all much alike. If it were too easy, we probably wouldn't do it.

GM