24/0 vs. 18/6 debate is over!!!!

Bluntguts

Member
recently my power went out for two days. my plants are on their last week of nutes and i will begin flushing within a few days before harvest. I've heard of people doing 72 hours dark prior to harvest with some controversial results however this happened to me a day ago and just seeing if anyone has had this issue come up. did my plants think go into a phase where they dumped all there energy into the buds before they are actually ready for harvest. should i just flush and harvest now or will they be fine. I know the final week or so is crucial to the outcome of the nugget. the trichs are not cloudy yet but almost all hairs are brown. I also was wondering if anyone has ever experimented with 24 hour light and 24 hour dark 48 hour cycle during flowering. if it will work, sounds silly but Ive heard of this type of thing effecting other species of plants in interesting ways. just a thought. I'm done with my crop and no clones this time so I can't experiment with this untill my next place. but to the first question maybe someone can help me out with some advice.
 
so i'm on 24/0 in veg but some strains arnt showing pistils when it goes in flower and i think its causing some stress. should i 18/6 or 20/4?
 

anonymuss

Well-Known Member
:bigjoint:"Most green plants are classified as either C3 or C4 which represents how carbon(C) is used during photosynthesis.

C4 plants temporarily store carbon dioxide(CO2) over the dark period to use for photosynthesis during the day. C4 plants slow down photosynthesis once the stored CO2 is used up and they need to gather it from the air. Which is why trees slow down photosynthesis in the afternoon even though the sun is still bright. This does NOT apply to cannabis.

C3 plants(:leaf:cannabis/veggies) gather CO2 only during the light period when they are photosynthesizing. During the dark period these plants only use oxygen for their metabolic life processes. They don't uptake CO2, nor do they use it. As soon and as long as the light is on, C3 plants gather and use CO2 for photosynthesis.

C3 plants also have the ability to use higher concentrations of CO2 than what is found in the air. If the light is bright enough and the plants have sufficient nutes, their growth rate will accelerate from it(2000ppm vs. 400ppm of CO2), which increases yield. They can do this continuously, without a dark period throughout the vegetative stage.

The dark reaction is a process of photosynthesis that takes place in both darkness and light. It uses ATP and NADPH molecules that hold energy absorbed from light to break apart CO2 into it's base components.

Again people get anthropomorphic with their plant needs. People need rest, so plants must too. This is false as well. Light means growth. Scientifically. Although 18/6 will shock your plants less when you switch to 12/12, it's a personal choice whether you would rather sacrifice a little growth for a quicker adjustment or less photo confusion. If you want to save money or energy that's a personal choice too. Do what you need to do to make your growing scenario work.

Another factor to consider, your ballast/starter life will be shorter the more you turn it on and off."

Hope this helps.:bigjoint:
money and energy thats all. couldnt care less about letting them sleep. leave them at 18/6 for too long and they will start to flower themselves very slowly.
 

findme

Well-Known Member
money and energy thats all. couldnt care less about letting them sleep. leave them at 18/6 for too long and they will start to flower themselves very slowly.
true but didn't someone here do a test ad found 20/4 to be the best for veg?
 
Very informative thread for me. I've learned so much from the past few weeks of reading here. I must thank mafuki and others for the excellent facts presented.:clap:

I've been on 24/0 from bag seed for a week in starter soil. They went in the soil on 10/2 and 10/3. My leaves are looking huge for only 5-7 days in and using cfl's. The second set of true leaves are coming in and the plants are so short that the first set of huge leaves on one of the plants is touching soil. I moved the soil out of it's way a little. Gonna start minimal Fox Farm nutes as soon as the second leaves are in and should be very soon.:-P

What I learned here is if I switch now to 22/2 , I'm convinced I can lengthen the stems a little while not stretching the plant out like it would in 18/6. Keeping it short and stocky is my goal. Here is my plan based on what I've gathered:
Week 1 (24/0)
Week 2 (22/2)
Week 3 (22/2)
Week 4 (22/2)
Week 5 (20/4)
Week 6 (20/4) (If needed)
Week 7 (18/6) (If needed)
Week 8 or 9 - Flower (12/12)

If they start to stretch more than 1" or so I'll try to adjust accordingly.
 

Ganja viewer

Well-Known Member
Well..., I'm on my first grow ever using wh. Russian seeds. I think I'm leaning towards the 24/0 cycle for vegging(started already). Received seeds last Friday at 2pm, soaked til 11pm and put in soil mix of starter mix/fox farm potting/fox farm ocean/ and some perlite in 3" peat pots. By Sunday, 100% germ rate and by today at an average of 2 inches on 12 plants with 2nd set of jagged leaves poking up on a few!

I've been reading constantly for weeks now and have decided on 24/0. Some say that the plants store energy for the dark period, like a battery that is charged. But a re-chargeable battery will also last for quite a long time longer if it is always charging and never gets drained, or used! So I've decided to keep my plants on the charger constantly! Yes, there is plenty of debate on the subject, and people prefer one way or another, but my plants are responding fabulously on 24/0 and are only 5 days and 5 hours from receiving the seeds in the mail!!! 2" tall already! I've read grow journals that the seedlings were at my height after 2-3 weeks from start of germing! Maybe I just lucked out (so far!), but I've done a lot of research and have been trying to take the majority consensus plus add my own little methods(such as soil mix) to the equation and things are going good. 24/0 or 18/6 is the hardest to determine from everyone swearing one way or the other, but I'm on 24/0 now and don't have any complaints! Will probably lower light gradually for 2 hours a day(last 6-days) until I hit 12/12 and flower-time to avoid major stress on plants. Just my 2 cents, from a newbie... 2- 4' 40 watt shop light flourescents for 2 days and now under 400 w mh at 16" away(started at about 21" and lowered the last 3 days evenly. 50% humidity and about 78-82 degrees in day, a tad lower at night due to the house cooling down. Closet 5x6x8, grow area 4x4, 80-90 cfm ceiling fan installed, fan on floor when needed to strengthen stems and blow cooler air in from room, and a 1/4 strength of big bloom in water since day 3, but will start alternating w/just water starting tonight. ;-)
 

sebastopolian

Well-Known Member
I have had some Mother plants for three years, One room is 18/6 an one room is 24/0. I never had any problems or have never seen them change with the 18/6, and have had several different strains. They of course turn into huge ass trees. LOL Peace and Happy growing.
 

uhavealighter?

Active Member
I can see how 24/0 is better than 18/6, but my theory is a bit complicated...i'll explain.

Photosynthesis creates food energy, but Respiration turns the food energy into energy to grow and for other life processes. Photosynthesis, at ideal temperatures (60-86F for pot), creates more food energy than respiration uses during light hours. At nighttime there is no photosynthesis, but the plant is still respiring, using the stored energy to keep growing and breathing. Photosynthesis and respiration rates do change with temperature, however, and are actually equal when temperatures get high enough(96F).

Maybe a higher temperature would be optimal for 24/0 light cycle, because all you are doing in lower temperatures is constantly storing energy when it can be used. I'm not sure if this is actually true, but it would definitely make sense. There has to be more things that are affected by higher temperature.

I would do an experiment on this....
Have an 18/6 set for 86F during day and 72F at night(this has proven to be optimal growth when temperatures are about 10-15 degrees below nighttime)
Have an 24/0 cycle with a temperature of 94F. (you don't want the temperature to be too close or the plant respiration rate might be larger than the photosynthetic rate and that's bad)

If you disagree please explain.
 

tkowitha123

Well-Known Member
Yin and Yang everything needs a balance, I personally do the 18/6 thing and it seems to be a good balance for my veggies on the other hand 24 hours of day light for clones in the first week of cutting seems to help rooting in my experiance.
 

dr.tree

Member
hps all the way 24/0- why because it's easy- the bag that the dirt comes in works great as the pot.
 

cat of curiosity

Well-Known Member
:bigjoint:"Most green plants are classified as either C3 or C4 which represents how carbon(C) is used during photosynthesis.

C4 plants temporarily store carbon dioxide(CO2) over the dark period to use for photosynthesis during the day. C4 plants slow down photosynthesis once the stored CO2 is used up and they need to gather it from the air. Which is why trees slow down photosynthesis in the afternoon even though the sun is still bright. This does NOT apply to cannabis.

C3 plants(:leaf:cannabis/veggies) gather CO2 only during the light period when they are photosynthesizing. During the dark period these plants only use oxygen for their metabolic life processes. They don't uptake CO2, nor do they use it. As soon and as long as the light is on, C3 plants gather and use CO2 for photosynthesis.

C3 plants also have the ability to use higher concentrations of CO2 than what is found in the air. If the light is bright enough and the plants have sufficient nutes, their growth rate will accelerate from it(2000ppm vs. 400ppm of CO2), which increases yield. They can do this continuously, without a dark period throughout the vegetative stage.

The dark reaction is a process of photosynthesis that takes place in both darkness and light. It uses ATP and NADPH molecules that hold energy absorbed from light to break apart CO2 into it's base components.

Again people get anthropomorphic with their plant needs. People need rest, so plants must too. This is false as well. Light means growth. Scientifically. Although 18/6 will shock your plants less when you switch to 12/12, it's a personal choice whether you would rather sacrifice a little growth for a quicker adjustment or less photo confusion. If you want to save money or energy that's a personal choice too. Do what you need to do to make your growing scenario work.

Another factor to consider, your ballast/starter life will be shorter the more you turn it on and off."

Hope this helps.:bigjoint:
well writ. too bad botany, biology, and earth science aren't popular to pot growers...
 

kushlatte

Member
I just switched from 18/6 to the Gas Lamp Routine (12/1) to save energy. Will post results and comparisons soon. GLR is 12 on 5.5 off, 1 on(to inhibit flowering) 5.5 off
Saves a ton of electricity and heat which I need
 
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