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Some of the best things happen during the dark

Discussion in 'Indoor Marijuana Growing' started by ralex999, Aug 29, 2009.

  1. I have been reading some post that basically is pushing 24 hours of light. I needed to set the record straight. The common misconception is that everyone knows Marijuana needs light for photosynthesis but what most miss is they need darkness as well. We all have a hunch that plants need some sort of darkness, but we really do not know why. It's not that simple and it requires touching on a number of things to hone in on the whys and wherefores.

    Our beloved marijuana plants are not as simple as some would make them out to be. They are far more complexed than “just a weed”. In the evolutionary chain if you match up a MJ plant with say an single cell organism, you would get the point quite clearly. Our plants are extremely complicated energy generating machines that function both in the sunlight and under the cover of darkness.

    OK, here is where it gets a little complicated but bare with me; During daylight hours, our beloved Mary Jane takes in the light energy, some water and some air (CO2) to start the process known as photosynthesis and generates sugar and oxygen that is the building blocks of the cell energy and the release of CO2 into the atmosphere. However, carbon dioxide is generated in the dark side and is the source of carbon needed to maintain molecules. Without this dark period, it just does not produce the necessary amount of carbon to not only create molecules but to expell some of them.

    People tend to forget that Cannabis is not a new plant. It is prehistoric in nature and brings with it a long history of very complexed evolution. This thing was around during dinosaurs (no wonder they were so happy) and acted totally different than they perform today. Heres how: during the days of the dinosaurs, the atmosphere was basically carbon dioxide rich environment. Through evolution, plants did us a favor and started converting this carbon dioxide into oxygen. Lucky for us.

    As the world started changing, so did the Cannabis plant and plants in general as far as that goes. As the world changed in things like Temperature, Humidity, light conditions, cloud formations, daylight hours, extreme conditions such as heat and cold, and other environmental factors, the plants changed also. It is thought that the Cannabis plant started somewhere up in Tibet along the Himalayas but quickly moved South like so many snowbirds do to Arizona. As conditions changed, so did the neighborhood. Cannabis adapted, just like humans did. CO2 levels went down as the environment changed. So plants had to adapt to about 0.036% or 360 ppm.

    So heres the deal: we are growing inside and trying to duplicate by artificial means the outdoors. So once we understand that we are merely duplicating natural conditions, we can then create better metabolic activity. I know I am going the long way around the track to get to a point, but I have to cover some basic ground to get to darkness. This is where it gets a little muddled. When the sun goes down, actual changes occur in a whole bunch of ways.

    The first is the amount of lights wavelengths. We read tons of threads on Kelvin, different wavelengths and lights but really don't understand what these threads are really talking about. Look at it this way; when the sun sets, the angle of the light hitting the earth's atmosphere is tilted. It changes from bright daylight (white) blue spectrum (450 nm) to amber or red at sunset (650 nm) which is basically a shorter wavelength and thus carries with it more photon energy. That is why we need more red to flower (HPS during bud) and we need more white (Metal Halide) during veg stage. We are duplicating nature indoors. Basically humans developed in a similar way as we spend the day gathering food and expending energy. At night time, like cannabis, we metabolize this food to produce the energy to make new cells and repair the damaged ones we hurt during the day. We also use the night to produce very important enzymes and proteins and we wait for the sunrise to get to work or in a plants case, to start the day again photosynthesizing.

    I know we are getting a little technical here and if you really want me to screw this thread up, let me introduce what the plant is really doing while it is sleeping is carrying out a cyclic process known as circadian rhythm from the Latin word meaning “approximately a day”. To take it one step further, all cells require metabolic energy in the form of what is called ATP or NADH. This energy is produced throughout the day and is the result of many biochemical processes, not just one. We all seem to concentrate on photosynthesis because we know it occurs during the daytime and we can understand that. Photosynthesis is the process of breaking down metabolic energy by using light energy (Produced during the day) to break apart water which generates O2, protons and electrons. Oxygen becomes the bus driver that transports all aerobic respiration and it is used to transport the electrons which in turn is used in the productions of those energy rich molecules known as ATP and NADH we talked about earlier.

    So when all of this mixes together in photosynthesis, the Calvin cycle ( light) fixates or concentrates on CO2 to make what is called 3-Carbon sugars during this light cycle. Later during the darkness or “night cycle”, this 3-Carbon sugars are converted to 6-Carbon sugars such as glucose and fructose. Now the point should be clear and obvious. We need both the daylight for photosynthesis to occur and generate 3-Carbon sugars but we also need the darkness or night to finish the job and create 6-Carbon sugars to make glucose and fructose that is used to make cellular carbon or the bulk of ATP and NADH during aerobic respiration during the dark cycle. Does this make sense now?

    Now we all read the Noob's desperate plea for help and how delicate the plant is. But it is really quite strong and we really have to fuck with it to screw things up. The cannabis will survive in a wide range of light, not just one, and under a wide range of temperatures. I am sometimes amused when I hear of temperatures being too high or humidity being out of range and I think of the tropics. Plants thrive there. And the last time I was in the tropics, it ain't no 72 degree's in an air-conditioned room. Temperature is however an important variable as it does effect humidity, dissolved gas concentrations, water stress, and is also an influence to the amount of water loss based on a ratio to carbon fixation, no laughing matter. The thing most noobs are yelling about is the leaf changes caused by light absorption , sugar formation and gas exchange. Back to the darkness, during the night the stomates in the leaves are closed to prevent loss of moisture and the need during sleep for gas absorption is not as great as during the day. During the day when demand is at it's peak, the stomata are wide open in the leaves as the demand for CO2 is at it's greatest. So when temperatures gets out of whack and rises, so does the loss of water through the very openings in the leaves stomata and the photosynthesis is maxed out at about 85 degree's but can handle a range from about 70 degrees up to about 95 degrees, a huge variable of temperature. So don't worry noobs, it can really be out of whack and still be viable.

    Lets start this thread and I will add additional comments as we move along. If no one joins in the discussions, then I guess no one is interested and we will all just live in the darkness, no pun intended. ;-)
  2. good job man, I wish I understood that stuff a little better, but good job, haha.

    drop some of your scientific expertise by my grow, it's in the sig!
  3. Couple of things. Cannabis is a C3 plant. Doesn't require darkness (except to flower, excluding autoflowering strains). Basic botany. ;)

    I'm not trying to duplicate nature indoors. I'm improving on it. :)

    Cannabis doesn't "need" more red or blue during any phase of growing. Many growers use MH or HPS entirely through the grow with no ill effects.

    Comparing cannabis to humans is a fools errand. The word for it is anthropomorphism.

    Been growing full time now for almost 8 years and have been using 24/0 light cycle for the majority of that time. No harmful effects whatsoever.

    Where a lot of people get confused is when the Calvin cycle is referred to as "the dark cycle". The Calvin cycle is light independent. Doesn't require dark at all.

    Besides opening a botany book and understanding it, I also have Mel Frank, Ed Rosenthal and Robert Connell Clarke agreeing and understanding basic botany. :smoke:
  4. Plants do grow in all shades of colors except for green. Red however does play an important role in the regulation of the dark cycle. Red is the color or the sun setting and the sunrise and basically is used in dark room working around film. Cannabis can regulate temporally most biochemical processes by circadian rhythm, a form of the biological clock. Such a process regulates something as simple as leaf movement, flowering or even ripening response. The main protein responsible for this is called phytochrome.

    Phytochrome comes from red light. That's how so many can go from veg all the way through using HPS (with its red spectrum) as opposed to using only Metal Halide and it's blue spectrum. So if you are faced with only one, I guess the way to go is HPS. Plants can also sense the movement of the sun in such as sun flowers follow it during the day but what they are following is the red spectrum with higher intensity at day break or sunset. Before I move away from this area, I want to touch on the biological clock for a moment as found in other parts of nature. That's the bird of Capistrano.

    For years, most scientist could not figure out how the swallows would leave their breeding grounds in Mexico to fly north and arrive at precisely the same day each year on March 19th. The answer was in the light. The start of the internal clock of the swallows begins on the shortest day of the year, Winter Solstice. This year, it will begin on December 21st, 2009 at 12:47 PM eastern standard time. By placing a hood over certain swallows, they could delay the start of their flight to Capistrano by exactly the number of days that the hood was placed over the birds. So darkness does play an important role on not only the cannabis, but other forms of nature such as birds. I am sure you have grown for years with 24 hours of continual light, but it crosses my mind just how much better would your yield be if you possessed an open mind and looked at the lessons of Nature instead of knowing it all. Sometimes duplicating nature is indeed improving upon it by creating a “perfect environment”

    I have read Frank, Rosenthal and of course Cervantes as well as some of the great Botanist of all time and if you look closely, they will all say that darkness certainly has an effect and the basic switching to 12/12 is mandatory to bring bud into flowering.

    All I offer on this thread is a basic belief that 100% light during veg is not the end all, final answer to all of your problems. It may be what is creating some of them. I believe that cannabis does improve by getting a little rest. Many have successfully operated at 24/7 as many have also successfully grown at 20/4 as well as 18/6 and of course we all know what 12/12 does. So if this thread helps you in anyway grow a better crop, then I am all for it. If this thread opens up a discussion on possibly improvements to grow, well, I am all for that also.
  5. I guess I should also quote some of my sources for this thread;

    Vince-Prue, D. 1986. The duration of light and photoperiodic responses. Photomorphogenesis in Plants. Martinus Nijhoff, Dordrecht, Netherlands.

    Wiskich, J.T., Dry, I.B. 1985. The tricarboxylic acid cycle in plant mitochondria: Its operation and regulation. Higher Plant Cell Respiration. Vol 18: 281-313. Springer, Berlin.

    Zeiger, E., Farquhar, G., and Cowan, I. 1987. Stomatal Function. Stanford University Press,Stanford, CA.

    Cervantes, Jorge. 2006. Marijuana Horticulture, Van Patton Publishing, Vancouver, WA

  6. Oh please don't. :laughing:

    Again, anthropomorphism. Apples and oranges. ;)

    I would not put Cervantes in that group at all. He is factually incorrect on several things, including (wait for it), cannabis needing a dark cycle.

    Never said it wasn't (except for auto flowering ruderalis strains). In fact, I specifically addressed that.

    Making assumptions such as this does nothing to forward your argument. I have never claimed to "know it all", nor am I close minded.

    What I have done is I have used all manner of light cycles. I have grown 3 grows using only an MH light. I have grown two grows using MH for veg and HPS for flowering. I have settled on HPS for all stages because the yield and other factors prove this is the most productive light to use.

    As well, my family owned and operated a nursery for a decade. I have taken college botany courses and I have listened to those that have more knowledge than I. Some wonderful studies were published years ago, I believe by Tazawa. Haven't searched for them in a blue moon, but they might still be available through search engines. Definitely worth the read.

    This is a direct quote from Ed Rosenthal:

    Need the dark | Cannabis Culture Magazine
    The following information is straight from Greg Green's "The Cannabis Grow Bible"

    And of course Robert Connell Clarke

    As for your thesis on ATP and NADH, for C3 plants, dark is not needed for the reactions:

    Photosynthesis 1
  7. well this is a very informative thread. deff a good read. saving this one and seeing where the discussion goes. this is deffinatelly something i want to know more about. keep the information flowing fellas. :smoke::smoke:
  8. I think there are as many different ways to grow as there are growers. Hydroponics did not make much headway until the fifties and then only limited. Someone had to think up Deep Water Culture as well as Ebb and Flow, NFT as well as many combinations of "all of the above". Many ways work for many different people and I certainly do not wish to come across as "my way is the only right way". That was the purpose of this thread was to invoke a response and hopefully a meaningful discussion.

    There are some out there that are swearing by LED lights and I believe there is a lot of room for progress in that area but I am not about to switch from the tried and proven methods of my HPS and yes, I also switched from MH for veg to HPS three weeks after clone to Bud. I think it is a softer gentler way of bringing them to harvest but that is personal opinion not based on facts nor supported by scientific data. However, there is just too much out there in regards to scientific research that indicates veg a little bit longer, put em under a scrog and give em a rest. But not all agree with that and to them, I wish them well. They of course are entitled to their opinion and I hope it works out well for them.

    Rosenthal, Green and Cervantes all have different ways of doing things. I think if you go out and do a survey of commercial growers in Holland, Canada and Northern California, you would find far more on a sixteen to Eighteen hour light cycle than you would ever find those running 24 straight. I would be very interested in this thread if others would post their light cycle and why?
  9. To continue on with the reasons I feel it's best to give em a rest is in the area of Phytochrome which is triggered by red light spectrum (650 nm). A point to note however is it can be reversed by far red light (720 nm). I would tend to be a little careful with too far on the scale such as Infra red or far red and stick with the tried and proven lights such as HPS. That is why I am not so high on the LED stuff and feel that they could inadvertently mix the wrong color spectrum into the light combination and your plants would stop growing and you would not know why.

    The phytochrome is why plants can sense the movement of the sun and have you ever noticed your plants leaning towards “the light”? Cannabis are grabbing whatever photons they can get, from any direction they can get it from and interrupting the dark cycle with light can dramatically alter its circadian rhythm as in the case of introducing light during the 12 hour darkness cycle of Budding. One note, Phytochrome has been noted to make a response in the blue spectrum (450 nm) which in my opinion is the reason you get a limited success out of MH during flowering. But again, if I had only one choice and could go with only one bulb, I would go with HPS.

    Some have quoted in earlier post that continuous light effects the growth, quantity of harvest and other measures. I disagree. Cannabis energy metabolizing systems function on many different plains and on many different levels. A biochemical pathway can only proceed as fast as the rate limiting enzyme or substrate. The primary source for regulation is genetic, not 24 hours of light as an earlier poster quoted greg Green on. The thing I like most about Green is he tries to give you both sides of the argument but in the case of 24 hour light, I feel he is dead wrong.

    Chloroplasts and mitochondria have their own genetic code that produce the enzymes needed for their respective process. The only way to up-regulate genetic expression is either through genetic engineering or producing more of these genes by making sure the plant has all its required nutrients to produce more new cells. Another mode of regulation is through the limiting pathway intermediate, as mentioned regarding CO2 supplementation where the limiting factor becomes the regeneration of ribulose-1,5-bisphosphate. Unfortunately, the regeneration of this substrate is also regulated by the electron transport chain.

    Sometimes a limiting reactant can be artificially added to increase metabolic activity, as in the addition of amino acids, hormones and cofactors like trace vitamins and minerals. Ultimately, the major mode of regulation is environmental. Changes in water properties, nutrient availability, temperature, light duration and strength, humidity, and dissolved gas concentrations are big obstacles that need to be orchestrated to achieve maximal metabolic activity.

    Now that I have pissed off the masses, let's hear what you have to say about 24 hours of lights.
  10. Honestly, i vegged under 24/0 for 60 days, and then i switched to 18/6 for 2 weeks, and my plants grew more in the last 2 weeks then a month under 24/0. BUT i also lst'ed a different way than i have read, in that i staked the main stem to the ground. i have between 5-7 shoot on 4 plants, 9 on anouther, so that may have something to do with the growth, like a discrepency.(sic?)
  11. #11 FenceWalker, Aug 29, 2009
    Last edited by a moderator: Aug 29, 2009
    The thing you seem to be ignoring though is that even agreeing with your "primary source of regulation is genetic", if you have 6 hours of dark, that is 6 hours that the plants aren't photosynthesizing. So conversely, adding those 6 hours of light will (as botanical science, Ed, Mel, Robert and Greg all agree on) will provide that much more growth instead of "down time".

    They will still be reacting at the same rate, but have 6 more hours to do it. ;)

    I get you disagree with botanical science, Ed, Mel, Robert, Greg and myself. As long as all the other folks reading this understand your stance is not based on proven science, it's your opinion. :)

    Now this discussion seems to have reached an impasse and as I've shown (with links) what the science is, I'll unsubscribe and leave you to your "discussion".
    I found that with 18/6 I had more stretching (space between nodes), which can sure appear like "more growth", but most growers don't really like to see it.

    As well, when LSTing, you expose the secondary growth to more light which will cause them to grow more than secondary growth on a plant grown vertically. ;)

  12. well, if you do some research, there is in fact a reason why shifting towards red light assists the switch to flower.

    in fact, you even mention it...just not applying it. Phytochrome has a couple forms. The ratio of reacted phytochrome to blue, red, and far red light can and does serve as a trigger for flowering. In a 12/12 environment, its the reaction that keeps the plant in flowering each day.


    FenceWalker posted enough actual scientific information to satisfy my urge to qualify my statements. Before i clicked the link, I knew this was a C3 situation lmao.

    I love the phrase about plants stretching more in 18/6 vs. 24/0. Its true they may get taller more quickly, but if youre counting nodes, and measuring the average distance between nodes, youll notice the plants grown in 24/0 are more efficient.

    by efficient, I mean a better ratio of nodes per height. I dont care if your plant is 10 feet tall, if you only have 4 nodes, thats weak. Subsequently, a 2 foot plant can have a dozen nodes easily, and as such be considered a much more preferable plant to work with IMO.
  13. Some great points here, a good read, but what really impresses me is how you guys are "debating" and not fighting or pushing your own opinions. Lots of respect, great to see.
  14. I'm no expert... But as far as I know... EVERY time the plant is in darkness, it begins reactions and producing proteins that take 12 hours to complete so flowering can begin/continue.

    Isn't this process expending energy?

    It would seem that NOT initiating this sequence at all (24 hr light) would add to the available energy for growth?

    I've run 24 hrs before...the plants did fine...
  15. I hope fencewalker does not unscribe, he keeps us honest. I have always felt that a "difference of opinion" is not only healthy, but wise. I have never learned anything in my life by being right all the time. It is only wihen I really make a mistake and someone calls me out on it, that I truly learn anything.

    Civil is one thing, and I like that quote by Patrick Henry who basically said;
    "I disagree with what you say, but I will fight to the death your right to say it." And then the English hung em ;-) The difference in this board from so many others is the "lack of flame wars" because basically, we all have a horse in the race or Dog in the Fight. We all have common interest and honestly, I know of no one who really doesn't want the other guy to succeed. I have seen so much patience with newbies who ask some really stupid questions and then it occurs to me that "the only stupid question is the one that is not asked" and I try to be a little more humble and remember my first grow in the sixties when we didn't have a clue as to what was going on. Man, if I told you some of the shit we did back then, no one would believe me.

    In 1978, I built a Green House that was 120 feet long by 32 feet wide and planted 1,100 Tomato plants in gravel because I knew damned well what I would be growing inbetween those hummers the next crop. My holding tank was 8 feet by 8 feet by 8 feet and you rocket scientist out there can figure out how many gallons of water I was pumping three times a day for about a half hour. Back then, no one believed I could grow 1,100 plants in gravel, they said they would fall over. (I used tie downs and strings)

    My crop has always grown better when I give em a chance to rest up a bit. Could be habbit, could be genetics, could be many things, but I honestly feel that without at least six hours of darkness, my plants are just not as healthy looking. With rest, they seem happy and I know this is not very scientific, but when a time clock fucks up and I miss turning off the lights by an hour or so, the next day my plants are "hung over".

    One final note, Duplicating everything is now a priority with me. when I need one air pump, I install two. I have back up's for every system in the joint including timers now, fans and scrubbers. Everything. Good luck on your grow, if it works for you to grow with 24 hours of light during veg, by all means use it. If your plants seem healthier by giving them a rest, by all means do it. If you think you are right or you think you are wrong, you probably are....:hello:
  16. This is true.

    So is this.

    *glad amoril clarifies.

    for veg, you do NOT need darkness, to flower (unless auto-flower) you DO.

    now whether an 18/6 schedule will induce flowering faster after switching to a 12/12 or if going 24/0 then to 12/12 will , who knows? good test for you guys to try out.

    plants can pre-flower under 24/0 and 18/6 if you give them enough time... and they will continue to build up calyxes until darkness in induced, or until we can re-create/induce more PBr in plants under consatnt light.

    so really the debate here is a matter of preference over anything.

    i'm sure everyone here has seen very good results under either light schedule.
    but like i like to say, results can't be compared unless every condition for the plants are identical, even then, you can only have a close, comparison, nothing to live off of.
  17. ^^ good points

    Plus the OP referred to the Circadian Rhythm, but didn't give any insight as how this may apply to plants.

    And didn't give any info to back up the bold claim that plants can't do certain things during daylight hours
  18. #18 clos3tgrow3r, Feb 1, 2010
    Last edited by a moderator: Feb 1, 2010

    I am no expert and this comment is completely abstract but with due respect to botanists around the world I know that there are many things we have yet to learn about plants and there are many popular notions that in truth are misconceived. If growing weed was a simple task that only involved time and money then everyone would keep their lights on 24/7 until flowering, not to mention that there would be a lot more of us too;):D. But plants are not black and white and there is much we may never know.

    I am a conservative grower not to mention a new one. For the time being I am only trying to replicate nature not improve it as I heard you say earlier. I grow in organic soil (I also use diluted urine because apart from being nutrient rich it is commonly found in rich environments), I do strictly 18/6 veg and 12/12 flower (that is one deviation I accept), I have a fan set on a timer to control temps to go from early morning chill, morning sun, afternoon heat, then evening sun at their respective times during the day, I try to introduce as many natural light wavelengths as I can (including UV), and I do all of this for 1 main reason. The core essence of MJ has become what it is today over evolutionary time not during the human domestication of the plant. Deep time means hundreds of thousands of generations, each one working unknowingly towards becoming an ideal inhabitant of their environment. Who am I to suddenly change the world this plant has adapted to? We are meddling with extremely complex organisms that cannot truly communicate back to us. Who knows what unnatural genetically programmed function is activated in the total absence of darkness? Not that I am a hippie and that unnatural = bad. There are always exceptions. But all I am saying is if you dont know for sure, you are guessing, when you guess sometimes you make a mistake, and without communication, you may never even realize a mistake for what it is. But hey, then again for some people this can be a good thing it all depends on what your after i.e. more THC, bushier plants, quicker growth, stonier highs, ect. ect. on to infinity. What I am after is knowledge of the plant and so I try to learn from the plant in as natural of an environment that I can.

    Rabble Rabble Rabble, my opinion on the light cycle is that cannabis should get much more light than dark but that it should eventually get some time to rest. Even if the plant grows faster with continuously incoming energy, the fact that you have eliminated the dark period which the plant is probably expecting may lead to unhealthy plants. There must be many functions that are only activated when the plant senses a low or no light environment. These functions would be triggered based on evolution. Its not hard to assume that plants associate high light levels with activities that occur mainly during the day time (water-loss, pest activity, and who knows what else) and low light levels with night-time conditions. If there are certain functions that are better carried out during times of decreased pest activity, decreased water loss, or colder temperatures, ect., ect. then it makes sense for that plant to do these things at night--if that is the case a trigger based on photoreception can easily be formed. By having lights on 24/0 you may get bigger plants but they may also be unhealthy in ways a 18/6 plant is not. And to get the highest quality (not quantity) buds you must raise the healthiest plants.

    Hope this has made some sense im a little high:smoking:
  19. You claim that you're not trying to improve nature, yet you've got high-power lamps running 18 hours a day with oscillating fans.

    Guys, the idea is to saturate the plant with as much as it wants of everything, not just to replicate natural conditions or force as many nutrients as possible into it.
  20. #20 clos3tgrow3r, Feb 1, 2010
    Last edited by a moderator: Feb 1, 2010

    If you noticed I said that that was a deviation I accept. I accept it because I want to help my plants to grow faster and stronger and I acknowledge that by increasing their light intake my plants will grow stronger and faster. However, that does not validate the notion that increasing light exposure to the point of eliminating the dark period is the best method. I will not easily take a concept to the extreme, and therefore will not eliminate my dark cycle because I want to "saturate" my plants with light. You are applying simple linear thinking to a complex circumstance.

    EDIT: I do agree with you that we should give as much of whatever our plants want but that we must also do so with discretion--we should not give them so much of one good thing that we are unable to provide them with another!

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