Yeah, almost all are, but that doesn't mean they all operate in the exact same way, and supposedly not all actually require a dark period. Cannabis ime does not. I fully acknowledge others can have other experiences.
"It's been established for many many many years now that cannabis is a C3 plant. It does not need a dark period. C3 plants gather CO2 only during the light period when they are photosynthesizing. As long as the light is on, C3 plants gather and use CO2 for
photosynthesis.
Some growers practice a version of anthropomorphism with their plants. They believe that since people need rest, plants do as well. Concerning cannabis, this is not true.
Every grower can make a personal choice about light cycle. They can save on their electric bill or prolong ballast/bulb life. 18/6 can be less of a "shock" when changing over to 12/12 for flowering than 24/0 or heat issues can be addressed by fewer hours of light, but basic botany has proven long ago that cannabis needs no dark period."
Robert Clarke "Marijuana Botany: An Advanced Study"
"Marijuana plants photosynthesize as long as they receive light as well as water, air, nutrients and suitable temperature.
Photosynthesis is the process in which plants use the energy from light (primarily in the blue and red spectrum's) to combine carbon dioxide (CO2) from the air and water (H2O) to make sugar while releasing oxygen to the air.
Plants use sugars continuously to fuel metabolic processes (living) as well as for tissue building. The plant combines nitrogen (N) with the sugar to make amino acids, the building blocks of proteins. They are the substance of plant tissue. When the light is off, the plant's metabolic processes, respiration and growth, continue.
The plant can photosynthesize continuously so it produces the most energy and growth when the light is on, continuously. Continuous light does not stress the plant, which reacts somewhat mechanistically to it.
>Plants under an 18-6 light-dark regimen are producing sugar only three quarters of the time. They are thus growing at only 75% of their potential. Leaving the light on continuously will result in bigger plants, faster, which leads to higher yields."
Ed Rosenthal "Marijuana Grower's Handbook"
"Cannabis is a light demanding plant. Professional growers keep the light on their plants using the 24/0
photoperiod for this reason. Plants that grow under 24/0 flourish and do not need a quantity of darkness in order to rest and perform
photosynthesis properly. Plants that are grown in optimal conditions under 24/0 light regime grow vigorusly and the benefits of a 24/0
photoperiod can be seen actively in the results. More nodes are formed, more branches are created, leaf numbers increase, the plant is growing at its finest.
Some growers opt to use 18/6 as their
photoperiod. This is 18 hours of light, six hours of darkness light regime. Under these conditions the plant will grow quite naturally but not as vigorously as the 24/0
photoperiod.
The 18/6
photoperiod expels 3/4 the amount of light that a 24/0
photoperiod does. Although this does not mean that a plant produces 1/4 less leaves,branches and nodes under the 18/6
photoperiod, it certainly does show the correlation between light and cannabis growth. As we have said already, cannabis is a light demanding plant. There are no problems associated with 24/0 and although some have attributed cannabis sexual dysfunction (the
hermaphroditeconditon) to 18/6
photoperiod these problems are actually the result of heat stress.
A 24/0
photoperiod requires that your grow room temperature be kept well monitored. The 18/6 option is cheaper to run. You use a quarter less electricity and this will have an impact on your electricity bill. Also the 18/6
photoperiod will generally extend the bulb's lifespan. During the 6 hours of darkness the grow room is allowed to cool down for this period but a well maintained good grow room setup should not require a cooling down period.
24/0 and 18/6 both share the same problem though. Once you start the
photoperiod you should keep that way especially when the plants near maturity (the preflowering stage). An irregular
photoperiod can cause more males than females to develop. It can also cause sexual dysfunction to appear. Whether you choose 24/0 or 18/6 as your vegetative
photoperiod try to keep that
photoperiod unitl your plants are mature enough to express their sex."
Greg Green "The Cannabis Grow Bible"
While normally I don't put a whole lot of value in these books - quotes ripped from another forum - it is something the socalled experts agree on.
My plants also mature faster on 24 hrs light then 20/18/12 causing them to flower faster too. Meaning less stretch again. I determine sex based on prerlower after 25-30 days veg. They seem to grow older faster in terms of physiological age at the same chronological age because they can do more in a longer days.
In some advanced greenhouses they measure the plant directly to detect photosynthate saturation (forgot the name, they measure leaves, expensive toy), which has shown that many C3 plants are better off under alternative indoor light schedules for many different reasons, especially structure and length, but those often are tuned to get max yields (or money for the longest roses...). Fortunately indoors the grower together with mother nature determines the light schedule, not mother nature on its own, she can be a real stubborn bitch. That's more for outdoor landrace hippies (which I don't mean offensive... Need those too).
en.wikipedia.org
