Would i get fast growth with my light on all the time
DUE TO LACK OF TRUE KNOWLEDGE, THIS MAY SOUND COUNTER INTUITIVE BUT YOU SAVE OVER $50 WITH 1000 WATT LAMPS BY VEGGING LONGER DAYLIGHT HOURS.
First it ALSO depends on many factors, Biotic factors (nute schedule, genetics, nute type, etc) and abiotic factors (pests, temp, wind, hunidity etc. Then you have to know peak levels of all limiting factors, when they occur during the day, during the life cycle etc. This is why it is a good idea to grow the same strain for a while, even if you vary many other strains, at least study one that you master well. I know one of my strains so well, I can toy with the growth, nute regimen etc and actually give the smoker a different high experience each crop with the same strain. Sometimes, it is all I need cause the base of the high is the same, some people like one strain and simply need a slight variance every so often without changing an entire plant type.
That said, know when to orchestrate all your limiting factors to maximize your photosynthetic rate, and nute assimilation for max dry weight and quality bud. There is no strait answer to your question. I can only give you a general guide. It is long but once you get it, you will conclude for yourself based on your factors in your grow environment. The general things will be the same though, like ups in downs in cost.
You may ask why I went in such detail well I am writting a book on Cannabis growing so this is actually something I have done over and over to make sure I nailed it before publishing and looking like a fool. This is 10 harvest, minimum 20 plants a a harvest, almost a year (I have a crop a month). Now, I did take measurements each of the 20 plants for a total of minimum 20 X 10 = 200 plants, though a few months I did 25. I simply made this experiment part of my routine in order to take away stress.
Objective of the experiment was to nail down the difference in cost between 24 hour vegging versus 18 and I used my 12 hour flowering as a control because all crops go through that. I also Measured quality marketable bud size, and quality dry weight because it is worthless gardening without the end product in mind. Less Popcorn, more money, period, and knowing your strains natural water weight and how to keep this in check is very important. Water to plants, is like fat to humans. You want "lean" plants so you have high dry weight.. Large Buds at harvest time does not always translate to large dry weight or quality bud.
So, I went out a purchased a an instrument to measure my KW/h consumption per appliance for $7 at the Home Depot.
I then measured several factors during the Veg periods. Because flowering 12/12 is universal to all my strains, I used the 12/12 time as my control and took relevant measurements there too (Mainly flower growth rate, marketable size bud percentage)
I am still working on interpreting the results as you can see in the images, I have a sleuth of interesting and useful findings. Some flat out awesome but not so relevant to the experiment.
You will see in the tables that
Basically, based on my usage, growth rate and all, I save $53.35 +/- $5 vegging 24 versus 18 hour days but lose about 11 production days each time due to a reduced growth rate at 18 hour days compared to 24 hour days.
This is over 10 harvests and over 200 plants. I intend to take this research to 1000 plants eventually.
I concluded that the hypothesis that Vegging under 18 hour light does not advantage you to anything but wastes time to market and money. Therefore I concluded that this hypothesis STATISTICAL WATERS on its own, hands down. Basically by vegging 18 hours you are really trading about 2 weeks of production time and spending about an 1/8 worth of weed you could make up by selling shake, really, is spending $52.35 a month worth it for me and to pad 2 weeks to reach my target veg height of 28 inches at that? Hell NO!
PS, all plants photosynthesis equally during the dark cycle *the only CO2 fixation going on at night when lights are out. So you have to realize that plants that receive 24 hour darkness, not only eat 25% more because the dark cycle of CO2 Fixation is an evolutionary trait to compensate for the lack of available light for Co2 Fixation during the dark ,and therefore, plants under 24 hour lighting not only feed 25% extra, the grow at a rate to the power slightly to the 3rd times faster over time because if I had to really be more technical, since growth rate is exponential to feeding rate^3.
To save time I posted a screen shot from Wikipedia: for all you math lovers. Look at the numbers, vegging less time costs you more money