But I believe that the rest or dark periods allow the plant to process enough photosynthate in between light periods to be able to process that light.
There is really nothing to argue about. Just to
measure.
d9
Vegetative light schedules
24/0-20/4-18/6, and now 8/4/8/4.
For some time I have been using a vegetative light schedule of 8 hours on, 4 hours off, 8 hours on, and 4 hours off. Or 16 hours of light per day.
My plants are reaching the same size in the same time frame with this schedule as they as they did with the 20/4 schedule I was using immediately prior to the change to 8/4/8/4.
Everyone has seen the numerous threads over the years about which vegetative light schedule is best. They always degenerate into arguments that are never resolved. One person swearing by 24/0 and another saying 18/6 is the best.
The arguments for or against any regime are flawed without considering the amount of light actually received by the plant. And, as we shall see, all the arguments are futile and rendered obsolete simply by using a tool to measure your light.
If you are using powerful lighting at the right distance you need less time to achieve the size plant you desire than someone using weak lighting.
What is the right distance? Dr El Sohly at the University of Mississippi has determined that the maximum rate of photosynthesis for cannabis occurs at 1500 umols of photon bombardment, which is an instantaneous measurement of flow. The only way to determine this is with a quantum sensor. This distance to produce 1500 umols will be different for every type of lighting or bulb.
I can do the 8/4/8/4 routine because I use a 1k hps hortilux during the vegetative period and run my light at 14” to the closest part of the plant, which is the distance producing a 1500 umol flow with my light.
Someone using fluorescents or low wattage mh or hps bulbs in the vegetative stage will have to give the plant more time to reach the same goal. If the lights you use are very weak you may not be able to reach the same growth I get even if you go 8 more hours and give the plant 24/0.
All of this is because of the daily light integral. The total amount of accumulated light a plant gets in a 24 hour or diurnal cycle. The maximum daily light integral for cannabis is not currently known but we know that it is a “high light” plant. We know that the most sunlit places on earth rarely get more than about 60 moles/day and that plants in most greenhouses get no more than about 30 moles/day.
In order to determine the correct vegetative light exposure for your plant with your light you need a quantum meter.
Using one I was able to determine that, at 14”, with my light, I was able to deliver approximately 32 moles in each 8 hour period. Or 64 moles/day. A huge amount of light that , if given in one continuous period, would probably be more than the plant could process.
But I believe that the rest or dark periods allow the plant to process enough photosynthate in between light periods to be able to process that light.
There is really nothing to argue about. Just to
measure.
d9
lol I just asked in another thread if anyone has tried 6/6/6/6 or 7/5/7/5 or somethine alone those lines now I read you do 8/4/8/4 I knew someone must of tried it. have you experimented with other light schedules other then 8/4/8/4? do you find that the best?
Any digital timer with programmable memory can do that.