Why 12/12 instead of 11/13, 13/11 or 14/10 for flowering?

Is it because it cuts everything down the middle? Would'nt a little bit more light give it that extra photo period to do what plants do? And on the other hand, would'nt 1 hour less of light let it do the nighttime internal building that it dose? Just why is it 12/12? Who set that? Has anyone ever differ the setting on the flower time?

The 12 hour split comes from wild cannabis needing to flower and produce seed before winter arrives.

During the spring and summer, the days are lengthening and nights shortening so the plants just grow in size and mature under ideal conditions. Then the summer solstice occurs and the nights begin to lengthen and the days shorten. At the autumnal equinox, both night and day length is the same (12/12). At this point, the 12+ hours of darkness allows specific hormones, that are only produced in darkness, to build up to high enough levels to induce flower formation. The timing of this starting at the equinox allows the plants to finish breeding and produce seeds before winter conditions become too severe and they are killed.

In equatorial regions, night and day length doesn't vary as much throughout the year so equatorial strains have to be more sensitive to the lesser variations in night/day length but they have longer to reproduce (winter conditions aren't usually going to kill them). The further away from the equator, plants may have to begin flowering sooner in order to beat severe winter conditions (which will kill them), so they may even begin flowering when night length is more along the lines of 11 hours long and before the autumnal equinox occurs in. The specific difference in when they begin flowering according to night length is inherited genetically and expressed as a part of their 24-hour circadian rhythms.

It doesn't have to be 12/12, it just has to be at least 12 hrs of dark. The reason we use 12/12 is so on off times are the same am and pm. 13 light and 12 dark would work fine if you want to keep track of the on off times.

Illegal Smile said:

It doesn't have to be 12/12, it just has to be at least 12 hrs of dark. The reason we use 12/12 is so on off times are the same am and pm. 13 light and 12 dark would work fine if you want to keep track of the on off times.

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...didi u just say that witha straight face.....
illigal smile(guilty)...i just had to laugh at that avatar

Illegal Smile said:

It doesn't have to be 12/12, it just has to be at least 12 hrs of dark. The reason we use 12/12 is so on off times are the same am and pm. 13 light and 12 dark would work fine if you want to keep track of the on off times.

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13 light/12 dark would probably work since it's close to a 24 hour cycle. But the further outside of a 24 hour cycle you go (don't forget plants operate on circadian rhythms just like animals or even more-so than animals), the more likely you are to mess up hormone production. Because, if day/night cycles don't fit into roughly 24 hours, a photo-period plant like cannabis will free cycle hormone production until/if things get matched back up to it's circadian rhythm.

I have to admit that I'm totally new to this but at least outdoors the 12/12 deal can't be how it works. 12/12 doesn't happen where I'm at until September 25th... That's a little bit after our first avg frost date. From the fellow folks in my state that grow they report outdoor flowering typically begins around the end of July or beginning of August - daylight hours are at about 14 hrs & 45 min. That is down just 1 hr from the equinox daylight hrs of 15 hrs 50 min. Frrom aug 1 daylight hrs start losing light more quickly... By the end of Sept 3&1/2 hrs have been lost. I would guess the beginning of that change triggers flowering outdoors. Again I'm new so I could be off base here. And indoor growing is a whole different ball game.

Creeper38 said:

I have to admit that I'm totally new to this but at least outdoors the 12/12 deal can't be how it works. 12/12 doesn't happen where I'm at until September 25th...

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Read my second paragraph above. Plants that grow in non-equatorial regions have to begin flowering sooner than the autumnal equinox. The further the plants are from the equator, the more time they need to finish reproducing.

Creeper38 said:

That is down just 1 hr from the equinox daylight hrs of 15 hrs 50 min. Frrom aug 1 daylight hrs start losing light more quickly... By the end of Sept 3&1/2 hrs have been lost. I would guess the beginning of that change triggers flowering outdoors. Again I'm new so I could be off base here. And indoor growing is a whole different ball game.

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Cut and paste: Although the word equinox is often understood to mean "equal [day and] night", this is not strictly true. For most locations on earth, there are two distinct identifiable days per year when the length of day and night are closest to being equal; those days are referred to as the "equiluxes" to distinguish them from the equinoxes. Equinoxes are points in time, but equiluxes are days. By convention, equiluxes are the days where sunrise and sunset are closest to being exactly 12 hours apart.

I screwed up... Didnt mean equinox hrs. Meant solstice hrs... We actually have 9 days that are at solstice hrs...or the longest daylight hrs. Per day. Conversely we don't actually have an autumnal equinox...closest we get is on Sept 26 with 11 hrs & 59 min. At that point we're losing 4 min of daylight per day.

Wow the terminologies used. Has anyone ever toyed with their indoor lights to see what hour setting produced the most? Or is everyone going to stick with the 12/12? I thought equinox was a water filter.