Photo period?

[Gadhooka]

I noticed that there is about a 1/2 an hour on either side of sunrise and sunset of "twilight".

Does the light period begin at twilight or Sunrise/Sunset?

 

[jash]

i think you count the sunrise/sunset time

 

[Mutt]

Actually to judge photo period is very difficult outdoors. Indoors its either on or off. Outdoors its much more gradual, plus each day does not have the same "exact to the minute" length as the day before.
When the days get shorter is when it tells the plant to commence flower. The gradual change is what makes the Outdoor plants bigger and heavier than indoors when we only veg 4-6 weeks. Outdoors it vegges for months.

 

[Hick]

I noticed that there is about a 1/2 an hour on either side of sunrise and sunset of "twilight".

Does the light period begin at twilight or Sunrise/Sunset?

..the "photo period" would end when the light is no longer strong enough to allow the plant to "photosynthesise"...IMHO
"twilight"..would that be "civil, nautical or astronomical"..twilight?..
[FONT=Arial, Helvetica]Twi A: 5:46am
Twi N: 6:16am
Twi: 6:44am
Sunrise: 7:09am
Sunset: 7:51pm
Twi: 8:16pm
Twi N: 8:44pm
Twi A: 9:14pm
there is nearlly an hour difference in "civil" and "astronomical"..."I" personally don't know exactly 'when' plants call twilight...
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