How does light spectrum/intensity change over the 12/12 cycle

The name suggests it all. How does the intensity of the lighting change over the flowering cycle? I'v read about people adding lights after the 3rd week of flowering, but couldn't you of added that light all along to get the plants as much energy as possible?

The other part of the question is how does the light spectrum change over the 12/12 cycle? Or does it at all. Iv read about people adding more warm(2700k) lighting towards the end? Is there a preference to spectrum throughout the 12/12 cycle?

Any valuable info would be great to get this thread helping others as well

Yes, because during the flowering season the angle at which light from the sun hits the Earth is smaller, the spectrum is generally lower (from 5000k to 3000k approx). This is why some growers change their bulbs during flowering to have a warmer spectrum.

I personally believe that you could use a warm spectrum throughout the entire growth, since I've never seen any difference in yield or potency in doing so.

Doctor Cannabis said:

Yes, because during the flowering season the angle at which light from the sun hits the Earth is smaller, the spectrum is generally lower (from 5000k to 3000k approx). This is why some growers change their bulbs during flowering to have a warmer spectrum.

I personally believe that you could use a warm spectrum throughout the entire growth, since I've never seen any difference in yield or potency in doing so.

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Yeah you can grow with HPS or 2700K CFL's all the way through a grow, but you can get more yield from using HID or CFL's for veg and HPS or warmer spectrum CFL's for flower.

Plants veg much better and faster under HID's or cooler spectrum lighting than what they do under HPS.

O ok thanks guys, to clear it up, im only refering to the flowering cycle, and wondering if it'd be better to have stationary light during flowering( i use hps, and cfls) or to have a little more 6500k during the begining of flowering and then after about the 5th week, start to add only warm spectrum.

Personally i think im going to just keep stationary light through out the whole grow and not add additional light at different times throughout flowering. Although i will have both spectrums in my flowering cab. I have a hps an then a 125 t5 fixture and then will be adding 6500k cfls

but i was just seeing if anybody would bring up points to change my mind, but im always still free for dicussion and input, keep it comin(only if you have experience in this, dont just reiterate whats already known)

Good deal fawk, thanks. ill power up everything