Dual spec or Red spec?

Okay so im going to be growing some purple jems auto-flowers and was wondering what spectrum of lighting to use ive heard red spectrum is the best or should i use a dual spectrum, the bulb im going to buy are 300 actual watts btw, also the dual spec has seperate filaments one half 2700k other half 6400k and im planning on doing a photoperiod grow, so which one red or dual?

Bump up...

I would use dual, it's good to have the full spectrum of light.

You can start off with bluish light then switch to red or just use both throughout the grow

yea, generally its blue for veg, red/yellow for flower. but a full spectrum is best, it simulates natural light much better.

thanks guys, im not actually starting a grow untill january but i need all the info i can get

i use a dual spectrum 125watt cfl which i thought would be fine all the way through and it was really great for vegging but not for flowering as the buds just dont get big so ive switched to a 250watt red cfl for flowering and between the both it works really great.

HAHA sorry guys ive decided on a 150w HPS