18/6 would be your best lighting 18hrs of light
no you do not need to do anything to make it flower it will do it automatically hence the name
I dont think the OP is asking this question.
I think he is refering to the colour spectrum of the lights?
If so what is your HPS is it just red spectrum or dual spectrum?
I like dual spectrum lamps as they contain both blue and red spectrum ideal for both veg and flowering.
BUt you should be able to grow right the way through using your HPS.
However i would point out that you want something gentle for propagation but the 70w hps maybe ok for this but i dont know as i havent tried using a 70w i have a 600w.
But i use 2 different types of flouros during propagation and early veg stage
24w T5 6400k
200w ECO CFL
Then move to my 600w Dual spec HPS
J