growing cycles!!

[psymushroom]

hello people maybe this is a big stupid question..but im beginner in growing weed indoors!!and its so strange all this stuff about growing, flowering and litghts!!!
i learn that to grow a plant i need hps lamp...but after that, i found that i need 2 kinds of lamps to grow a plant..??
1 metal halide lamp that produce blue/white color for growing period and
1 hps lamp that produce red/yelow color for the flowering period.....
is that the right deal to having good plant?
and how do i know when growing period stops and comes the flowering period to change the lamp?
i meen for example..that there is plants to grow in 5 weeks and plants to grow in 10 weeks..
also so many different seeds from plant kinds..how do i know how long is the growing period & flowering period for any of them??? :?

also about lighting...i must have the ligths on 24 hours for all the time? or 18 hours per day for all the time?
and if i use the 18hours growing cycle,in flowring period i must have to change the cycle of lighting??
heeeeeeeeeeeeeeeelpppp!!!

 

[Illegalsmile]

http://video.google.com/videoplay?docid=-6985232172273655970#

 

[psymushroom]

allright!! thanks bro
so...as i understand i decide when i take them from growing light and put the flowering light? i can stop the plant in a desired height in growing,ubout 50cm and then flower it??its for all the plants the same?