Space

i am attempting my 1st ever grow and am very VERY limited for space so i am only trying to grow 1 or maybe 2 small plants i have already chosen to use a large cardboard box all kitted out ( i know its not the safest but its either that or i cant grow) what i need to know is a 2ft high by 1ft wide and deep box with a 125w cfl lamp big enough to grow a small plant in and what is the smallest you can grow a plant before flowering?

any help and advice would be great thanks

look up PC box grows
This link helps alot good for i ideas luck dude
http://www.youtube.com/watch?v=FmyrhaC6sEc&feature=fvw