Allotments 4 All

I need some help I have 50 Japanese onion sets I would like to plant them in pots 35cm high 43cm diameter, can anyone tell me how deep to plant , how many I might get in a pot , and when to plant, when to water, what to feed, I'm a complete novice and never tried anything like this

my mind boggles 50 would take up quite a bit of ground at six inches apart mine grew quite big last year. sorry not being very helpfull I am sure somebody has done this and will be able to advise you they are a versatile lot
marg

thanks marg i get the 6inches apart what about depth ?