I find coriander a right sod to grow. The germination time is really long, perhaps as long as four weeks. That said I may I might have found the best way for me. If you gently crack the round seeds into its two halves with a rolling pin or similar (one round seed will actually grow two plants) then soak them in water for a few hours before you plant them out that seems to be the best method. I did try the method I found on Youtube here, but found that although they germinated quickly the seedlings were really spindly.Clint
Do coriander seeds I buy from the Asian shop germinate, if so I've loads.
Anyway if you or anyone else can or has find a good method for growing coriander either in pots or outside then please share