Going to seed already !

I love coriander and have grown it from seed last year and this. The problem is although they are young plants in pots they are going to seed already, they turn quite bitter once they start. Does anyone have any advise?, am I doing something wrong. The new leaves are quite feathery.

 

Decided to have a read up on coriander and it seems to like cool conditions,I think I may have kept it in the greenhouse too long. I also discovered you can get a slow bolt type coriander seeds. Well done me ! I must make make more of an effort to make use of my gardening books. :rolleyes: :D